Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-14184 Wissenschaftlicher Artikel Jelicic, Aleksandra; Garcia, Nuria; Beuermann, Sabine Influence of ionic liquid structure on the propagation kinetics of methyl methacrylate 2009 10.1021/ma900774e Institut für Chemie OPUS4-31474 Wissenschaftlicher Artikel Siegmann, Rebekka; Beuermann, Sabine Individual rate coefficients for 1H,1H,2H,2H-tridecafluorooctyl methacrylate radical polymerizations Kinetic data for radical polymerizations of 1H,1H,2H,2H-tridecafluorooctyl methacrylate (TDFOMA) in bulk is reported. Pulsed laser initiated polymerizations yield propagation rate coefficients, k(p), which are by a factor of 1.9 higher than methyl methacrylate k(p). The activation energy of TDFOMA k(p) is not significantly different from that of alkyl methacrylates. Chain-length averaged termination rate coefficients were estimated from chemically initiated polymerizations with in-line FT-NIR spectroscopic monitoring of monomer conversion. Up to 30% of monomer conversion TDFOMA termination rate coefficients are only slightly below MMA low conversion values. The result is suggested to be due to less interactions between the macroradicals compared to nonfluorinated systems. 2010 10.1021/Ma902653b Institut für Chemie OPUS4-31539 Wissenschaftlicher Artikel Vukicevic, Radovan; Hierzenberger, Peter; Hild, Sabine; Beuermann, Sabine Functionalization of carbon black nanoparticles with poly(vinylidene fluoride) The surface of carbon black (CB) nanoparticles was functionalized with poly(vinylidene fluoride) (PVDF) either by trapping of macroradicals or by cycloaddition. PVDF with two iodine end groups (I-PVDF-I) obtained from iodine transfer polymerization in supercritical CO2 was heated in the presence of CB and the C-I bond was cleaved resulting in a reaction between the macroradical and the CB surface. To allow for cycloaddition of PVDF to the CB surface for a number of polymers, the iodine end groups were replaced by azide end groups. In addition, microwave irradiation was applied to the functionalization. The influence of temperature, time, polymer concentration, and polymer molar mass on the functionalization reaction was examined. 2010 10.1002/Pola.24277 Institut für Chemie OPUS4-30081 Wissenschaftlicher Artikel Jelicic, Aleksandra; Garcia, Nuria; Löhmannsröben, Hans-Gerd; Beuermann, Sabine Prediction of the ionic liquid influence on propagation rate coefficients in methyl methacrylate radical polymerizations based on Kamlet-Taft solvatochromic parameters 2009 10.1021/ma9017907 Institut für Chemie OPUS4-31595 Wissenschaftlicher Artikel Breininger, Eugenia; Imran-ul-haq, Muhammad; Tuerk, Michael; Beuermann, Sabine Effect of polymer properties on poly(vinylidene fluoride) particles produced by rapid expansion of CO2 + polymer mixtures The generation of nanoscale primary poly(vinylidene fluoride) (PVDF) particles by rapid expansion of supercritical solutions (RESS) is reported. The experimental results show that RESS enables the formation of PVDF particles with median particle diameters ranging from 56 to 226 nm and that the size of PVDF particles can be influenced by polymer properties. The particle size can be decreased either by increasing molar mass, in case of identical polymer end groups, or by increasing the degree of crystallinity, in case of similar molar mass and different end groups. 2009 10.1016/j.supflu.2008.09.016 Institut für Chemie OPUS4-31581 Wissenschaftlicher Artikel Beuermann, Sabine Solvent influence on propagation kinetics in radical polymerizations studied by pulsed laser initiated polymerizations The influence of the reaction medium (organic solvents, water, ionic liquids, supercritical CO2) on the propagation rate in radical polymerizations has very different causes, e.g., hindered rotational modes, hydrogen bonding or electron pair donor/acceptor interactions. Depending on the origin of the solvent influence propagation rate coefficients, k(P), may be enhanced by up to an order of magnitude associated with changes in the pre-exponential or the activation energy of k(P). In contrast, non-specific interactions, size and steric effects lead to rather small changes in the vicinity of the radical chain end and are reflected by modest variations in k(P). 2009 10.1002/marc.200900131 Institut für Chemie OPUS4-30846 Wissenschaftlicher Artikel Beuermann, Sabine Solvent influence on propagation kinetics in radical polymerizations studied by pulsed laser initiated polymerizations The influence of the reaction medium (organic solvents, water, ionic liquids, supercritical CO2) on the propagation rate in radical polymerizations has very different causes, e.g., hindered rotational modes, hydrogen bonding, or electron pair donor / acceptor interactions. Depending on the origin of the solvent influence propagation rate coefficients, kp, may be enhanced by up to an order of magnitude associated with changes in the pre-exponential or the activation energy of kp. Contrary, non-specific interactions, size and steric effects lead to rather small changes in the vicinity of the radical chain end and are reflected by modest variations in kp. 2009 Institut für Chemie OPUS4-36798 Wissenschaftlicher Artikel Jelicic, Aleksandra; Yasin, Muttaqin; Beuermann, Sabine Toward the description and prediction of solvent induced variations in Methacrylate Propagation Rate Coefficients on the basis of Solvatochromic Parameters Benzyl methacrylate (BzMA) propagation rate coefficients, k(p), were determined in ionic liquids and common organic solvents via pulsed-laser polymerizations with subsequent polymer analysis by size-exclusion chromatography (PLP-SEC). The aim of the work is to gain a deeper understanding of the solvent influence on k(p) and to develop a general correlation between solvent-induced variations in k(p) and solvent properties. Applying a linear solvation energy relationship (LSER), which correlates k(p) to solvent solvatochromic parameters, suggests that dipolarity/polarizability determines the solvent influence on k(p). To compare the solvent influence on BzMA k(p) with data for methyl methacrylate, hydroxypropyl methacrylate, and 2-ethoxyethyl methacrylate normalized k(p) data were treated by a single LSER, providing a universal treatment of the solvent influence on the propagation kinetics of the four monomers. Further, the predictive capabilities of this universal correlation were tested with additional monomers from the methacrylate family. Malden Wiley-Blackwell 2011 11 Macromolecular reaction engineering 5 5-6 232 242 10.1002/mren.201000058 Institut für Chemie OPUS4-36809 Wissenschaftlicher Artikel Cockburn, Robert A.; Siegmann, Rebekka; Payne, Kevin A.; Beuermann, Sabine; McKenna, Timothy F. L.; Hutchinson, Robin A. Free Radical Copolymerization Kinetics of gamma-Methyl-alpha-methylene-gamma-butyrolactone (MeMBL) The propagation kinetics and copolymerization behavior of the biorenewable monomer gamma-methyl-alpha-methylene-gamma-butyrolactone (MeMBL) are studied using the Pulsed laser polymerization (PLP)/size exclusion chromatography (SEC) technique. The propagation rate coefficent for MeMBL is 15% higher than that of its structural analogue, methyl methacrylate (MMA), with a similar activation energy of 21.8 kJ . mol(-1). When compared to MMA, MeMBL is preferentially incorporated into copolymers when reacted with styrene (ST), MMA, and n-butyl acrylate (BA); the monomer reactivity ratios fit from bulk MeMBL/ST, MeMBL/MMA, and MeMBL/BA copolymerizations are r(MeMBL) = 0.80 +/- 0.04 and r(ST) = 0.34 +/- 0.04, r(MeMBL), = 3.0 +/- 0.3 and r(MMA) = 0.33 +/- 0.01, and r(MeMBL) = 7.0 +/- 2.0 and r(BA) = 0.16 +/- 0.03, respectively. In all cases, no significant variation with temperature was found between 50 and 90 degrees C. The implicit penultimate unit effect (IPUE) model was found to adequately fit the composition-averaged copolymerization propagation rate coefficient, k(p,cop), for the three systems. Washington American Chemical Society 2011 8 Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences 12 6 2319 2326 10.1021/bm200400s Institut für Chemie OPUS4-35757 Wissenschaftlicher Artikel Siegmann, Rebekka; Möller, Eleonore; Beuermann, Sabine Propagation rate coefficients for homogeneous phase VDF-HFP copolymerization in supercritical CO2 For the first time, propagation rate coefficients, kp,COPO, for the copolymerizations of vinylidene fluoride and hexafluoropropene have been determined. The kinetic data was determined via pulsed-laser polymerization in conjunction with polymer analysis via size-exclusion chromatography, the PLP-SEC technique. The experiments were carried out in homogeneous phase with supercritical CO2 as solvent for temperatures ranging from 45 to 90 degrees C. Absolute polymer molecular weights were calculated on the basis of experimentally determined MarkHouwink constants. The Arrhenius parameters of kp,COPO vary significantly compared with ethene, which is explained by the high electronegativity of fluorine and less intra- and intermolecular interactions between the partially fluorinated macroradicals. Weinheim Wiley-VCH 2012 6 Macromolecular rapid communications 33 14 1208 1213 10.1002/marc.201200115 Institut für Chemie OPUS4-36293 Wissenschaftlicher Artikel Vukicevic, Radovan; Vukovic, Ivana; Stoyanov, Hristiyan; Korwitz, Andreas; Pospiech, Doris; Kofod, Guggi; Loos, Katja; ten Brinke, Gerrit; Beuermann, Sabine Poly(vinylidene fluoride)-functionalized single-walled carbon nanotubes for the preparation of composites with improved conductivity The surface of single-walled carbon nanotubes (SWCNTs) was functionalized with azide-terminated poly(vinylidene fluoride) (PVDF). Functionalization was confirmed by dispersibility, Raman spectroscopy, and thermogravimetric analyses. Raman spectra show disordering of the SWCNTs, thus, strongly suggesting that PVDF was covalently attached to SWCNTs. Functionalized SWCNTs were mixed with commercially available PVDF in a twin-screw extruder and thin films were obtained by melt-pressing. Films containing 0.5 and 1 wt% PVDF-functionalized SWCNTs exhibited significantly improved electrical conductivity compared to PVDF films containing pristine SWCNTs. Cambridge Royal Society of Chemistry 2012 5 Polymer Chemistry 3 8 2261 2265 10.1039/c2py20166f Institut für Chemie OPUS4-36898 Wissenschaftlicher Artikel Vukicevic, Radovan; Beuermann, Sabine Fullerenes decorated with poly(vinylidene fluoride) Fullerenes decorated with poly(vinylidene fluoride) (PVDF) were synthesized in a three-step procedure: Iodine transfer polymerization of vinylidene fluoride with C(6)F(12)I(2) as the chain transfer agent was carried out in supercritical carbon dioxide to synthesize iodine-terminated PVDF, which was subsequently transformed to azide-terminated polymer. Finally, azide-terminated PVDF chains were attached to a fullerene core under microwave irradiation at 160 degrees C in 1.5 h. The materials were characterized by NMR, FT-IR, UV/vis, GPC, elemental analysis, and DSC. On average, 4-5 PVDF chains are attached to one C(60) moiety. FT-IR spectra and DSC measurements indicate that the polymer end groups strongly affect the crystallinity of the material. For PVDF with azide end groups and PVDF attached to fullerenes the fraction of the beta polymorph is dominant while alpha polymorphs are almost absent. Washington American Chemical Society 2011 7 Macromolecules : a publication of the American Chemical Society 44 8 2597 2603 10.1021/ma102754c Institut für Chemie OPUS4-36673 Konferenzveröffentlichung Vukicevic, Radovan; Schreiber, Ulrike; Beuermann, Sabine Azide-terminated poly(vinylidene fluoride) as building block for nanocomposite materials and block copolymers Washington American Chemical Society 2011 1 Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS 242 16 Institut für Chemie OPUS4-36672 Konferenzveröffentlichung Schreiber, Ulrike; Vukicevic, Radovan; Beuermann, Sabine Block copolymers of poly(vinylidene fluoride) obtained via 1,3 dipolar cycloaddition Washington American Chemical Society 2011 1 Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS 242 Institut für Chemie OPUS4-36194 Wissenschaftlicher Artikel Barth, Johannes; Siegmann, Rebekka; Beuermann, Sabine; Russell, Gregory T.; Buback, Michael Investigations into chain-length-dependent termination in bulk radical polymerization of 1H, 1H, 2H, 2H-Tridecafluorooctyl methacrylate The SP-PLP-EPR technique is used to carry out a detailed investigation of the radical termination kinetics of 1H, 1H, 2H, 2H-tridecafluorooctyl methacrylate (TDFOMA) in bulk at relatively low conversion. Composite-model behavior for chain-length-dependent termination rate coefficients, kti,i, is observed. It is found that for TDFOMA, ic approximate to 60 independent of temperature, and as approximate to 0.65 and al approximate to 0.2 at 80 degrees C and above. However, at lower temperatures the situation is strikingly different, with the significantly higher average values of as = 0.89 +/- 0.15 and al = 0.32 +/- 0.10 being obtained at 50 degrees C and below. This makes TDFOMA the first monomer to be found that exhibits clearly different exponent values, as and al, at lower and higher temperature, and that has both a high as, like an acrylate, and a high ic, like a methacrylate. Malden Wiley-Blackwell 2012 10 Macromolecular chemistry and physics 213 1 19 28 10.1002/macp.201100479 Institut für Chemie OPUS4-36385 Wissenschaftlicher Artikel Vukicevic, Radovan; Schwadtke, Ulrike; Schmuecker, Simon; Schaefer, Philipp; Kuckling, Dirk; Beuermann, Sabine Alkyne-azide coupling of tailored poly(vinylidene fluoride) and polystyrene for the synthesis of block copolymers The synthesis of block copolymers consisting of poly(vinylidene fluoride) (PVDF) and polystyrene (PS) is reported. Firstly, a propargyl-functionalized alkoxyamine initiator (PgOTIPNO) was prepared and subsequently used for the preparation of a propargyl-terminated PS homopolymer of different chain lengths with low dispersities via nitroxide-mediated radical polymerization. A tailored PVDF homopolymer with iodine end groups originating from iodine transfer polymerization was transformed to PVDF with azide end group. Then, alkyne-terminated PS with different molecular weights and azide-terminated PVDF were joined together via copper-catalyzed alkyne-azide coupling. The block copolymers were characterized using H-1-NMR, F-19-NMR, IR, SEC, and DSC. Cambridge Royal Society of Chemistry 2012 6 Polymer Chemistry 3 2 409 414 10.1039/c1py00427a Institut für Chemie OPUS4-37080 Wissenschaftlicher Artikel Möller, Eleonore; Beuermann, Sabine Homogeneous phase copolymerizations of vinylidene fluoride and hexafluoropropene in supercritical carbon dioxide Copolymerizations of vinylidene fluoride (VDF) and hexafluoropropene (HFP) were carried out in homogeneous phase with supercritical carbon dioxide up to complete VDF conversion using conventional peroxide initiators. The HFP monomer feed ratios, f(HFP), were varied between 0.65 and 0.20. Depending on f(HFP) amorphous or semi-crystalline copolymers were obtained. f(HFP) also determines the minimum pressure required to allow for homogeneous phase reactions. For example, HFP-rich copolymerizations in 70 wt.-% CO(2) at 100 degrees C require a pressure of around 500 bar. Further, bulk copolymerizations in homogenous phase were feasible for f(HFP) 0.65 at 900 bar up to complete VDF conversion. Copolymerizations in the presence of perfluorinated hexyl iodide carried out at 75 degrees C gave access to low dispersity polymers. Due to homogeneous phase conditions the use of any surfactants or fluorinated cosolvent is avoided. Weinheim Wiley-VCH 2011 14 Macromolecular reaction engineering 5 1 8 21 10.1002/mren.201000031 Institut für Chemie OPUS4-37071 Wissenschaftlicher Artikel Schreiber, Ulrike; Hosemann, Benjamin; Beuermann, Sabine 1H,1H,2H,2H-Perfluorodecyl-Acrylate-Containing block copolymers from ARGET ATRP Block copolymers of 1H,1H,2H,2H-perfluorodecyl acrylate (AC8) were obtained from ARGET ATRP. To obtain block copolymers of low dispersity the PAC8 block was synthesized in anisole with a CuBr(2)/PMDETA catalyst in the presence of tin(II) 2-ethylhexanoate as a reducing agent. The PAC8 block was subsequently used as macroinitiator for copolymerization with butyl and tert-butyl acrylate carried out in scCO(2). To achieve catalyst solubility in CO(2) two fluorinated ligands were employed. The formation of block copolymers was confirmed by size exclusion chromatography and DSC. Weinheim Wiley-VCH 2011 12 Macromolecular chemistry and physics 212 2 168 179 10.1002/macp.201000307 Institut für Chemie OPUS4-38235 Wissenschaftlicher Artikel Schmidt, Christian; Behl, Marc; Lendlein, Andreas; Beuermann, Sabine Synthesis of high molecular weight polyglycolide in supercritical carbon dioxide Polyglycolide (PGA) is a biodegradable polymer with multiple applications in the medical sector. Here the synthesis of high molecular weight polyglycolide by ring-opening polymerization of diglycolide is reported. For the first time stabilizer free supercritical carbon dioxide (scCO(2)) was used as a reaction medium. scCO(2) allowed for a reduction in reaction temperature compared to conventional processes. Together with the lowering of monomer concentration and consequently reduced heat generation compared to bulk reactions thermal decomposition of the product occurring already during polymerization is strongly reduced. The reaction temperatures and pressures were varied between 120 and 150 degrees C and 145 to 1400 bar. Tin(II) ethyl hexanoate and 1-dodecanol were used as catalyst and initiator, respectively. The highest number average molecular weight of 31 200 g mol(-1) was obtained in 5 hours from polymerization at 120 degrees C and 530 bar. In all cases the products were obtained as a dry white powder. Remarkably, independent of molecular weight the melting temperatures were always at (219 +/- 2)degrees C. Cambridge Royal Society of Chemistry 2014 7 RSC Advances 4 66 35099 35105 10.1039/c4ra06815g Institut für Chemie OPUS4-11956 Wissenschaftlicher Artikel Xie, Zai-Lai; Jelicic, Aleksandra; Wang, Feipeng; Rabu, Pierre; Friedrich, Alwin; Beuermann, Sabine; Taubert, Andreas Transparent, flexible, and paramagnetic ionogels based on PMMA and the iron-based ionic liquid 1-butyl-3- methylimidazolium tetrachloroferrate(III) [Bmim][FeCl4] The iron-containing ionic liquid (IL) 1-butyl-3-methylimidazolium tetrachloroferrate(III) [Bmim][FeCl4] has been used as a building block in the synthesis of transparent, ion-conducting, and paramagnetic ionogels. UV/Vis spectroscopy shows that the coordination around the Fe(III) ion does slightly change upon incorporation of the IL into PMMA. The thermal stability of the PMMA increases significantly with IL incorporation. In particular, the onset weight loss observed at ca. 265 degrees C for pure PMMA is completely suppressed. The ionic conductivity shows a strong temperature dependence and increases with increasing IL weight fractions. The magnetic properties are similar to those reported for the pure IL and are not affected by the incorporation into the PMMA matrix. The resulting ionogel is thus an interesting prototype for soft, flexible, and transparent materials combining the mechanical properties of the matrix with the functionality of the metal-containing IL, such as magnetism. 2010 10.1039/C0jm01733g Institut für Chemie