TY - JOUR A1 - Schulz, Burkhard A1 - Stiller, Burkhard A1 - Zetzsche, Thomas A1 - Knochenhauer, Gerald A1 - Dietel, Reinhard A1 - Brehmer, Ludwig T1 - Crystal structure of 2,5-Di(4- methoxycarbonyl-phenyl)-1,3,4-oxadiazole characterized by AFM and IR- spectroscopy Y1 - 1994 ER - TY - JOUR A1 - Mercer, Frank W. A1 - McKenzie, M. A1 - Bruma, Maria A1 - Schulz, Burkhard T1 - Synthesis and properties of fluorinated polyimides and fluorinated poly(imide-amide)s containing pendent cyano groups Y1 - 1994 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Knochenhauer, Gerald A1 - Brehmer, Ludwig A1 - Janietz, Silvia T1 - Stuctures and properties of aromatic poly(1,3,4-oxadiazole)s Y1 - 1994 ER - TY - JOUR A1 - Bruma, Maria A1 - Mercer, Frank W. A1 - Schulz, Burkhard A1 - Dietel, Reinhard A1 - Fitch, J. A1 - Cassidy, Peter T1 - Study of crosslinking process in fluorinated poly(imide-amide)s containing pendant cyano groups Y1 - 1994 ER - TY - JOUR A1 - Bruma, Maria A1 - Mercer, Frank W. A1 - Schulz, Burkhard A1 - Dietel, Reinhard A1 - Fitch, J. A1 - Cassidy, Peter T1 - Study of crosslinking process in fluorinated poly(imide-amide)s containing pendant cyano groups Y1 - 1994 ER - TY - JOUR A1 - Bruma, Maria A1 - Mercer, Frank W. A1 - Schulz, Burkhard A1 - Dietel, Reinhard A1 - Neumann, Werner T1 - Fluorinated poly(benzoxazole-imide)s Y1 - 1994 ER - TY - JOUR A1 - Bruma, Maria A1 - Schulz, Burkhard A1 - Mercer, Frank W. T1 - Synthesis and characterization of fluorinated poly(imide-pyridazine- amide)s Y1 - 1994 ER - TY - JOUR A1 - Janietz, Silvia A1 - Schulz, Burkhard T1 - Electrochemical studies on thin films of poly(arylene-1,3,4-oxadiazole)s Y1 - 1994 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Janietz, Silvia T1 - Electrochemical studies on thin films of poly(arylene 1,3,4-oxadiazole)s Y1 - 1994 ER - TY - JOUR A1 - Schulz, Burkhard T1 - Eine neue Synthesevariante für aromatische Poly(1,3,4-oxadiazole) Y1 - 1994 ER - TY - JOUR A1 - Schulz, Burkhard T1 - Neue thermostabile Polyheterocyclen Y1 - 1994 ER - TY - JOUR A1 - Schulz, Burkhard T1 - New aspects of the solid-state structures and electrochemical properties of aromatic Poly(1,3,4- Oxadiazole)s Y1 - 1994 ER - TY - JOUR A1 - Schulz, Burkhard T1 - Struktur und Eigenschaften dünner Schichten aus aromatischen Poly(1,3,4- oxadiazol)en Y1 - 1994 ER - TY - JOUR A1 - Reiche, Jürgen A1 - Freydank, A. A1 - Dietzel, Birgit A1 - Katholy, Stefan A1 - Knochenhauer, Gerald A1 - Zetzsche, Thomas A1 - Schulz, Burkhard A1 - Brehmer, Ludwig T1 - Komplexe Strukturanalytik von Oxadiazol-Mono- und Multischichten Y1 - 1995 ER - TY - JOUR A1 - Brehmer, Ludwig A1 - Dietzel, Birgit A1 - Freydank, Anke-Christine A1 - Katholy, Stefan A1 - Knochenhauer, Gerald A1 - Reiche, Jürgen A1 - Schulz, Burkhard A1 - Zetzsche, Thomas T1 - Langmuir- und Langmuir-Blodgett-Filme amphiphiler Oxadiazole Y1 - 1995 ER - TY - JOUR A1 - Okatova, Olga V. A1 - Lavrenko, Peter N. A1 - Fedotov, Y. A. A1 - Schulz, Burkhard T1 - Polyelectrolyte behavior of some new polyheteroarylene derivatives in sulfuric acid Y1 - 1995 ER - TY - JOUR A1 - Sava, Ion A1 - Schulz, Burkhard A1 - Zhu, Shigen A1 - Bruma, Maria T1 - Synthesis and characterization of new silicon-containing poly(arylene-1,3,4-oxadiazole)s Y1 - 1995 UR - http://hip.sagepub.com/ U6 - https://doi.org/10.1088/0954-0083/7/4/011 SN - 0954-0083 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Brehmer, Ludwig A1 - Dietzel, Birgit A1 - Zetzsche, Thomas T1 - Preparation and characterization of ordered thin films based on aromatic poly(1,3,4-oxadiazole)s Y1 - 1995 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Knochenhauer, Gerald A1 - Brehmer, Ludwig A1 - Janietz, Silvia T1 - Stuctures and properties of aromatic poly(1,3,4-oxadiazole)s Y1 - 1995 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Stiller, Burkhard A1 - Zetzsche, Thomas A1 - Knochenhauer, Gerald A1 - Dietel, Reinhard A1 - Brehmer, Ludwig T1 - Characterization of 2,5-di(p-tolyl-1,3,4- oxadiazole) crystals by IR-spectroscopy and atomic force microscopy Y1 - 1995 ER - TY - JOUR A1 - Bauer, J. A1 - Schulz, Burkhard A1 - Brehmer, Ludwig A1 - Bötcher, M. A1 - Jagdhold, U. A1 - Höppner, K. A1 - Kulesch, A. A1 - Dietzel, Birgit T1 - Anwendung von Langmuir-Blodgett-Schichten als Resist für die Niederspannungs-Elektronenstrahl-Lithografie Y1 - 1995 ER - TY - JOUR A1 - Bruma, Maria A1 - Schulz, Burkhard A1 - Mercer, Frank W. T1 - Polyamide copolymers containing hexafluoroisopropylidene groups Y1 - 1995 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Brehmer, Ludwig T1 - Preparation and characterization of ordered thin films based on aromatic poly(1,3,4-oxadiazole)s Y1 - 1995 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Janietz, Silvia T1 - Preparation and characterization of thin films containing aromatic poly(1,3,4- oxadiazole)s Y1 - 1995 ER - TY - JOUR A1 - Schulz, Burkhard T1 - Structure and properties of thin polyoxadiazole films Y1 - 1995 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Brehmer, Ludwig A1 - Knochenhauer, Gerald T1 - Supramolecular structures of aromatic 1,3,4-oxadiazole solids Y1 - 1995 ER - TY - JOUR A1 - Janietz, Silvia A1 - Schulz, Burkhard T1 - Elektrochemische Untersuchungen an aromatischen Poly(1,3,4-oxadiazol)en Y1 - 1995 ER - TY - JOUR A1 - Lavrenko, Peter N. A1 - Strelina, Irina A. A1 - Okatova, Olga V. A1 - Schulz, Burkhard T1 - Orientation of naphthylene ring in the new poly(naphthylen-1,3,4-oxadiazole)s molecules Y1 - 1996 ER - TY - JOUR A1 - Bruma, Maria A1 - Hamciuc, Corneliu A1 - Hamciuc, Elena A1 - Mercer, Frank W. A1 - Belomoina, Nataliya A1 - Schulz, Burkhard T1 - Heterocyclic polyamides containing hexafluoroisopropylidene groups Y1 - 1996 ER - TY - JOUR A1 - Bruma, Maria A1 - Hamciuc, Corneliu A1 - Sava, Ion A1 - Hamciuc, Elena A1 - Mercer, Frank W. A1 - Fritzsche, P. A1 - Schulz, Burkhard T1 - High temperature polyamides containing pendant imide groups Y1 - 1996 ER - TY - JOUR A1 - Zhu, Shigen A1 - Schulz, Burkhard A1 - Bruma, Maria A1 - Brehmer, Ludwig T1 - Comparative study of the thermal properties of related aromatic polyhydrazides and poly(1,3,4-oxadiazole)s Y1 - 1996 UR - http://www3.interscience.wiley.com/journal/5401/home?CRETRY=1&SRETRY=0 U6 - https://doi.org/10.1002/(SICI)1099-1581(199612)7:12<879::AID-PAT600>3.0.CO;2-X SN - 1042-7147 ER - TY - JOUR A1 - Hamciuc, Corneliu A1 - Schulz, Burkhard A1 - Bruma, Maria T1 - New polyhydrazides and polyoxadiazoles containing pendent phenoxy groups Y1 - 1996 ER - TY - JOUR A1 - Janietz, Silvia A1 - Schulz, Burkhard T1 - Electrochemical investigation on poly(arylene-1,3,4-oxadiazole)s Y1 - 1996 ER - TY - JOUR A1 - Okatova, Olga V. A1 - Andreeva, Katharina A. A1 - Schulz, Burkhard T1 - Thermal hydrolytic degradation of polyoxadiazole derivatives Y1 - 1996 ER - TY - JOUR A1 - Schulz, Burkhard T1 - Herstellung und Charakterisierung geordneter ultradünner Poly(arylen- 1,3,4-oxadiazol) Schichten Y1 - 1996 ER - TY - JOUR A1 - Hamciuc, Elena A1 - Hamciuc, Corneliu A1 - Bruma, Maria A1 - Stoleriu, Andre A1 - Schulz, Burkhard T1 - Poly(hydrazide-ester)s and poly(1,3,4-oxadiazole-ester)s containing pendent phenoxy groups N2 - A series of new arornatic poly(hydrazide-ester)s has been synthesized by solution polycondensation of two diacid dichlorides containing preformed ester groups with phenoxyterephthaloyl dihydrazide or with a mixture of phenoxyterephthaloyl dihydrazide with terephthaloyl- or isophthaloyl dihydrazide in N-methyl-2-pyrrolidinone. The thermal cyclization of the poly(hydrazide-ester)s gave the corresponding poly(1,3,4-oxadiazole-ester)s containing pendent phenoxy groups. The polymers were characterized by viscometry, solubility measurements, IR spectroscopy, differential scanning calorimetry and thermogravimetric analysis. Y1 - 1997 ER - TY - JOUR A1 - Orgzall, Ingo A1 - Lorenz, Bernd A1 - Mikat, Jürgen E. R. A1 - Dietel, Reinhard A1 - Knochenhauer, Gerald A1 - Schulz, Burkhard T1 - Raman and IR spectroscopic investigation of aromatic 1,3,4-oxadiazole polymers and oligomers N2 - The molecular structure of poly(p-phenylene-1,3,4-oxadiazole) (POD) is investigated using i.r. and Raman spectroscopy. Both methods reveal characteristic differences for the a- and b-POD forms that are most obvious in the spectral region between 1500 and 1650 cm-1. The spectra for dimer and tetramer compounds already show the same features as found for longer chains. Based on molecular modelling calculations these differences are assigned to cis and trans conformations of the main chain segments. High pressure measurements show a linear shift of the Raman lines and support the result of the thermodynamic stability of the trans conformation. Y1 - 1997 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Stiller, Burkhard A1 - Zetzsche, Thomas A1 - Knochenhauer, Gerald A1 - Brehmer, Ludwig T1 - Characterization of crystals based on 1,3,4-oxadiazoles by atomic force microscopy N2 - The surface structures of crystals based on aromatic oxadiazoles were investigated by AFM. The crystal structure for 2,5-di(p-tolyl)-1,3,4-oxadiazole (DTO) differs from that of 2,5-di (4-methoxycarbonyl-phenyl)-1,3,4- oxadiazole (DMPO). In DMPO all molecules show parallel orientation to the surface in such a way that the surface is formed as well as by the nitrogen atoms of the heterocyclic rings and the methyl groups of the ester substituents. By contrast, the oxadiazole molecules in DTO crystals are oriented perpendicular to the crystal surface. The experimental data are interpreted by molecular modelling. It is shown that there is a difference between molecular structure of the surface, as detected by AFM, and the bulk structure determined by X-ray diffraction. Y1 - 1997 ER - TY - JOUR A1 - Reiche, Jürgen A1 - Zetzsche, Thomas A1 - Helms, Andreas A1 - Freydank, Anke-Christine A1 - Knochenhauer, Gerald A1 - Schulz, Burkhard A1 - Brehmer, Ludwig T1 - Organized molecular films of oxadiazole compounds formed by vacuum deposition Y1 - 1997 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Bruma, Maria A1 - Brehmer, Ludwig T1 - Aromatic poly(1,3,4-oxadiazole)s as advanced materials N2 - Poly(1,3,4-oxadiazole)s have been the focus of considerable interest with regard to the- production of high- performance materials, particularly owing to their high thermal stability in oxidative atmosphere and specific properties determined by the structure of 1,3,4-oxadiazole ring, which, from the spectral and electronic points of view, is similar to a p-phenylene structure.[1] Besides their excellent resistance to high temperature, polyoxadiazoles have many desirable characteristics, such as good hydrolytic stability, high glass transition temperatures, low dielectric constants, and tough mechanical properties. Some polyoxadiazoles have semiconductive properties, other structures can be electrochemically doped and thus made conductive, and other have liquid-crystalline properties, which make them very attractive for a wide range of high-performance applications. They exhibit excellent fiber- and film-forming capabilities, thus being considered for use as heat-resistant reinforcing fibers for advanced composite materials, highly resistant fabrics for the filtration of hot gases, special membranes for gas separation or reverse osmosis, precursors for highly oriented graphite fibers, films, and blocks to be used in the construction of electronic instruments based on X-rays, neutron beams, or a-particles, or in the construction of nuclear reactor walls. Since they were first reported in 1961,[2] a wide variety of polymers containing 1,3,4-oxadiazole rings have been synthesized, and their preparation, characterization, and physico-mechanical properties have been periodically reviewed .[3-8] This article will present a general overview of this class of polymers and will refer to the work carried out by different researchers in the last ten years with the emphasis on the potential uses of such polymers as advanced materials. Y1 - 1997 ER - TY - JOUR A1 - Sava, Ion A1 - Szesztay, Marta A1 - Bruma, Maria A1 - Mercer, Frank W. A1 - Schulz, Burkhard T1 - Compared properties of aromatic polyamides containing silicon in the chain N2 - Two series of aromatic polyamides incorporating silicon together with phenylquinoxaline or with hexafluoroisopropylidene groups have been synthesized and their properties have been characterized and compared with those of related polymers. These polymers are easily soluble in polar amidic solvents such as N-rnethyl-2-pyrrolidinone and dimethylformamide, and in tetrahydrofuran, and can be cast into thin, transparent films from solution. The polyamides have weight- and number-average molecular weights in the range of 10000-40000 and 3000-6000, respectively, and polydispersities in the range of 3-10. They show glass transition temperatures in the range of 236 °C-275 °C and decomposition temperatures above 400 °C. The polymer films have low dielectric constants in the range of 3.26-3.68, and good mechanical properties (tensile strength 74-100 MPa, tensile modulus 180-386 MPa), thus being comparable with other high performance dielectrics. Y1 - 1997 ER - TY - JOUR A1 - Lavrenko, Peter N. A1 - Schulz, Burkhard A1 - Strelina, Irina A. A1 - Okatova, Olga V. T1 - Synthesis and molecular properties of new poly(naphthalene-1,3,4-oxadiazole)s N2 - Poly[(1,4-naphthalene)-2,5-diyl-1,3,4-oxadiazole] and poly[(2,6-naphthalene)-2,5-diyl-1,3,4-oxadiazole] have been synthesized and investigated in conc. H2S04, by the flow birefringence method in comparison with poly(1,4- phenylene)-2,5-diyl-1,3,4-oxadiazole]. Changes in conformation parameters and optical anisotropy of a chain unit induced by incorporation of the naphthalene groups into the macromolecule backbone have been evaluated. Y1 - 1997 ER - TY - JOUR A1 - Bruma, Maria A1 - Hamciuc, Corneliu A1 - Hamciuc, Elena A1 - Mercer, Frank W. A1 - Belomoina, Nataliya A1 - Schulz, Burkhard T1 - Heterocyclic polyamides containing hexafluoroisopropylidene groups N2 - New heterocyclic polyamides have been synthesized by solution polycondensation of aromatic diamines containing phenyl- quinoxaline units with diacid chlorides having both imide and hexafluoroisopropylidene (6F) groups. These polymers are soluble in polar aprotic solvents, such as N-methylpyrrolidone (NMP) or N,N-dimethylformamide (DMF), and can be cast into flexible thin films from solutions. They show high thermooxidative stability with decomposition temperatures above 400°C and glass transition temperatures in the range of 225 - 300°C. The polymer films exhibit good chemical resistance towards deluted acids and good electrical insulating properties with dielectric constants in the range of 3.2 - 3.7. Y1 - 1997 ER - TY - JOUR A1 - Lavrenko, Peter N. A1 - Strelina, Irina A. A1 - Schulz, Burkhard T1 - Dynamo-optical properties of poly(naphthylene oxadiazole)s in sulfuric acid N2 - Flow birefringence induced in dilute solutions of poly[(1,4-naphthylene)-2,5-diyl-1,3,4-oxadiazole] and poly[2,6-naphthylene)-2,5-diyl-1,3,4-oxadiazole] in conc. sulphuric acid has been investigated. The shear optical coefficient was found for these polymers to be approximately double the value of that obtained in the same solvent for poly[(para-phenylene) -2,5-diyl-1,3,4-oxadiazole]. Rigid-chain behaviour of the polymers was characterized by hydrodynamic and dynamo-optical parameters evaluated with application of the worm-like chain model and the "method of similar structures". Change in optical anisotropy of a chain unit induced by incorporation of naphthylene groups into the main chain has been evaluated. Y1 - 1997 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Kaminorz, Yvette A1 - Brehmer, Ludwig T1 - New aromatic poly(1,3,4-oxadiazole)s for light emitting diodes N2 - New aromatic poly(1,3,4-oxadiazole)s were synthesized having excellent film forming properties due to their solubility in common organic solvents. The investigated new polyoxadiazoles can be used as emission material in single layer LED. The poly- oxadiazoles show an emission in the range of blue to yellow light. The external quantum efficiency as well as the turn-on voltage of the devices are influenced when blends of the polyoxadiazole with hole transport materials are used. Y1 - 1997 ER - TY - JOUR A1 - Sava, Ion A1 - Bruma, Maria A1 - Schulz, Burkhard A1 - Mercer, Frank W. A1 - Belomoina, Nataliya T1 - Synthesis and Properties of Silicon-containing Polyamides N2 - A series of aromatic polyamides incorporating silicon together with phenylquinoxaline or with hexafluoroisopropylidene groups has been synthesized by solution polycondensation of a silicon-containing diacid chloride with aromatic diamines having phenylquinoxaline rings or hexafluoroisopropylidene groups. These polymers are easily soluble in polar aprotic solvents, such as N-methylpyrrolidinone and dimethylformamide, and in tetrahydrofurane, and can be solution-cast into thin, transparent films having low dielectric constant, in the range of 3.26 to 3.68. These polymers show high thermal stability with decomposition temperature being above 400 °C and glass transition temperature in the range of 236 °C to 275 °C. Y1 - 1997 ER - TY - THES A1 - Schulz, Burkhard T1 - Entwicklung aromatischer Poly(1,3,4-oxadiazo)e zu Funktionsmaterialien : Beiträge durch chemische Modifizierung und supramolekulare Strukturierung Y1 - 1997 CY - Potsdam ER - TY - JOUR A1 - Reiche, Jürgen A1 - Schulz, Burkhard A1 - Knochenhauer, Gerald A1 - Dietzel, Birgit A1 - Freydank, Anke-Christine A1 - Zetzsche, Thomas A1 - Brehmer, Ludwig T1 - Supramolecular structures formed from heterocyclic aromatic molecules N2 - This paper describes the formation and structure investigation of Langmuir monolayers and Langmuir-Blodgett multilayers formed from amphiphilic derivatives of 2,5-diphenyl-1,3,4-oxadiazole. The 2,5-diphenyl-1,3,4-oxadiazole group as a functional unit with interesting physical and chemical properties is maintained, while the head group, the length of the alkyl chain and the structure of the coupling unit between aromatic and aliphatic part of these linear short-chain amphiphiles is systematically varied in order to explore the influence of this change on the film forming properties and the stability of Langmuir and Langmuir-Blodgett films. Molecular mechanics simulations are shown by these systematic variations to be suitable for the prediction of optimal chemical structures allowing for a stable stratified molecular packing. The combination of a detailed structure investigation of the multilayers based on scanning force microscopy and X-ray data with molecular mechanics simulations yields an insight into the packing of the molecules and the intermolecular interactions. Y1 - 1997 ER - TY - JOUR A1 - Freydank, Anke-Christine A1 - Janietz, Silvia A1 - Schulz, Burkhard T1 - Synthesis and electrochemical behaviour of Amphiphilic 1,3,4-Oxadiazole derivatives Y1 - 1998 ER - TY - JOUR A1 - Freydank, Anke-Christine A1 - Janietz, Silvia A1 - Schulz, Burkhard T1 - Synthesis and electrochemical characterization of new amphiphilic 1,3,4-oxadiazoles N2 - The electrochemical behaviour of new amphiphilic 1,3,4-oxadiazoles were studied by cyclic voltammetry. The influence of the supra- molecular structure on the redox behaviour in liquid or solid solutions, in Langmuir-Blodgett multilayers, and in amorphous films is investigated in detail. The reversible reduction of amphiphilic 2,5-diarylene- 1,3,4-oxadiazoles is significantly influenced by substituents in the para position of the phenylene ring. In the solid states the reduction peak potentials are shifted to more negative values compared to data measured in solution. This shift increases as the film thickness is increased. An influence of the supramolecular order in the solid films was not found. In-situ UV-vis spectroelectrochemistry of LB-multilayers deposited onto indium tin oxide (ITO) glass give evidence for the formation of radical anions in the highly ordered layer. Y1 - 1998 ER - TY - JOUR A1 - Lavrenko, Peter N. A1 - Okatova, Olga V. A1 - Schulz, Burkhard T1 - Stability and degradation of poly(p-pheneylene-1,3,4-oxadiazole) molecules in sulphuric acid N2 - The translational diffusion coefficient and intrinsic viscosity of poly(1,4-phenylene-1,3,4-oxadiazole) molecules in 96% H2S04 have been determined at different stages of degradation of the molecules in acid solution at temperature ranging from 82 to 105 °C. The degradation rate constant, k, has been obtained from the change in the molecular weight, M, of the product degraded in solution with time at high temperature. The activation energy of the hydrolysis process was 103 ± 7 kJmol-1, which is smaller than that of aromatic polyamides in the same solvent. According to our hydrodynamic data, the degree of coiling of the molecules of degraded products does not differ from that of undegraded samples, and our conclusion was that the degradation is not accompanied with a noticeable change in the short- range interactions in the molecular chain and may be understood as a random chain scission. Y1 - 1998 ER - TY - JOUR A1 - Lavrenko, Peter N. A1 - Okatova, Olga V. A1 - Schulz, Burkhard T1 - Hydrodynamic properties and conformation of the molecules of meta- and para-isomers of polyphenyleneoxadiazole in sulphuric acid N2 - Translational diffusion of poly(1,4-phenylene-1,3,4-oxadiazole) in 96% H2S04 was studied, and the intrinsic viscosity of the polymer solution was measured in various stages of degradation at temperatures from 82 to 105°C. The rate constant of the degradation process was determined from variation of the molecular mass of the degradation products with time at a fixed solution temperature, and the activation energy of the process was calculated using the temperature dependence of the rate constant. The activation energy (E = 103 ± 7 kJ/mol) is lower than that for the hydrolysis of aromatic polyamides in sulfuric acid. According to the hydrodynamic data, the degree of coiling of the degradation products is the saine as that of the intact (non-degraded) macromolecules. This indicates that elements of the chernical structure responsible for the short-range order in the macromolecular chain are retained in the course of degradation. Y1 - 1998 ER - TY - JOUR A1 - Bruma, Maria A1 - Sava, Ion A1 - Mercer, Frank W. A1 - Reddy, Victor N. A1 - Köpnick, Thomas A1 - Stiller, Burkhard A1 - Schulz, Burkhard T1 - Silicon-containing poly(amide-ether)s N2 - New aromatic poly(amide-ether)s (II) have been synthesized by solution polycondensation of various aromatic diamines having two ether bridges (I) with a diacid chloride containing silicon, namely bis(chlorocarbonylphenyl)- diphenyIsilane. These polymers are easy soluble in polar amidic solvents such as N-methylpyrrolidinone or dimethylformamide and can be cast into thin flexible films or coatings from such solutions. They show high thermal stability with initial decomposition temperature being above 400 °C. Their glass transition temperatures lie in the range of 220-250 °C, except for polymer He which did not show a clear Tg when heated in a differential scanning calorimetry experiment up to 300 °C. The large interval between the glass transition and decomposition temperatures of pnlymers Ia-Id could be advantageous for their processing via compression molding. The polymer coatings deposited by the spincoating, technique onto silicon wafers showed a very smooth, pinhole-free surface in atomic force microscopy investigations. The free-standing films of 20-30 mm thickness show low dielectric constant, in the range of 3.65-3.78, which is promising for future application as high performance dielectrics. Y1 - 1998 ER - TY - JOUR A1 - Bruma, Maria A1 - Schulz, Burkhard A1 - Köpnick, Thomas A1 - Dietel, Reinhard A1 - Stiller, Burkhard A1 - Mercer, Frank W. T1 - Investigation of thin films made from silicon-containing poly(phenylquinoxaline-amide)s N2 - Thin films in the range of 50 nm to 10 mm thickness have been prepared from NMP solutions of silicon-containing polyphenylquinoxaline-amides which had been synthesized by the polycondensation reaction of aromatic diaminophenylquinoxalines with bis(p-chlorocarbonylphenyl)diphenylsilane. A spin-coating technique onto glass plates or onto silicon wafers was used to make the film, followed by gradual heating to remove the solvent. The resulting films were very smooth and free of pinholes when studied by atomic force microscopy (AFM). They showed a strong adhesion to silicon wafers, were thermally stable in air to above 400 °C and their dielectric constant was in the range of 3.5-3.7. Thermal treatment of the films was performed in order to induce crosslinking. Such treated films became completely insoluble in organic solvents, maintained their smoothness and strong adhesion to the silicon substrate, and did not show any Tg, in DSC experiments. Their FTIR spectra in reflection mode did not show any changes compared with the untreated films, meaning on the one hand that the polymers maintain their structural integrity at high temperature and on the other hand that the number of crosslinks was very low and could not be detected by IR spectroscopy. Y1 - 1998 ER - TY - JOUR A1 - Lavrenko, Peter N. A1 - Okatova, Olga V. A1 - Cherkasov, Victor A. A1 - Schulz, Burkhard T1 - Hydrodynamic properties of Poly(p-phenylene-oxadiazole) in various stages of hydrolytic thermal degradation in sulfuric acid Y1 - 1998 ER - TY - JOUR A1 - Orgzall, Ingo A1 - Lorenz, Bernd A1 - Mikat, Jürgen E. R. A1 - Reck, Günter A1 - Knochenhauer, Gerald A1 - Schulz, Burkhard T1 - Phase transition in 1,3,4-oxadiazole crystals under high pressure Y1 - 1998 ER - TY - JOUR A1 - Bruma, Maria A1 - Schulz, Burkhard A1 - Köpnick, Thomas A1 - Stiller, Burkhard A1 - Hamciuc, Elena A1 - Mercer, Frank W. A1 - Cassidy, Peter T1 - Aromatic polyamides with hexafluoroisopropylidene groups and study of the thin Y1 - 1998 ER - TY - JOUR A1 - Giebler, Rainer A1 - Schulz, Burkhard A1 - Reiche, Jürgen A1 - Brehmer, Ludwig A1 - Wühn, Mario A1 - Wöll, Christoph A1 - Smith, Andrew Phillip A1 - Urquhart, Steven G. A1 - Ade, Harald W. A1 - Unger, Wolfgang E. S. T1 - Near-edge x-ray absorption fine structure spectroscopy on ordered films of an amphiphilic derivate of 2,5- Diphenyl-1,3,4-oxadiazole N2 - The surfaces of ordered films formed from an amphiphilic derivative of 2,5-diphenyl-1,3,4-oxadiazole by the Langmuir-Blodgett (LB) technique and organic molecular beam deposition (OMBD) were investigated by the use of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. For the assignment of the spectral features of the C, N, and O K- edge absorption spectra, fingerprint spectra of poly(p-phenylene terephthalamide)(Kevlar), poly(ethylene terephthalate), poly(p-phenylene-1,3,4-oxadiazole), and 2,5-di- (pentadecyl)-1,3,4-oxadiazole, which contain related chemical moieties, were recorded. Ab initio molecular orbital calculations, performed with explicit treatment of the core hole, are used to support the spectral interpretations. Angle-resolved NEXAFS spectroscopy at the C, N, and O K-edges suggests a preferentially upright orientation of the oxadiazole derivative in the outermost layer of the films. X-ray specular reflectivity data and molecular modeling results suggest a similar interpretation. Y1 - 1999 ER - TY - JOUR A1 - Bruma, Maria A1 - Schulz, Burkhard A1 - Köpnick, Thomas A1 - Stiller, Burkhard A1 - Belomoina, Nataliya A1 - Mercer, Frank W. T1 - Synthesis and study of aromatic polyamides containing silicon and phenylquinoxaline rings in the main chain N2 - New poly(phenylquinoxaline-amide)s with silicon in the main chain have been prepared by polycondensation reaction of a diacid chloride, namely bis(p-chlorocarbonyl-phenyl)-diphenylsilane, with aromatic diamines containing one or two phenylquinoxaline rings separated by a flexible bridge such as ether or methylene. These polymers were easily soluble in polar aprotic solvents such as N-methylpyrrolidinone (NMP) and dimethylformamide (DMF) and showed high thermal stability with decomposition temperature being above 450°C and glass transition temperature in the range of 260- 304°C. Polymer solutions in NMP were processed into thin flexible films which exhibited very smooth surfaces, free of pinholes when studied by atomic force microscopy. The free-standing films showed a dielectric constant in the range of 3.6-3.7. Y1 - 1999 ER - TY - JOUR A1 - Bruma, Maria A1 - Hamciuc, Elena A1 - Schulz, Burkhard A1 - Köpnick, Thomas A1 - Stiller, Burkhard A1 - Mercer, Frank W. T1 - Synthesis of fluorinated poly(phenylquinoxaline-amide)s and study of thin films made therefrom N2 - A series of five fluorinated poly(phenylquinoxaline-amide)s were synthesized by a polycondensation reaction of a diacid chloride containing the hexafluoroisopropylidene (6F) group, namely 2,2-bis(p-chlorocarbonylphenyl)- hexafluoropropane, with various aromatic diamines incorporating two phenyl-substituted quinoxaline rings. These polymers were easily soluble in polar aprotic solvents such as N-methylpyrrolione (NMP), dimethylformamide (DMF), and tetrahydrofurane (THF), and showed a high thermal stability with decomposition temperatures above 400 °C and glass transition temperatures in the range of 260-290 Tg. Polymer solutions in NMP were processed into free-standing films that showed low dielectric constant values, in the range of 3.4-3.9, and good mechanical properties, with tensile strength in the range of 40-80 MPa and elongation to break in the range of 22-55%. Very thin films, in the range of tens of nanometer, which were deposited onto silicon wafers exhibited very smooth surfaces, free of pinholes when studied by atomic force microscopy (AFM). Y1 - 1999 ER - TY - JOUR A1 - Bruma, Maria A1 - Schulz, Burkhard A1 - Köpnick, Thomas A1 - Stiller, Burkhard A1 - Mercer, Frank W. T1 - Study of thin films made from aromatic polyamides with silicon and phenylquinoxaline rings in the main chain N2 - Aromatic polyamides containing silicon and phenylquinoxaline rings in the main chain have been prepared by polycondensation reaction of a silicon-containing diacid chloride, namely bis(p-chlorocarbonylphenyl) -diphenylsilane, with various aromatic diamines having preformed phenylquinoxaline units. These polymers were easily soluble in polar aprotic solvents, such as N-methylpyrrolidinone (NMP) and dimethylformamide (DMF), and in tetrahydrofurane. They showed high thermal stability with decomposition temperature being above 450°C and glass transition temperature in the range of 253-304°C. Polymer solutions in NMP were processed into thin films having the thickness of tens of nanometer to 10 mm, by spin-coating onto glass plates or silicon wafers. The films had strong adhesion to substrates and exhibited very smooth surfaces, free of pinholes, in atomic force microscopy (AFM) studies. The free-standing films had dielectric constant in the range of 3.48-3.69. Thermal treatment of the films up to 350°C rendered them completely insoluble in organic solvents, while maintaining their smoothness and strong adhesion to the silicon substrate, and with no Tg in DSC experiments. Their FTIR spectra did not show any changes compared to the untreated films, meaning that polymers maintain their structural integrity at high temperature. Ó 1999 Elsevier Science S.A. All rights reserved. Y1 - 1999 ER - TY - JOUR A1 - Okatova, Olga V. A1 - Andreeva, Katharina A. A1 - Schulz, Burkhard A1 - Lavrenko, Peter N. T1 - Degradation of poly(m-phenylene oxadiazole) in concentrated sulfuric acid Y1 - 1999 ER - TY - JOUR A1 - Lavrenko, Peter N. A1 - Okatova, Olga V. A1 - Schulz, Burkhard A1 - Andreeva, Katharina A. A1 - Strelina, Irina A. T1 - Hydrodynamic and dynamo-optical properties of poly(1,3-phenylene-1,3,4-oxadiazole) molecules in sulphuric acid N2 - Translational diffusion of the macromolecules, intrinsic viscosity and flow birefringence induced in dilute solutions of poly(1,3-phenylene-1,3,4-oxadiazole) (PMOD) in conc. sulphuric acid has been investigated. Molecular-weight dependences of hydrodynamic and dynamo-optical properties are established over the M range from 8.1 103 to 87 103. Experimental data agree well with the theories developed for translational friction and intrinsic viscosity of the wormlike chains with the following molecular parameters: mass per chain unit ML = 22.7 Dalton/Å, the Kuhn segment length A = 59 ± 4 Å, the chain diameter d = 4 ± 1.5 Å. Hindrance to intramolecular rotation is characterized by the parameter s = 1.7. The shear optical coefficient was found to be approximately 1.7 times lower the value of that obtained in the same solvent for the para-phenylene isomer of this polymer, being in good agreement with higher equilibrium flexibility of the PMOD molecule chains in solutions as determined herein from the hydrodynamic data. Y1 - 1999 ER - TY - JOUR A1 - Reiche, Jürgen A1 - Freydank, Anke-Christine A1 - Helms, Andreas A1 - Geue, Thomas A1 - Schulz, Burkhard A1 - Brehmer, Ludwig A1 - Stiller, Burkhard A1 - Knochenhauer, Gerald T1 - Vacuum deposition films of oxadiazole compounds : formation and structure investigation N2 - The search for alternative routes of organic thin film formation is stimulated by the outstanding properties of these films in such fields as nonlinear optics, photonic data processing and molecular electronics. The formation of highly ordered multilayer structures by thermal vacuum deposition (VD) of organic compounds is an essential step toward the application of supramolecular organic architectures in technical systems. The VD of an amphiphilic substituted 2,5- diphenylene-1,3,4-oxadiazole 1 onto silicon substrates at defined temperature was used for the formation of ultrathin films. The structural data obtained for the VD-films of oxadiazole 1 by means of X-ray reflectivity, X-ray grazing incidence diffraction and atomic force microscopy (AFM) investigations indicate the formation of well ordered oxadiazole multilayers. The structure of the VD-multilayers is compared with that of Langmuir-Blodgett (LB) films and thermally treated LB-multilayers prepared from the same compound. Y1 - 1999 ER - TY - JOUR A1 - Lavrenko, Peter N. A1 - Andreeva, Katharina A. A1 - Strelina, Irina A. A1 - Garmonova, Tatjana I. A1 - Schulz, Burkhard T1 - Optical anisotropy and flexibility of poly(m-phenylene oxadiazole) in sulfuric acid Y1 - 1999 ER - TY - JOUR A1 - Orgzall, Ingo A1 - Lorenz, Bernd A1 - Mikat, Jürgen E. R. A1 - Reck, Günter A1 - Knochenhauer, Gerald A1 - Schulz, Burkhard T1 - Phase transition in 1,3,4-oxadiazole crystals under high pressure N2 - Crystalline 2,5-di(4-nitrophenyl)-1,3,4-oxadiazole (DNO) has been investigated at pressures up to 5 GPa using Raman and optical spectroscopy as well as energy dispersive X-ray techniques. At ambient pressure DNO shows an orthorhombic unit cell (a = 0.5448 nm, b = 1.2758 nm, c = 1.9720 nm, density 1.513 g cm-3) with an appropriate space group Pbcn. From Raman spectroscopic investigations three phase transitions have been detected at 0.88, 1.28, and 2.2 GPa, respectively. These transitions have also been confirmed by absorption spectroscopy and X-ray measurements. Molecular modeling simulations have considerably contributed to the interpretation of the X-ray diffractograms. In general, the nearly flat structure of the oxadiazole molecule is preserved during the transitions. All subsequent structures are characterized by a stack-like arrangement of the DNO molecules. Only the mutual position of these molecular stacks changes due to the transformations so that this process may be described as a topotactical reaction. Phases II and III show a monoclinic symmetry with space group P21/c with cell parameters a = 1.990 nm, b = 0.500 nm, c = 1.240 nm, ß = 91.7°, density 1.681 g cm-3 (phase II, determined at 1. 1 GPa) and a = 1.890 nm, b = 0.510 nm, C = 1.242 nm, ß = 89.0°, density 1.733 g cm-3 (phase 111, determined at 2.0 GPa), respectively. The high-pressure phase IV stable at least up to 5 GPa shows again an orthorhombic structure with space group Pccn with corresponding cell parameters at 2.9 GPa: a = 0.465 nm, b = 1.920 nm, c = 1.230 nm and density 1.857 g cm-3 . For the first phase a blue pressure shift of the onset of absorption by about 0.032 eV GPa has been observed that may be explained by pressure influences on the electronic conjugation of the molecule. In the intermediate and high-pressure phases II-IV the onset of absorption shifts to increased wavelengths due to larger intermolecular interactions and enhanced excitation delocalization with decreasing intermolecular spacing. Y1 - 1999 ER - TY - JOUR A1 - Schürmann, H. A1 - Koch, Norbert A1 - Imperia, Paolo A1 - Schrader, Sigurd A1 - Jandke, M. A1 - Strohriegl, P. A1 - Schulz, Burkhard A1 - Leising, G. A1 - Brehmer, Ludwig T1 - Ultraviolet photoelectron spectroscopic study of heterocyclic model compounds for electroluminescent devices Y1 - 1999 ER - TY - JOUR A1 - Mikat, Jürgen E. R. A1 - Franco, Olga A1 - Regenstein, Wolfgang A1 - Reck, Günter A1 - Knochenhauer, Gerald A1 - Schulz, Burkhard A1 - Orgzall, Ingo T1 - 1,3,4-oxadiazole crystals under high pressure-phase transitions and properties Y1 - 2000 ER - TY - JOUR A1 - Kaminorz, Yvette A1 - Schulz, Burkhard A1 - Brehmer, Ludwig T1 - Optical and Electrical Properties of Substituted 2,5-Diphenyl-1,3,4-Oxadiazoles N2 - New substituted 2,5-diphenyl-1,3,4-oxadiazoles are reported as luminescent materials in light emitting diodes LEDs . The investigated new oxadiazoles show efficient blue and green emission in single layer devices. The combination with a hole transporting and red emitting polythiophene led to a white emission with higher quantum efficiency (QE). Y1 - 2000 ER - TY - JOUR A1 - Karageorgiev, Peter A1 - Stiller, Burkhard A1 - Prescher, Dietrich A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Brehmer, Ludwig T1 - Modification of the surface potential of azobenzene-containing langmuir-blodgett films in the near field of a scanning kelvin microscope tip by irradiation Y1 - 2000 ER - TY - JOUR A1 - Hamaciuc, E. A1 - Bruma, Maria A1 - Köpnick, Thomas A1 - Kaminorz, Yvette A1 - Schulz, Burkhard T1 - Synthesis and Study of New Silicon-containing Polyoxadiazoles N2 - A series of new poly-1,3,4-oxadiazoles has been synthesized by polycondensation reaction of hydrazine sulfate with a mixture of a dicarboxylic acid containing unsaturated bonds and a dicarboxylic acid containing silicon, by using methanesulfonic acid/phosphorus pentoxide as a reaction medium. These polymers were highly thermostable but they were only soluble in strong inorganic acids such as sulfuric or methanesulfonic ones. An alternative way was followed by using the corresponding dihydrazides containing unsaturated bonds and the corresponding diacid chloride containing silicon that reacted in N-methylpyrrolidinone (NMP) to give soluble silicon-containing unsaturated polyhydrazides, which were cyclodehydrated either by thermal or chemical treatment to give the corresponding polyoxadiazoles. Very thin coatings of polyhydrazides and polyoxadiazoles were deposited onto silicon wafers and they showed a very smooth surface, free of pinholes, when studied by atomic force microscopy (AFM). Some polyoxadiazole films showed strong blue photoluminescence. Y1 - 2001 ER - TY - JOUR A1 - Lohwaßer, Roswitha A1 - Haßler, Gerda A1 - Behrmann, Günter C. A1 - Schulz, Burkhard A1 - Mieske, Silvio T1 - Portal = Knappe Kassen: Was das akademische Jahr bringt BT - Die Potsdamer Universitätszeitung N2 - Aus dem Inhalt: - Knappe Kassen: Was das akademische Jahr bringt - Sparkasse finanziert Stiftungsprofessur - Chipkarte ersetzt Studentenausweis aus Papier - Unikonzert im Potsdamer Nikolaisaal T3 - Portal: Das Potsdamer Universitätsmagazin - 08-10/2003 Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-502262 SN - 1618-6893 VL - 2003 ER - TY - JOUR A1 - Diez, Isabel A1 - Tauer, Klaus A1 - Schulz, Burkhard T1 - Polypyrrole tubes via casting of pyrrole-beta-naphthalenesulfonic acid rods N2 - A comprehensive study gives experimental evidence that a complex made from pyrrole and beta-naphthalenesulfonic acid in a molar composition of 3:1 acts as morphological precursor in the subsequent oxidative polymerization of pyrrole initiated with ammonium peroxodisulfate. The precursor complex itself is unable to polymerize but its outer parallelepipedal shape with a high aspect ratio is templated in the inner surface of the formed conducting polypyrrole tubes Y1 - 2004 SN - 0303-402X ER - TY - JOUR A1 - Karageorgiev, Peter A1 - Neher, Dieter A1 - Schulz, Burkhard A1 - Stiller, Burkhard A1 - Pietsch, Ullrich A1 - Giersig, Michael A1 - Brehmer, Ludwig T1 - From anisotropic photo-fluidity towards nanomanipulation in the optical near-field N2 - An increase in random molecular vibrations of a solid owing to heating above the melting point leads to a decrease in its long-range order and a loss of structural symmetry. Therefore conventional liquids are isotropic media. Here we report on a light-induced isothermal transition of a polymer film from an isotropic solid to an anisotropic liquid state in which the degree of mechanical anisotropy can be controlled by light. Whereas during irradiation by circular polarized light the film behaves as an isotropic viscoelastic fluid, it shows considerable fluidity only in the direction parallel to the light field vector under linear polarized light. The fluidization phenomenon is related to photoinduced motion of azobenzene-functionalized molecular units, which can be effectively activated only when their transition dipole moments are oriented close to the direction of the light polarization. We also describe here how the photofluidization allows nanoscopic elements of matter to be precisely manipulated Y1 - 2005 SN - 1476-1122 ER - TY - JOUR A1 - Sava, Ion A1 - Bruma, Maria A1 - Schulz, Burkhard A1 - Köpnick, Thomas T1 - Comparison of properties of silicon-containing poly(amide-imide)s N2 - New silicon-containing poly(amide-imide)s have been synthesized by direct polycondensation of various aromatic diamines with a dicarboxylic acid containing the dimethylsilylene group and preformed in-tide cycles. These polymers are easily soluble in polar amidic solvents such as N-methylpyrrolidinone (NMP) or dimethylformamide (DMF) and can be cast into thin flexible films or coatings from such solutions. They show high thermal stability, with initial decomposition temperature being above 400 C and glass transition temperature in the range of 220-270 degrees C. Very thin polymer films deposited by spincoating technique onto silicon wafers showed a smooth, pinhole-free surface in atomic force microscopy investigations Y1 - 2005 SN - 0954-0083 ER - TY - BOOK A1 - Schulz, Burkhard A1 - Orgzall, Ingo A1 - Freydank, Anke-Christine A1 - Chenggang, Xü T1 - Self-organization of substituted 1,3,4-oxadizazoles in the solid state and at surfaces N2 - Different aspects of the structure formation for a class of molecules containing the diphenyl-1,3,4-oxadiazole fragment are discussed. Starting from the bulk state with the ideal crystal lattice and the derivation of some common packing motifs the formation of liquid-crystalline states are described. This leads to the consideration of structures found in Langmuir-Blodgett films and those obtained by organic molecular beam deposition. These structures may again be compared to those for the bulk crystalline state. Common features as well as characteristic differences due to peculiarities of the individual molecular structures are discussed. (c) 2005 Elsevier B.V. All rights reserved Y1 - 2005 ER - TY - JOUR A1 - Franco, Olga A1 - Orgzall, Ingo A1 - Reck, Günter A1 - Stockhause, Sabine A1 - Schulz, Burkhard T1 - Structure and high-pressure behavior of 2,5-di-(4-aminophenyl)-1,3,4-oxadiazole N2 - The crystalline structures of two modifications of a compound containing the oxadiazole ring, 2,5-di-(4- aminophenyl)-1,3,4-oxadiazole (DAPO) were determined. One of these modifications contains water molecules in the crystal structure, which is observed for the first time for an oxadiazole crystal. Both crystals show an orthorhombic structure. The water free modification, DAPO L belongs to the space group Pbca (61) and has the lattice parameters: a = 13.461(5), b = 7.937(3) and c = 22.816(8) angstrom (CCDC 246608). The water containing pseudo-polymorph, DAPO 11, has the space group Cmcm (63) and the lattice parameters: a = 16.330(5), b = 12.307(2) and c = 6.9978(14) angstrom (CCDC 246609). To gain information on the inter molecular interactions within the crystals, X-ray experiments under compression at ambient temperature and under heating at vacuum conditions were performed. Neither DAPO I nor DAPO II undergo phase transitions in the ressure range up to 5 GPa, as could be concluded from X-ray and Raman experiments. X-ray and calorimetric studies indicate that DAPO II dehydrates into DAPO I under increasing temperature. Structural considerations suggest a two-stage process. The compression behavior of both substances is well described by the Murnaghan equation of state (MEOS) and the values of the bulk modulus and its pressure derivative are determined for these crystals. Additionally, in the case of DAPO I, also the thermal expansion coefficient an was measured. (c) 2005 Elsevier Ltd. All rights reserved Y1 - 2005 SN - 0022-3697 ER - TY - JOUR A1 - Orgzall, Ingo A1 - Franco, Olga A1 - Reck, Guenter A1 - Schulz, Burkhard T1 - High-pressure studies on fluorine substituted 2,5-di(phenyl)-1,3,4-oxadiazoles N2 - Results are presented from structural and high-pressure investigations on four differently but symmetrically fluorine substituted 2,5di(phenyl)-1,3,4-oxadiazoles. The substitution pattern includes the para-, meta-, or ortho- substitution and the fully fluorinated 2,5-bis(pentafluorophenyl)-1,3,4-oxadiazole. The crystal structure depends on the molecular structure and results in a different high-pressure behavior. Parameters for the Murnaghan equation of state (EOS) are determined for every compound and the anisotropic pressure response of the crystal lattice is discussed. Although the EOS parameters, bulk modulus K. and its pressure derivative K'(o) are of the same order of magnitude for all four compounds, the anisotropy of strain is noticeably different. (c) 2005 Elsevier B.V. All rights reserved Y1 - 2005 SN - 0022-2860 ER - TY - JOUR A1 - Diez, Isabel A1 - Tauer, Klaus A1 - Schulz, Burkhard T1 - Unusual polymer dispersions-polypyrrole suspensions made of rings, frames, and platelets JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - Experimental results show that the polymerization of pyrrole in the presence of beta-naphthalenesulfonic acid and different fluorosurfactants like perfluorooctanesulfonic acid, perfluorooctyldiethanolamide, and ammonium perfluorooctanoate leads to polypyrrole with special morphologies, such as rings or disks and rectangular frames or plates. The formation of these unusually shaped particles of polymer dispersions is explained by the chemical and colloidal peculiarities of the oxidative pyrrole polymerization with ammonium peroxodisulfate in aqueous medium. KW - polypyrrole KW - chemical oxidative polymerization KW - particle morphology Y1 - 2006 U6 - https://doi.org/10.1007/s00396-006-1521-8 SN - 0303-402X VL - 284 SP - 1431 EP - 1442 PB - Springer CY - New York ER - TY - JOUR A1 - Franco, Olga A1 - Orgzall, Ingo A1 - Regenstein, Wolfgang A1 - Schulz, Burkhard T1 - Structural and spectroscopical study of a 2,5-diphenyl-1,3,4-oxadiazole polymorph under compression N2 - The x-ray pattern and the Raman and luminescence spectra of crystalline 2,5-diphenyl-1,3,4-oxadiazole in one of its polymorphic forms (DPO II) have been investigated under pressure up to 5 GPa. The behaviour of the lattice parameters under compression was determined and it was found that the Murnaghan equation of state provides a good description of the volume-pressure relationship of DPO II. The values for the bulk modulus and its pressure derivative are K-0 = 8.6 GPa and K-0' = 7.2. The analysis of the Raman spectrum under compression clearly shows the pressure- induced shift of the Raman modes to higher frequencies. The mode Gruneisen parameters for the lattice modes were determined. Additionally, it was found that the emission spectrum of DPO II moves to lower energies and that the luminescence intensity decreases when pressure is applied Y1 - 2006 UR - http://iopscience.iop.org/0953-8984 U6 - https://doi.org/10.1088/0953-8984/18/4/029 SN - 0953-8984 ER - TY - JOUR A1 - Orgzall, Ingo A1 - Franco, Olga A1 - Schulz, Burkhard T1 - High pressure structural investigations of 2,5-di(4-pyridyl)-1,3,4-oxadiazole - importance of strain studies for the description of intermolecular interactions N2 - Results of a high pressure x-ray study of 2,5-di(4-pyridyl)-1,3,4-oxadiazole up to 2.5 GPa are presented and discussed. Parameters for the Murnaghan equation of state are derived. The bulk modulus amounts to K-0 = 4.6 +/- 0.3 GPa and its pressure derivative to K-0' = 7.4 +/- 0.6. These values are comparable to values of other diphenyl-1,3,4- oxadiazoles. The anisotropy of the compression is analysed using the strain tensor and discussed based on the anisotropy of the intermolecular interactions Y1 - 2006 UR - http://iopscience.iop.org/0953-8984 U6 - https://doi.org/10.1088/0953-8984/18/23/001 ER - TY - JOUR A1 - Emmerling, Franziska A1 - Orgzall, Ingo A1 - Reck, Günter A1 - Schulz, Burkhard W. A1 - Stockhause, Sabine A1 - Schulz, Burkhard T1 - Structures of substituted di-aryl-1, 3,4-oxadiazole derivatives: 2,5-bis(pyridyl)- and 2,5-bis(aminophenyl)-substitution JF - Journal of molecular structure N2 - Crystal structures of four different di-aryl-1,3,4-oxadiazole compounds (aryl = 2-pyridyl-, 3-pyridyl-, 2-aminophenyl-, 3-aminophenyl-) are determined. Crystallization of di(2-pyridyl)-1,3,4-oxadiazole yielded monoclinic and triclinic polymorphs. The structures are characterized by the occurrence of pi-pi interactions. Additionally, in case of the aminophenyl compounds intra- as well as intermolecular hydrogen bonds are found that influence the packing motif as well. Since these molecules are often used as ligands in metal-organic complexes similarities and differences of the molecular conformation between the molecules in the pure crystals and that of the ligands in the complexes are discussed. (c) 2006 Elsevier B.V. All rights reserved. KW - crystal structure KW - 1,3,4-oxadiazole KW - molecular conformation KW - hydrogen bonds Y1 - 2006 U6 - https://doi.org/10.1016/j.molstruc.2006.03.076 SN - 0022-2860 VL - 800 IS - 1-3 SP - 74 EP - 84 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schulz, Burkhard A1 - Dietzel, Birgit A1 - Orgzall, Ingo A1 - Diez, Isabel A1 - Xu, Chenggang T1 - Aspects of morphology control during the oxidative synthesis of electrically conducting polymers N2 - The formation of micro- and nanostructures during the oxidative polymerization of polypyrrole and polyaniline is investigated using different sulfonic acid dopants. Rod- or tube-like structures are found in polypyrrole as well as in polyaniline without addition of further compounds to the initial reaction mixture of monomer, dopant and oxidant. In these cases, always a crystalline precursor complex composed of a dopand molecule and the pure monomer (aniline) or a trimeric moiety (pyrrole) serves as in-situ template. In most cases the surface of the growing polymer is covered by secondary structures with much smaller sizes so that a hierarchical order of structures at different length scales results. Corresponding model considerations for the polymerization process are outlined. Additionally, unusual structures like platelets, frames, rings, or ribbons are observed in the polypyrrole synthesis in the presence of fluorosurfactants. Y1 - 2009 UR - http://hip.sagepub.com/ U6 - https://doi.org/10.1177/0954008309339933 SN - 0954-0083 ER - TY - JOUR A1 - Sarac, A. Sezai A1 - Gencturk, Asli A1 - Gilsing, Hans-Detlev A1 - Schulz, Burkhard A1 - Turhan, C. Metehan T1 - Effect of electrolyte on the electropolymerization of 2,2-dibutyl-3,4-propylenedioxythiophene on carbon fiber microelectrodes N2 - Electrocoating of 2,2 dibutylpropylene dioxythiophene on carbon fiber microelectrodes (CFMEs) in different electrolytes in acetonitrile was performed, and surface morphology and electrochemical impedance spectroscopic investigation has been carried out. Impedance spectra showed the typical form of Z(IM) versus Z(RE) for transmission- line at frequencies 10 Hz, with transition to almost pure capacitive behaviour down to 10 mHz (the lower limit of frequency scan). Y1 - 2009 UR - http://aspbs.com/jnn/ U6 - https://doi.org/10.1166/Jnn.2009.027 SN - 1533-4880 ER - TY - JOUR A1 - Schulz, Burkhard A1 - Orgzall, Ingo A1 - Diez, Isabel A1 - Dietzel, Birgit A1 - Tauer, Klaus T1 - Template mediated formation of shaped polypyrrole particles N2 - The formation of different micro- and nanostructures during the chemical synthesis of polypyrrole is reviewed shortly based on the conceptions of hard- and soft-templating models. Contrary to other models that emphasize the role of micelles it is found here that during the oxidative polymerization of pyrole using sulfonic acid dopants a crystalline hard template is found in the first steps of the reaction before the addition of the oxidant. This template is formed by a complex consisting of 2,5-bis(pyrrole-2-yl)pyrrolidine and the sulfonic acid anion. The acid catalyzed formation of this specific tripyrrole is discussed. (C) 2009 Elsevier B.V. All rights reserved. Y1 - 2010 U6 - https://doi.org/10.1016/j.colsurfa.2009.11.034 SN - 0927-7757 ER - TY - JOUR A1 - Hoffmann, Katrin A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Reck, Guenter A1 - Hoffmann, Angelika A1 - Orgzall, Ingo A1 - Resch-Genger, Ute A1 - Emmerling, Franziska T1 - Combined structural and fluorescence studies of methyl-substituted 2,5-diphenyl-1,3,4-oxadiazoles - Relation between electronic properties and packing motifs JF - Journal of molecular structure N2 - Prerequisite for the rational design of functional organic materials with tailor-made electronic properties is the knowledge of the structure-property relationship for the specific class of molecules under consideration. This encouraged us to systematically study the influence of the molecular structure and substitution pattern of aromatically substituted 1,3,4-oxadiazoles on the electronic properties and packing motifs of these molecules and on the interplay of these factors. For this purpose, seven diphenyl-oxadiazoles equipped with methyl substituents in the ortho- and meta-position(s) were synthesized and characterized. Absorption and fluorescence spectra in solution served here as tools to monitor substitution-induced changes in the electronic properties of the individual molecules whereas X-ray and optical measurements in the solid state provided information on the interplay of electronic and packing effects. In solution, the spectral position of the absorption maximum, the size of Stokes shift, and the fluorescence quantum yield are considerably affected by ortho-substitution in three or four ortho-positions. This results in blue shifted absorption bands, increased Stokes shifts, and reduced fluorescence quantum yields whereas the spectral position and vibrational structure of the emission bands remain more or less unaffected. In the crystalline state, however, the spectral position and shape of the emission bands display a strong dependence on the molecular structure and/or packing motifs that seem to control the amount of dye-dye-interactions. These observations reveal the limited value of commonly reported absorption and fluorescence measurements in solution for a straightforward comparison of spectroscopic results with single X-ray crystallography. This underlines the importance of solid state spectroscopic studies for a better understanding of the interplay of electronic effects and molecular order. KW - Diphenyl-oxadiazoles KW - X-ray structure KW - Packing motif KW - Optical properties KW - Fluorescence quantum yield Y1 - 2011 U6 - https://doi.org/10.1016/j.molstruc.2010.11.071 SN - 0022-2860 VL - 988 IS - 1-3 SP - 35 EP - 46 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Banks, Jo Ann A1 - Nishiyama, Tomoaki A1 - Hasebe, Mitsuyasu A1 - Bowman, John L. A1 - Gribskov, Michael A1 - dePamphilis, Claude A1 - Albert, Victor A. A1 - Aono, Naoki A1 - Aoyama, Tsuyoshi A1 - Ambrose, Barbara A. A1 - Ashton, Neil W. A1 - Axtell, Michael J. A1 - Barker, Elizabeth A1 - Barker, Michael S. A1 - Bennetzen, Jeffrey L. A1 - Bonawitz, Nicholas D. A1 - Chapple, Clint A1 - Cheng, Chaoyang A1 - Correa, Luiz Gustavo Guedes A1 - Dacre, Michael A1 - DeBarry, Jeremy A1 - Dreyer, Ingo A1 - Elias, Marek A1 - Engstrom, Eric M. A1 - Estelle, Mark A1 - Feng, Liang A1 - Finet, Cedric A1 - Floyd, Sandra K. A1 - Frommer, Wolf B. A1 - Fujita, Tomomichi A1 - Gramzow, Lydia A1 - Gutensohn, Michael A1 - Harholt, Jesper A1 - Hattori, Mitsuru A1 - Heyl, Alexander A1 - Hirai, Tadayoshi A1 - Hiwatashi, Yuji A1 - Ishikawa, Masaki A1 - Iwata, Mineko A1 - Karol, Kenneth G. A1 - Koehler, Barbara A1 - Kolukisaoglu, Uener A1 - Kubo, Minoru A1 - Kurata, Tetsuya A1 - Lalonde, Sylvie A1 - Li, Kejie A1 - Li, Ying A1 - Litt, Amy A1 - Lyons, Eric A1 - Manning, Gerard A1 - Maruyama, Takeshi A1 - Michael, Todd P. A1 - Mikami, Koji A1 - Miyazaki, Saori A1 - Morinaga, Shin-ichi A1 - Murata, Takashi A1 - Müller-Röber, Bernd A1 - Nelson, David R. A1 - Obara, Mari A1 - Oguri, Yasuko A1 - Olmstead, Richard G. A1 - Onodera, Naoko A1 - Petersen, Bent Larsen A1 - Pils, Birgit A1 - Prigge, Michael A1 - Rensing, Stefan A. A1 - Mauricio Riano-Pachon, Diego A1 - Roberts, Alison W. A1 - Sato, Yoshikatsu A1 - Scheller, Henrik Vibe A1 - Schulz, Burkhard A1 - Schulz, Christian A1 - Shakirov, Eugene V. A1 - Shibagaki, Nakako A1 - Shinohara, Naoki A1 - Shippen, Dorothy E. A1 - Sorensen, Iben A1 - Sotooka, Ryo A1 - Sugimoto, Nagisa A1 - Sugita, Mamoru A1 - Sumikawa, Naomi A1 - Tanurdzic, Milos A1 - Theissen, Guenter A1 - Ulvskov, Peter A1 - Wakazuki, Sachiko A1 - Weng, Jing-Ke A1 - Willats, William W. G. T. A1 - Wipf, Daniel A1 - Wolf, Paul G. A1 - Yang, Lixing A1 - Zimmer, Andreas D. A1 - Zhu, Qihui A1 - Mitros, Therese A1 - Hellsten, Uffe A1 - Loque, Dominique A1 - Otillar, Robert A1 - Salamov, Asaf A1 - Schmutz, Jeremy A1 - Shapiro, Harris A1 - Lindquist, Erika A1 - Lucas, Susan A1 - Rokhsar, Daniel A1 - Grigoriev, Igor V. T1 - The selaginella genome identifies genetic changes associated with the evolution of vascular plants JF - Science N2 - Vascular plants appeared similar to 410 million years ago, then diverged into several lineages of which only two survive: the euphyllophytes (ferns and seed plants) and the lycophytes. We report here the genome sequence of the lycophyte Selaginella moellendorffii (Selaginella), the first nonseed vascular plant genome reported. By comparing gene content in evolutionarily diverse taxa, we found that the transition from a gametophyte- to a sporophyte-dominated life cycle required far fewer new genes than the transition from a nonseed vascular to a flowering plant, whereas secondary metabolic genes expanded extensively and in parallel in the lycophyte and angiosperm lineages. Selaginella differs in posttranscriptional gene regulation, including small RNA regulation of repetitive elements, an absence of the trans-acting small interfering RNA pathway, and extensive RNA editing of organellar genes. Y1 - 2011 U6 - https://doi.org/10.1126/science.1203810 SN - 0036-8075 VL - 332 IS - 6032 SP - 960 EP - 963 PB - American Assoc. for the Advancement of Science CY - Washington ER - TY - JOUR A1 - Turhan, Metehan C. A1 - Sarac, A. Sezai A1 - Gencturk, Asli A1 - Gilsing, Hans-Detlev A1 - Faltz, Heike A1 - Schulz, Burkhard T1 - Electrochemical impedance characterization and potential dependence of poly[3,4-(2,2-dibutylpropylenedioxy)thiophene] nanostructures on single carbon fiber microelectrode JF - Synthetic metals : the journal of electronic polymers and electronic molecular materials N2 - The electropolymerization of 3,4-(2,2-dibutylpropylenedioxy)thiophene (ProDOT-Bu-2) onto single carbon fiber microelectrode (SCFME) was conducted in acetonitrile (ACN) containing sodium perchlorate (NaClO4) as electrolyte and investigated by cyclic voltammetry (CV). The nanostructured films of poly[3,4-(2,2-dibutyl-propyleneclioxy)thiophene] (PProDOT-Bu-2) which were depositing showed complete reversible redox behavior in monomer-free electrolyte solution. The capacitive behavior of the films was investigated by electrochemical impedance spectroscopy (EIS) at applied potentials from 0.1 V to 1.3 V. The analysis by equivalent circuit modeling revealed an applied potential around 0.4V to be most suitable for the system PProDOT-Bu-2/SCFME as a double layer supercapacitor component inducing a double layer capacitance C-d, value of 62 mFcm(-2). KW - Nanostructure KW - Electrochemical impedance spectroscopy KW - Conjugated polymeric thin film KW - Carbon fiber Y1 - 2012 U6 - https://doi.org/10.1016/j.synthmet.2012.01.012 SN - 0379-6779 VL - 162 IS - 5-6 SP - 511 EP - 515 PB - Elsevier CY - Lausanne ER - TY - JOUR A1 - Guler, Fatma G. A1 - Gilsing, Hans-Detlev A1 - Schulz, Burkhard A1 - Sarac, A. Sezai T1 - Impedance and morphology of hydroxy- and chloro-functionalized poly(3,4-propylenedioxythiophene) nanostructures JF - Journal of nanoscience and nanotechnolog N2 - The new 3,4-propylenedioxythiophenes (ProDOT) bearing hydroxy- or chloro-functionalized side chains of varying length and polarity were synthesized and electropolymerized on single carbon fiber microelectrode (SCFME) using cyclo-voltammetry. Electrochemical impedance spectroscopy (EIS) revealed highest capacitance values for the hydroxy-functionalized Poly 5 carrying a side chain of medium length. The EIS data were fitted with an equivalent electrical circuit giving a good correlation. AFM analysis of the topography showed higher roughness values for Poly 5 than for the two other polymers bearing longer side chains. Due to their reactive end groups the polymers should be useful for post-polymerization functionalization of the electrode surface. KW - 3,4-Propylenedioxythiophene KW - Electroactive Conjugated Polymer KW - EIS KW - AFM Y1 - 2012 U6 - https://doi.org/10.1166/jnn.2012.6594 SN - 1533-4880 VL - 12 IS - 10 SP - 7869 EP - 7878 PB - American Scientific Publ. CY - Valencia ER - TY - JOUR A1 - Emmerling, Franziska A1 - Orgzall, Ingo A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Larrucea, Julen T1 - Ordering the amorphous - Structures in PBD LED materials JF - Journal of molecular structure N2 - The class of 2,5 disubstituted-1,3,4-oxadiazoles containing a biphenyl unit on one side is intensively used as electron transport materials to enhance the performance of organic light emitting diodes (OLEDs). In contrast to the ongoing research on these materials insights in their structure-property relationships are still incomplete. To overcome the structural tentativeness and ambiguities the crystal structures of 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, that of the related compound 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole and of 2-(4-biphenylyl)-5-(2,6-dimethylphenyl)-1,3,4-oxadiazole are determined. A comparison with the results of GAUSSIAN03 calculations and similar compounds in the Cambridge Structural Database leads to a profound characterization. KW - OLED KW - PBD KW - Diphenyl-1,3,4-oxadiazole KW - Crystallization Y1 - 2012 U6 - https://doi.org/10.1016/j.molstruc.2012.04.040 SN - 0022-2860 VL - 1030 IS - 23 SP - 209 EP - 215 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Sarauli, David A1 - Xu, Chenggang A1 - Dietzel, Birgit A1 - Stiba, Konstanze A1 - Leimkühler, Silke A1 - Schulz, Burkhard A1 - Lisdat, Fred T1 - Thin films of substituted polyanilines interactions with biomolecular systems JF - Soft matter N2 - We use substituted polyanilines for the construction of new polymer electrodes for interaction studies with the redox protein cytochrome c (cyt c) and the enzyme sulfite oxidase (SO). For these purposes four different polyaniline copolymers are chemically synthesized. Three of them are copolymers, containing 2-methoxyaniline-5-sulfonic acid with variable ratios of aniline; the fourth copolymer consists of 3-amino-benzoic acid and aniline. The results show that all polymers are suitable for being immobilized as thin stable films on gold wire and indium tin oxide (ITO) electrode surfaces from DMSO solution. This can be demonstrated by cyclic voltammetry and UV-Vis spectroscopy measurements. Moreover, cyt c can be electrochemically detected not only in solution, but also immobilized on top of the polymer films. Furthermore, the appearance of a significant catalytic current has been demonstrated for the sulfonated polyanilines, when the polymer-coated protein electrode is being measured upon addition of sulfite oxidase, confirming the establishment of a bioanalytical signal chain. Best results have been obtained for the polymer with highest sulfonation grade. The redox switching of the polymer by the enzymatic reaction can also be analyzed by following the spectral properties of the polymer electrode. Y1 - 2012 U6 - https://doi.org/10.1039/c2sm07261k SN - 1744-683X VL - 8 IS - 14 SP - 3848 EP - 3855 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Sarauli, David A1 - Xu, Chenggang A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Lisdat, Fred T1 - Differently substituted sulfonated polyanilines - the role of polymer compositions in electron transfer with pyrroloquinoline quinone-dependent glucose dehydrogenase JF - Acta biomaterialia N2 - Sulfonated polyanilines have become promising building blocks in the construction of biosensors, and therefore we use here differently substituted polymer forms to investigate the role of their structural composition and properties in achieving a direct electron transfer with the redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH). To this end, new copolymers containing different ratios of 2-methoxyaniline-5-sulfonic acid (MAS), 3-aminobenzenesulfonic acid (ABS) and 3-aminobenzoic acid (AB) units have been chemically synthesized. All polymers have been studied with respect to their ability to react directly with PQQ-GDH. This interaction has been monitored initially in solution, and subsequently on electrode surfaces. The results show that only copolymers with MAS and aniline units can directly react with PQQ-GDH in solution; the background can be mainly ascribed to the emeraldine salt redox state of the polymer, allowing rather easy reduction. However, when polymers and the enzyme are immobilized on the surface of carbon nanotube-containing electrodes, direct bioelectrocatalysis is also feasible in the case of copolymers composed of ABS/AB and MAS/AB units, existing initially in pernigraniline base form. This verifies that a productive interaction of the enzyme with differently substituted polymers is feasible when the electrode potential can be used to drive the reaction towards the oxidation of the substrate-reduced enzyme. These results clearly demonstrate that enzyme electrodes based on sulfonated polyanilines and direct bioelectrocatalysis can be successfully constructed. KW - Sulfonated polyaniline KW - PQQ-dependent glucose dehydrogenase KW - Direct electron transfer KW - Immobilization KW - Bioelectrocatalysis Y1 - 2013 U6 - https://doi.org/10.1016/j.actbio.2013.06.008 SN - 1742-7061 VL - 9 IS - 9 SP - 8290 EP - 8298 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Sarauli, David A1 - Xu, Chenggang A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Lisdat, Fred T1 - A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase: tunable direct bioelectrocatalysis JF - Journal of materials chemistry : B, Materials for biology and medicine N2 - A feasible approach to construct multilayer films of sulfonated polyanilines - PMSA1 and PABMSA1 containing different ratios of aniline, 2-methoxyaniline-5-sulfonic acid (MAS) and 3-aminobenzoic acid (AB), with the entrapped redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) on Au and ITO electrode surfaces, is described. The formation of layers has been followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrates that the multilayer assembly can be achieved in a progressive and uniform manner. The gold and ITO electrodes subsequently modified with PMSA1:PQQ-GDH and PABMSA1 films are studied by cyclic voltammetry (CV) and UV-Vis spectroscopy which show a significant direct bioelectrocatalytical response to the oxidation of the substrate glucose without any additional mediator. This response correlates linearly with the number of deposited layers. Furthermore, the constructed polymer/enzyme multilayer system exhibits a rather good long-term stability, since the catalytic current response is maintained for more than 60% of the initial value even after two weeks of storage. This verifies that a productive interaction of the enzyme embedded in the film of substituted polyaniline can be used as a basis for the construction of bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction. Y1 - 2014 U6 - https://doi.org/10.1039/c4tb00336e SN - 2050-750X SN - 2050-7518 VL - 2 IS - 21 SP - 3196 EP - 3203 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Sarauli, David A1 - Peters, Kristina A1 - Xu, Chenggang A1 - Schulz, Burkhard A1 - Fattakhova-Rohlfing, Dina A1 - Lisdat, Fred T1 - 3D-Electrode architectures for enhanced direct bioelectrocatalysis of pyrroloquinoline quinone-dependent glucose dehydrogenase JF - ACS applied materials & interfaces N2 - We report on the fabrication of a complex electrode architecture for efficient direct bioelectrocatalysis. In the developed procedure, the redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase entrapped in a sulfonated polyaniline [poly(2-methoxyaniline-5-sulfonic acid)-co-aniline] was immobilized on macroporous indium tin oxide (macroITO) electrodes. The use of the 3D-conducting scaffold with a large surface area in combination with the conductive polymer enables immobilization of large amounts of enzyme and its efficient communication with the electrode, leading to enhanced direct bioelectrocatalysis. In the presence of glucose, the fabricated bioelectrodes show an exceptionally high direct bioelectrocatalytical response without any additional mediator. The catalytic current is increased more than 200-fold compared to planar ITO electrodes. Together with a high long-term stability (the current response is maintained for >90% of the initial value even after 2 weeks of storage), the transparent 3D macroITO structure with a conductive polymer represents a valuable basis for the construction of highly efficient bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction. KW - 3D electrode structures KW - macroITO KW - conductive polymer KW - PQQ-GDH KW - direct bioelectrocatalysis KW - bioelectrochemistry Y1 - 2014 U6 - https://doi.org/10.1021/am5046026 SN - 1944-8244 VL - 6 IS - 20 SP - 17887 EP - 17893 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schöne, Anne-Christin A1 - Schulz, Burkhard A1 - Richau, Klaus A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Characterization of Langmuir films prepared from copolyesterurethanes based on oligo(omega-pentadecalactone) and oligo(epsilon-caprolactone)segments JF - Macromolecular chemistry and physics N2 - A series of multiblock copolymers (PDLCL) synthesized from oligo(omega-pentadecalactone) diol (OPDL) and oligo(epsilon-caprolactone) diol (OCL), which are linked by 2,2(4), 4-trimethyl-hexamethylene diisocyanate (TMDI), is investigated by the Langmuir monolayer technique at the air-water interface. Brewster angle microscopy (BAM) and spectroscopic ellipsometry are employed to characterize the polymer film morphologies in situ. PDLCL containing >= 40 wt% OCL segments form homogeneous Langmuir monofilms after spreading. The film elasticity modulus decreases with increasing amounts of OPDL segments in the copolymer. In contrast, the OCL-free polyesterurethane OPDL-TMDI cannot be spread to monomolecular films on the water surface properly, and movable slabs are observed by BAM even at low surface pressures. The results of the in situ morphological characterization clearly show that essential information concerning the reliability of Langmuir monolayer degradation (LMD) experiments cannot be obtained from the evaluation of the pi-A isotherms only. Consequently, in situ morphological characterization turns out to be indispensable for characterization of Langmuir layers before LMD experiments. KW - brewster angle microscopy KW - ellipsometry KW - Langmuir layers KW - morphology KW - polyesterurethanes Y1 - 2014 U6 - https://doi.org/10.1002/macp.201400377 SN - 1022-1352 SN - 1521-3935 VL - 215 IS - 24 SP - 2437 EP - 2445 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Sarauli, David A1 - Xu, Chenggang A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Lisdat, Fred T1 - A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase BT - tunable direct bioelectrocatalysis N2 - A feasible approach to construct multilayer films of sulfonated polyanilines – PMSA1 and PABMSA1 – containing different ratios of aniline, 2-methoxyaniline-5-sulfonic acid (MAS) and 3-aminobenzoic acid (AB), with the entrapped redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) on Au and ITO electrode surfaces, is described. The formation of layers has been followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrates that the multilayer assembly can be achieved in a progressive and uniform manner. The gold and ITO electrodes subsequently modified with PMSA1:PQQ-GDH and PABMSA1 films are studied by cyclic voltammetry (CV) and UV-Vis spectroscopy which show a significant direct bioelectrocatalytical response to the oxidation of the substrate glucose without any additional mediator. This response correlates linearly with the number of deposited layers. Furthermore, the constructed polymer/enzyme multilayer system exhibits a rather good long-term stability, since the catalytic current response is maintained for more than 60% of the initial value even after two weeks of storage. This verifies that a productive interaction of the enzyme embedded in the film of substituted polyaniline can be used as a basis for the construction of bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 275 Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-98744 ER - TY - JOUR A1 - Jetzschmann, Katharina J. A1 - Jagerszki, Gyula A1 - Dechtrirat, Decha A1 - Yarman, Aysu A1 - Gajovic-Eichelmann, Nenad A1 - Gilsing, Hans-Detlev A1 - Schulz, Burkhard A1 - Gyurcsanyi, Robert E. A1 - Scheller, Frieder W. T1 - Vectorially Imprinted Hybrid Nanofilm for Acetylcholinesterase Recognition JF - Advanced functional materials N2 - Effective recognition of enzymatically active tetrameric acetylcholinesterase (AChE) is accomplished by a hybrid nanofilm composed of a propidium-terminated self-assembled monolayer (Prop-SAM) which binds AChE via its peripheral anionic site (PAS) and an ultrathin electrosynthesized molecularly imprinted polymer (MIP) cover layer of a novel carboxylate-modified derivative of 3,4-propylenedioxythiophene. The rebinding of the AChE to the MIP/Prop-SAM nanofilm covered electrode is detected by measuring in situ the enzymatic activity. The oxidative current of the released thiocholine is dependent on the AChE concentration from approximate to 0.04 x 10(-6) to 0.4 x 10(-6)m. An imprinting factor of 9.9 is obtained for the hybrid MIP, which is among the best values reported for protein imprinting. The dissociation constant characterizing the strength of the MIP-AChE binding is 4.2 x 10(-7)m indicating the dominant role of the PAS-Prop-SAM interaction, while the benefit of the MIP nanofilm covering the Prop-SAM layer is the effective suppression of the cross-reactivity toward competing proteins as compared with the Prop-SAM. The threefold selectivity gain provided by i) the shape-specific MIP filter, ii) the propidium-SAM, iii) signal generation only by the AChE bound to the nanofilm shows promise for assessing AChE activity levels in cerebrospinal fluid. KW - acetylcholinesterase KW - biomimetic sensors KW - molecularly imprinted electropolymers KW - peripheral anionic site KW - propidium Y1 - 2015 U6 - https://doi.org/10.1002/adfm.201501900 SN - 1616-301X SN - 1616-3028 VL - 25 IS - 32 SP - 5178 EP - 5183 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schöne, Anne-Christin A1 - Richau, Klaus A1 - Kratz, Karl A1 - Schulz, Burkhard A1 - Lendlein, Andreas T1 - Influence of Diurethane Linkers on the Langmuir Layer Behavior of Oligo[(rac-lactide)-co-glycolide]-based Polyesterurethanes JF - Macromolecular rapid communications N2 - Three oligo[(rac-lactide)-co-glycolide] based polyesterurethanes (OLGA-PUs) containing different diurethane linkers are investigated by the Langmuir monolayer technique and compared to poly[(rac-lactide)-co-glycolide] (PLGA) to elucidate the influence of the diurethane junction units on hydrophilicity and packing motifs of these polymers at the air-water interface. The presence of diurethane linkers does not manifest itself in the Langmuir layer behavior both in compression and expansion experiments when monomolecular films of OLGA-PUs are spread on the water surface. However, the linker retard the evolution of morphological structures at intermediate compression level under isobaric conditions (with a surface pressure greater than 11 mN m(-1)) compared to the PLGA, independent on the chemical structure of the diurethane moiety. The layer thicknesses of both OLGA-PU and PLGA films decrease in the high compression state with decreasing surface pressure, as deduced from ellipsometric data. All films must be described with the effective medium approximation as water swollen layers. KW - Brewster angle microscopy KW - Langmuir monolayer KW - poly[(rac-lactide)-co-glycolide] KW - polyesterurethanes KW - spectroscopic ellipsometry Y1 - 2015 U6 - https://doi.org/10.1002/marc.201500316 SN - 1022-1336 SN - 1521-3927 VL - 36 IS - 21 SP - 1910 EP - 1915 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tanne, Johannes A1 - Jeoung, Jae-Hun A1 - Peng, Lei A1 - Yarman, Aysu A1 - Dietzel, Birgit A1 - Schulz, Burkhard A1 - Schad, Daniel A1 - Dobbek, Holger A1 - Wollenberger, Ursula A1 - Bier, Frank Fabian A1 - Scheller, Frieder W. T1 - Direct Electron Transfer and Bioelectrocatalysis by a Hexameric, Heme Protein at Nanostructured Electrodes JF - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis N2 - A nanohybrid consisting of poly(3-aminobenzenesulfonic acid-co-aniline) and multiwalled carbon nanotubes [MWCNT-P(ABS-A)]) on a gold electrode was used to immobilize the hexameric tyrosine-coordinated heme protein (HTHP). The enzyme showed direct electron transfer between the heme group of the protein and the nanostructured surface. Desorption of the noncovalently bound heme from the protein could be excluded by control measurements with adsorbed hemin on aminohexanthiol-modified electrodes. The nanostructuring and the optimised charge characteristics resulted in a higher protein coverage as compared with MUA/MU modified electrodes. The adsorbed enzyme shows catalytic activity for the cathodic H2O2 reduction and oxidation of NADH. KW - HTHP KW - Nanohybrid KW - Poylaniline KW - Multiwalled carbon nanotube Y1 - 2015 U6 - https://doi.org/10.1002/elan.201500231 SN - 1040-0397 SN - 1521-4109 VL - 27 IS - 10 SP - 2262 EP - 2267 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Rottke, Falko O. A1 - Schulz, Burkhard A1 - Richau, Klaus A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers JF - Beilstein journal of nanotechnology N2 - The applicability of nulling-based ellipsometric mapping as a complementary method next to Brewster angle microscopy (BAM) and imaging ellipsometry (IE) is presented for the characterization of ultrathin films at the air-water interface. First, the methodology is demonstrated for a vertically nonmoving Langmuir layer of star-shaped, 4-arm poly(omega-pentadecalactone) (PPDL-D4). Using nulling-based ellipsometric mapping, PPDL-D4-based inhomogeneously structured morphologies with a vertical dimension in the lower nm range could be mapped. In addition to the identification of these structures, the differentiation between a monolayer and bare water was possible. Second, the potential and limitations of this method were verified by applying it to more versatile Langmuir layers of telechelic poly[(rac-lactide)-co-glycolide]-diol (PLGA). All ellipsometric maps were converted into thickness maps by introduction of the refractive index that was derived from independent ellipsometric experiments, and the result was additionally evaluated in terms of the root mean square roughness, R-q. Thereby, a three-dimensional view into the layers was enabled and morphological inhomogeneity could be quantified. KW - ellipsometric mapping KW - Langmuir monolayer KW - polyester KW - root mean square roughness KW - spectroscopic ellipsometry Y1 - 2016 U6 - https://doi.org/10.3762/bjnano.7.107 SN - 2190-4286 VL - 7 SP - 1156 EP - 1165 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften CY - Frankfurt, Main ER -