@article{RazzaqBehlLendlein2018, author = {Razzaq, Muhammad Yasar and Behl, Marc and Lendlein, Andreas}, title = {Thermally-induced actuation of magnetic nanocomposites based on Oligo(ω-pentadecalactone) and covalently integrated magnetic nanoparticles}, series = {MRS advances: a journal of the Materials Research Society (MRS)}, volume = {3}, journal = {MRS advances: a journal of the Materials Research Society (MRS)}, number = {63}, publisher = {Cambridge University Press}, address = {New York}, issn = {2059-8521}, doi = {10.1557/adv.2018.613}, pages = {3783 -- 3791}, year = {2018}, abstract = {The incorporation of inorganic particles in a polymer matrix has been established as a method to adjust the mechanical performance of composite materials. We report on the influence of covalent integration of magnetic nanoparticles (MNP) on the actuation behavior and mechanical performance of hybrid nanocomposite (H-NC) based shape-memory polymer actuators (SMPA). The H-NC were synthesized by reacting two types of oligo(ω-pentadecalactone) (OPDL) based precursors with terminal hydroxy groups, a three arm OPDL (3 AOPDL, Mn = 6000 g mol•1-1 ) and an OPDL (Mn =3300 g • mol-1 ) coated magnetite nanoparticle ({\O} = 10 ± 2 nm), with a diisocyanate. These H-NC were compared to the homopolymer network regarding the actuation performance, contractual stress (σcontr) as well as thermal and mechanical properties. The melting range of the OPDL crystals (ΔTm,OPDL) was shifted in homo polymer networks from 36 ºC - 76 ºC to 41ºC - 81 °C for H-NC with 9 wt\% of MNP content. The actuators were explored by variation of separating temperature (Tsep), which splits the OPDL crystalline domain into actuating and geometry determining segments. Tsep was varied in the melting range of the nanocomposites and the actuation capability and contractual stress (σcontr) of the nanocomposite actuators could be adjusted. The reversible strain (εrev) was decreased from 11 ± 0.3\% for homo polymer network to 3.2±0.3\% for H-NC9 with 9 wt\% of MNP indicating a restraining effect of the MNP on chain mobility. The results show that the performance of H-NCs in terms of thermal and elastic properties can be tailored by MNP content, however for higher reversible actuation, lower MNP contents are preferable.}, language = {en} } @article{KruegerSchwarzeBaumannetal.2018, author = {Kr{\"u}ger, Stefanie and Schwarze, Michael and Baumann, Otto and G{\"u}nter, Christina and Bruns, Michael and K{\"u}bel, Christian and Szabo, Dorothee Vinga and Meinusch, Rafael and Bermudez, Veronica de Zea and Taubert, Andreas}, title = {Bombyx mori silk/titania/gold hybrid materials for photocatalytic water splitting}, series = {Beilstein journal of nanotechnology}, volume = {9}, journal = {Beilstein journal of nanotechnology}, publisher = {Beilstein-Institut zur F{\"o}rderung der Chemischen Wissenschaften}, address = {Frankfurt, Main}, issn = {2190-4286}, doi = {10.3762/bjnano.9.21}, pages = {187 -- 204}, year = {2018}, abstract = {The synthesis, structure, and photocatalytic water splitting performance of two new titania (TiO2)/gold(Au)/Bombyx mori silk hybrid materials are reported. All materials are monoliths with diameters of up to ca. 4.5 cm. The materials are macroscopically homogeneous and porous with surface areas between 170 and 210 m(2)/g. The diameter of the TiO2 nanoparticles (NPs) - mainly anatase with a minor fraction of brookite - and the Au NPs are on the order of 5 and 7-18 nm, respectively. Addition of poly(ethylene oxide) to the reaction mixture enables pore size tuning, thus providing access to different materials with different photocatalytic activities. Water splitting experiments using a sunlight simulator and a Xe lamp show that the new hybrid materials are effective water splitting catalysts and produce up to 30 mmol of hydrogen per 24 h. Overall the article demonstrates that the combination of a renewable and robust scaffold such as B. mori silk with a photoactive material provides a promising approach to new monolithic photocatalysts that can easily be recycled and show great potential for application in lightweight devices for green fuel production.}, language = {en} } @article{SchmidtSchultze2018, author = {Schmidt, Bernd and Schultze, Christiane}, title = {A one-pot synthesis of pyranocoumarins through microwave-promoted propargyl claisen rearrangement/wittig olefination}, series = {European journal of organic chemistry}, volume = {2018}, journal = {European journal of organic chemistry}, number = {2}, publisher = {Wiley-VCH Verl.}, address = {Weinheim}, issn = {1434-193X}, pages = {223 -- 227}, year = {2018}, abstract = {The reaction between propargyl ethers of hydroxybenzaldehydes and the ylide ethyl (triphenylphosphoranylidene)acetate was carried out under microwave irradiation to regioselectively afford angular pyranocoumarins. The chromene and coumarin heterocyclic scaffolds were simultaneously formed in the same synthetic step without changing the reaction conditions. The natural products seselin, braylin, and dipetalolactone were among the products synthesized by this method.}, language = {en} } @article{XiongWłodarczykGallandietal.2018, author = {Xiong, Tao and Włodarczyk, Radosław Stanisław and Gallandi, Lukas and K{\"o}rzd{\"o}rfer, Thomas and Saalfrank, Peter}, title = {Vibrationally resolved photoelectron spectra of lower diamondoids}, series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry}, volume = {148}, journal = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry}, number = {4}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0021-9606}, doi = {10.1063/1.5012131}, pages = {9}, year = {2018}, abstract = {Vibrationally resolved lowest-energy bands of the photoelectron spectra (PES) of adamantane, diamantane, and urotropine were simulated by a time-dependent correlation function approach within the harmonic approximation. Geometries and normal modes for neutral and cationic molecules were obtained from B3LYP hybrid density functional theory (DFT). It is shown that the simulated spectra reproduce the experimentally observed vibrational finestructure (or its absence) quite well. Origins of the finestructure are discussed and related to recurrences of autocorrelation functions and dominant vibrations. Remaining quantitative and qualitative errors of the DFT-derived PES spectra refer to (i) an overall redshift by ∼0.5 eV and (ii) the absence of satellites in the high-energy region of the spectra. The former error is shown to be due to the neglect of many-body corrections to ordinary Kohn-Sham methods, while the latter has been argued to be due to electron-nuclear couplings beyond the Born-Oppenheimer approximation [Gali et al., Nat. Commun. 7, 11327 (2016)].}, language = {en} } @article{HesseKlierSgarzietal.2018, author = {Hesse, Julia and Klier, Dennis Tobias and Sgarzi, Massimo and Nsubuga, Anne and Bauer, Christoph and Grenzer, Joerg and H{\"u}bner, Rene and Wislicenus, Marcus and Joshi, Tanmaya and Kumke, Michael Uwe and Stephan, Holger}, title = {Rapid Synthesis of Sub-10nm Hexagonal NaYF4-Based Upconverting Nanoparticles using Therminol((R))66}, series = {ChemistryOpen : including thesis treasury}, volume = {7}, journal = {ChemistryOpen : including thesis treasury}, number = {2}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2191-1363}, doi = {10.1002/open.201700186}, pages = {159 -- 168}, year = {2018}, abstract = {We report a simple one-pot method for the rapid preparation of sub-10nm pure hexagonal (-phase) NaYF4-based upconverting nanoparticles (UCNPs). Using Therminol((R))66 as a co-solvent, monodisperse UCNPs could be obtained in unusually short reaction times. By varying the reaction time and reaction temperature, it was possible to control precisely the particle size and crystalline phase of the UCNPs. The upconversion (UC) luminescence properties of the nanocrystals were tuned by varying the concentrations of the dopants (Nd3+ and Yb3+ sensitizer ions and Er3+ activator ions). The size and phase-purity of the as-synthesized core and core-shell nanocrystals were assessed by using complementary transmission electron microscopy, dynamic light scattering, X-ray diffraction, and small-angle X-ray scattering studies. In-depth photophysical evaluation of the UCNPs was pursued by using steady-state and time-resolved luminescence spectroscopy. An enhancement in the UC intensity was observed if the nanocrystals, doped with optimized concentrations of lanthanide sensitizer/activator ions, were further coated with an inert/active shell. This was attributed to the suppression of surface-related luminescence quenching effects.}, language = {en} } @article{YaoubaKochGuantaietal.2018, author = {Yaouba, Souaibou and Koch, Andreas and Guantai, Eric M. and Derese, Solomon and Irungu, Beatrice and Heydenreich, Matthias and Yenesew, Abiy}, title = {Alkenyl cyclohexanone derivatives from Lannea rivae and Lannea schweinfurthii}, series = {Phytochemistry letters / Phytochemical Society of Europe}, volume = {23}, journal = {Phytochemistry letters / Phytochemical Society of Europe}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1874-3900}, doi = {10.1016/j.phytol.2017.12.001}, pages = {141 -- 148}, year = {2018}, abstract = {Phytochemical investigation of the CH2Cl2/MeOH (1:1) extract of the roots of Lannea rivae (Chiov) Sacleux (Anacardiaceae) led to the isolation of a new alkenyl cyclohexenone derivative: (4R,6S)-4,6-dihydroxy-6-((Z)-nonadec-14′-en-1-yl)cyclohex-2-en-1-one (1), and a new alkenyl cyclohexanol derivative: (2S*,4R*,5S*)-2,4,5-trihydroxy-2-((Z)-nonadec-14′-en-1-yl)cyclohexanone (2) along with four known compounds, namely epicatechin gallate, taraxerol, taraxerone and β-sitosterol; while the stem bark afforded two known compounds, daucosterol and lupeol. Similar investigation of the roots of Lannea schweinfurthii (Engl.) Engl. led to the isolation of four known compounds: 3-((E)-nonadec-16′-enyl)phenol, 1-((E)-heptadec-14′-enyl)cyclohex-4-ene-1,3-diol, catechin, and 1-((E)-pentadec-12′-enyl)cyclohex-4-ene-1,3-diol. The structures of the isolated compounds were determined by NMR spectroscopy and mass spectrometry. The absolute configuration of compound 1 was established by quantum chemical ECD calculations. In an antibacterial activity assay using the microbroth kinetic method, compound 1 showed moderate activity against Escherichia coli while compound 2 exhibited moderate activity against Staphylococcus aureus. Compound 1 also showed moderate activity against E. coli using the disc diffusion method. The roots extract of L. rivae was notably cytotoxic against both the DU-145 prostate cancer cell line and the Vero mammalian cell line (CC50 = 5.24 and 5.20 μg/mL, respectively). Compound 1 was also strongly cytotoxic against the DU-145 cell line (CC50 = 0.55 μg/mL) but showed no observable cytotoxicity (CC50 > 100 μg/mL) against the Vero cell line. The roots extract of L. rivae and L. schweinfurthii, epicatechin gallate as well as compound 1 exhibited inhibition of carageenan-induced inflammation.}, language = {en} } @article{DaiMateGlebeetal.2018, author = {Dai, Xiaolin and Mate, Diana M. and Glebe, Ulrich and Garakani, Tayebeh Mirzaei and K{\"o}rner, Andrea and Schwaneberg, Ulrich and B{\"o}ker, Alexander}, title = {Sortase-mediated ligation of purely artificial building blocks}, series = {Polymers}, volume = {10}, journal = {Polymers}, number = {2}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym10020151}, pages = {13}, year = {2018}, abstract = {Sortase A (SrtA) from Staphylococcus aureus has been often used for ligating a protein with other natural or synthetic compounds in recent years. Here we show that SrtA-mediated ligation (SML) is universally applicable for the linkage of two purely artificial building blocks. Silica nanoparticles (NPs), poly(ethylene glycol) and poly(N-isopropyl acrylamide) are chosen as synthetic building blocks. As a proof of concept, NP-polymer, NP-NP, and polymer-polymer structures are formed by SrtA catalysis. Therefore, the building blocks are equipped with the recognition sequence needed for SrtA reaction-the conserved peptide LPETG-and a pentaglycine motif. The successful formation of the reaction products is shown by means of transmission electron microscopy (TEM), matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF MS), and dynamic light scattering (DLS). The sortase catalyzed linkage of artificial building blocks sets the stage for the development of a new approach to link synthetic structures in cases where their synthesis by established chemical methods is complicated.}, language = {en} } @article{SunOsenbergDongetal.2018, author = {Sun, Fu and Osenberg, Markus and Dong, Kang and Zhou, Dong and Hilger, Andre and Jafta, Charl J. and Risse, Sebastian and Lu, Yan and Markoetter, Henning and Manke, Ingo}, title = {Correlating Morphological Evolution of Li Electrodes with Degrading Electrochemical Performance of Li/LiCoO2 and Li/S Battery Systems}, series = {ACS energy letters / American Chemical Society}, volume = {3}, journal = {ACS energy letters / American Chemical Society}, number = {2}, publisher = {American Chemical Society}, address = {Washington}, issn = {2380-8195}, doi = {10.1021/acsenergylett.7b01254}, pages = {356 -- 365}, year = {2018}, abstract = {Efficient Li utilization is generally considered to be a prerequisite for developing next-generation energy storage systems (ESSs). However, uncontrolled growth of Li microstructures (LmSs) during electrochemical cycling has prevented its practical commercialization. Herein, we attempt to understand the correlation of morphological evolution of Li electrodes with degrading electrochemical performances of Li/LiCoO2 and Li/S systems by synchrotron X-ray phase contrast tomography technique. It was found that the continuous transformation of the initial dense Li bulk to a porous lithium interface (PL1) structure intimately correlates with the gradually degrading overall cell performance of these two systems. Additionally, the formation mechanism of the PLI and its correlation with previously reported inwardly growing LmS and the lithium-reacted region have been intensively discussed. The information that we gain herein is complementary to previous investigations and may provide general insights into understanding of degradation mechanisms of Li metal anodes and also provide highly needed guidelines for effective design of reliable next-generation Li metal-based ESSs.}, language = {en} } @article{SchmidtPetersenBraun2018, author = {Schmidt, Bernd and Petersen, Monib H. and Braun, Diana}, title = {Bidirectional Synthesis of 6-Acetoxy-5-hexadecanolide, the Mosquito Oviposition Pheromone of Culex quinquefasciatus, from a C-2-Symmetric Building Block Using Olefin Metathesis Reactions}, series = {The journal of organic chemistry}, volume = {83}, journal = {The journal of organic chemistry}, number = {3}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/acs.joc.7b02944}, pages = {1627 -- 1633}, year = {2018}, abstract = {(5R,6S)-6-Acetoxy-5-hexadecanolide (MOP) is the oviposition pheromone of the mosquito Cx. quinquefasciatus, a vector of pathogens causing a variety of tropical diseases. We describe and evaluate herein three syntheses of MOP starting from mannitol-derived (3R,4R)-hexa-1,5-diene-3,4-diol. This C-2-symmetric building block is elaborated through bidirectional olefin metathesis reactions into 6-epi-MOP, which was converted into MOP via Mitsunobu inversion. The shortest of the three routes makes use of two sequential cross-metathesis reactions and an assisted tandem catalytic olefin reduction, induced by an in situ conversion of a Ru-carbene to a Ru-hydride.}, language = {en} } @article{KleinpeterKoch2018, author = {Kleinpeter, Erich and Koch, Andreas}, title = {Paramagnetic ring current effects in anti-aromatic structures subject to substitution/annelation quantified by spatial magnetic properties (TSNMRS)}, series = {Tetrahedron}, volume = {74}, journal = {Tetrahedron}, number = {7}, publisher = {Elsevier}, address = {Oxford}, issn = {0040-4020}, doi = {10.1016/j.tet.2017.12.020}, pages = {700 -- 710}, year = {2018}, abstract = {The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of the typically anti-aromatic cyclopentadienyl cation, cyclobutadiene, pentalene, s-indacene and of substituted/annelated analogues of the latter structures have been calculated using the CIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values were employed to visualize and quantify the dia(para) magnetic ring current effects in the studied compounds. The interplay of dia(para)magnetic ring current effects due to substitution/annelation caused by heavy exo-cyclic n,pi-electron delocalization can be qualified.}, language = {en} } @article{ChenSongZhaoetal.2018, author = {Chen, Ye and Song, Qilei and Zhao, Junpeng and Gong, Xiangjun and Schlaad, Helmut and Zhang, Guangzhao}, title = {Betulin-Constituted multiblock amphiphiles for broad-spectrum protein resistance}, series = {ACS applied materials \& interfaces}, volume = {10}, journal = {ACS applied materials \& interfaces}, number = {7}, publisher = {American Chemical Society}, address = {Washington}, issn = {1944-8244}, doi = {10.1021/acsami.7b16255}, pages = {6593 -- 6600}, year = {2018}, abstract = {Multiblock-like amphiphilic polyurethanes constituted by poly(ethylene oxide) and biosourced betulin are designed for antifouling and synthesized by a convenient organocatalytic route comprising tandem chain-growth and step-growth polymerizations. The doping density of betulin (D-B) in the polymer chain structure is readily varied by a mixed-initiator strategy. The spin-coated polymer films exhibit unique nanophase separation and protein resistance behaviors. Higher D-B leads to enhanced surface hydrophobicity and, unexpectedly, improved protein resistance. It is found that the surface holds molecular-level heterogeneity when D-B is substantially high due to restricted phase separation; therefore, broad-spectrum protein resistance is achieved despite considerable surface hydrophobicity. As D-B decreases, the distance between adjacent betulin units increases so that hydrophobic nanodomains are formed, which provide enough landing areas for relatively small-sized proteins to adsorb on the surface.}, language = {en} } @article{HeinzeHanschenWiesnerReinholdetal.2018, author = {Heinze, Mandy and Hanschen, Franziska S. and Wiesner-Reinhold, Melanie and Baldermann, Susanne and Gr{\"a}fe, Jan and Schreiner, Monika and Neugart, Susanne}, title = {Effects of Developmental Stages and Reduced UVB and Low UV Conditions on Plant Secondary Metabolite Profiles in Pak Choi (Brassica rapa subsp chinensis)}, series = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, volume = {66}, journal = {Journal of agricultural and food chemistry : a publication of the American Chemical Society}, number = {7}, publisher = {American Chemical Society}, address = {Washington}, issn = {0021-8561}, doi = {10.1021/acs.jafc.7b03996}, pages = {1678 -- 1692}, year = {2018}, abstract = {Pak choi (Brassica rapa subsp. chinensis) is rich in secondary metabolites and contains numerous antioxidants, including flavonoids; hydroxycinnamic acids; carotenoids; chlorophylls; and glucosinolates, which can be hydrolyzed to epithionitriles, nitriles, or isothiocyanates. Here, we investigate the effect of reduced exposure to ultraviolet B (UVB) and UV (UVA and UVB) light at four different developmental stages of pak choi. We found that both the plant morphology and secondary metabolite profiles were affected by reduced exposure to UVB and UV, depending on the plant's developmental stage. In detail, mature 15- and 30-leaf plants had higher concentrations of flavonoids, hydroxycinnamic acids, carotenoids, and chlorophylls, whereas sprouts contained high concentrations of glucosinolates and their hydrolysis products. Dry weights and leaf areas increased as a result of reduced UVB and low UV. For the flavonoids and hydroxycinnamic acids in 30-leaf plants, less complex compounds were favored, for example, sinapic acid acylated kaempferol triglycoside instead of the corresponding tetraglycoside. Moreover, also in 30-leaf plants, zeaxanthin, a carotenoid linked to protection during photosynthesis, was increased under low UV conditions. Interestingly, most glucosinolates were not affected by reduced UVB and low UV conditions. However, this study underlines the importance of 4-(methylsulfinyl)butyl glucosinolate in response to UVA and UVB exposure. Further, reduced UVB and low UV conditions resulted in higher concentrations of glucosinolate-derived nitriles. In conclusion, exposure to low doses of UVB and UV from the early to late developmental stages did not result in overall lower concentrations of plant secondary metabolites.}, language = {en} } @article{RibarHuberSmialeketal.2018, author = {Ribar, Anita and Huber, Stefan E. and Smialek, Malgorzata A. and Tanzer, Katrin and Neustetter, Michael and Sch{\"u}rmann, Robin and Bald, Ilko and Denifl, Stephan}, title = {Hydroperoxyl radical and formic acid formation from common DNA stabilizers upon low energy electron attachment}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {20}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {8}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c7cp07697e}, pages = {5578 -- 5585}, year = {2018}, abstract = {2-Amino-2-(hydroxymethyl)-1,3-propanediol (TRIS) and ethylenediaminetetraacetic acid ( EDTA) are key components of biological buffers and are frequently used as DNA stabilizers in irradiation studies. Such surface or liquid phase studies are done with the aim to understand the fundamental mechanisms of DNA radiation damage and to improve cancer radiotherapy. When ionizing radiation is used, abundant secondary electrons are formed during the irradiation process, which are able to attach to the molecular compounds present on the surface. In the present study we experimentally investigate low energy electron attachment to TRIS and methyliminodiacetic acid ( MIDA), an analogue of EDTA, supported by quantum chemical calculations. The most prominent dissociation channel for TRIS is through hydroperoxyl radical formation, whereas the dissociation of MIDA results in the formation of formic and acetic acid. These compounds are well-known to cause DNA modifications, like strand breaks. The present results indicate that buffer compounds may not have an exclusive protecting effect on DNA as suggested previously.}, language = {en} } @article{SchneiderGuenterTaubert2018, author = {Schneider, Matthias and G{\"u}nter, Christina and Taubert, Andreas}, title = {Co-deposition of a hydrogel/calcium phosphate hybrid layer on 3D printed poly(lactic acid) scaffolds via dip coating}, series = {Polymers}, volume = {10}, journal = {Polymers}, number = {3}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym10030275}, pages = {19}, year = {2018}, abstract = {The article describes the surface modification of 3D printed poly(lactic acid) (PLA) scaffolds with calcium phosphate (CP)/gelatin and CP/chitosan hybrid coating layers. The presence of gelatin or chitosan significantly enhances CP co-deposition and adhesion of the mineral layer on the PLA scaffolds. The hydrogel/CP coating layers are fairly thick and the mineral is a mixture of brushite, octacalcium phosphate, and hydroxyapatite. Mineral formation is uniform throughout the printed architectures and all steps (printing, hydrogel deposition, and mineralization) are in principle amenable to automatization. Overall, the process reported here therefore has a high application potential for the controlled synthesis of biomimetic coatings on polymeric biomaterials.}, language = {en} } @article{FarhanRudolphNoecheletal.2018, author = {Farhan, Muhammad and Rudolph, Tobias and N{\"o}chel, Ulrich and Kratz, Karl and Lendlein, Andreas}, title = {Extractable Free Polymer Chains Enhance Actuation Performance of Crystallizable Poly(epsilon-caprolactone) Networks and Enable Self-Healing}, series = {Polymers}, volume = {10}, journal = {Polymers}, number = {3}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym10030255}, pages = {15}, year = {2018}, abstract = {Crosslinking of thermoplastics is a versatile method to create crystallizable polymer networks, which are of high interest for shape-memory actuators. Here, crosslinked poly(epsilon-caprolactone) thermosets (cPCLs) were prepared from linear starting material, whereby the amount of extractable polymer was varied. Fractions of 5-60 wt \% of non-crosslinked polymer chains, which freely interpenetrate the crosslinked network, were achieved leading to differences in the resulting phase of the bulk material. This can be described as "sponge-like" with open or closed compartments depending on the amount of interpenetrating polymer. The crosslinking density and the average network chain length remained in a similar range for all network structures, while the theoretical accessible volume for reptation of the free polymer content is affected. This feature could influence or introduce new functions into the material created by thermomechanical treatment. The effect of interpenetrating PCL in cPCLs on the reversible actuation was analyzed by cyclic, uniaxial tensile tests. Here, high reversible strains of up to Delta epsilon = 24\% showed the enhanced actuation performance of networks with a non-crosslinked PCL content of 30 wt \% resulting from the crystal formation in the phase of the non-crosslinked PCL and co-crystallization with network structures. Additional functionalities are reprogrammability and self-healing capabilities for networks with high contents of extractable polymer enabling reusability and providing durable actuator materials.}, language = {en} } @article{BehrendtSchlaad2018, author = {Behrendt, Felix Nicolas and Schlaad, Helmut}, title = {Entropy-Driven Ring-Opening Disulfide Metathesis Polymerization for the Synthesis of Functional Poly(disulfide)s}, series = {Macromolecular rapid communications}, volume = {39}, journal = {Macromolecular rapid communications}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201700735}, pages = {4}, year = {2018}, abstract = {Metal-free entropy-driven disulfide metathesis polymerization of unsaturated L-cystine based macrocycles produces high-molar-mass heterofunctional poly(disulfide)s, i.e., poly(ester-disulfide-alkene) and poly(amide-disulfide-alkene); M-w(app) = 44-60 kDa, (sic) > 1.7. The polymerization is fast and reaches equilibrium within 1-5 minutes (monomer conversion 70-90\%) in polar aprotic solvents such as N,N-dimethylacetamide, dimethylsulfoxide, or y-valerolactone. Thiol-terminated polymers are stable in bulk or when dissolved in weakly polar solvents, but rapidly depolymerize in dilute polar solution.}, language = {en} } @article{PilusoVukicevieNoecheletal.2018, author = {Piluso, Susanna and Vukicevie, Radovan and N{\"o}chel, Ulrich and Braune, Steffen and Lendlein, Andreas and Neffe, Axel T.}, title = {Sequential alkyne-azide cycloadditions for functionalized gelatin hydrogel formation}, series = {European polymer journal}, volume = {100}, journal = {European polymer journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0014-3057}, doi = {10.1016/j.eurpolymj.2018.01.017}, pages = {77 -- 85}, year = {2018}, abstract = {While click chemistry reactions for biopolymer network formation are attractive as the defined reactions may allow good control of the network formation and enable subsequent functionalization, tailoring of gelatin network properties over a wide range of mechanical properties has yet to be shown. Here, it is demonstrated that copper-catalyzed alkyne-azide cycloaddition of alkyne functionalized gelatin with diazides gave hydrogel networks with properties tailorable by the ratio of diazide to gelatin and diazide rigidity. 4,4′-diazido-2,2′-stilbenedisulfonic acid, which has been used as rigid crosslinker, yielded hydrogels with Young's moduli E of 50-390 kPa and swelling degrees Q of 150-250 vol.\%, while the more flexible 1,8-diazidooctane resulted in hydrogels with E = 125-280 kPa and Q = 225-470 vol.\%. Storage moduli could be varied by two orders of magnitude (G′ = 100-20,000 Pa). An indirect cytotoxicity test did not show cytotoxic properties. Even when employing 1:1 ratios of alkyne and azide moieties, the hydrogels were shown to contain both, unreacted alkyne groups on the gelatin backbone as well as dangling chains carrying azide groups as shown by reaction with functionalized fluorescein. The free groups, which can be tailored by the employed ratio of the reactants, are accessible for covalent attachment of drugs, as was demonstrated by functionalization with dexamethasone. The sequential network formation and functionalization with click chemistry allows access to multifunctional materials relevant for medical applications.}, language = {en} } @article{AravopoulouKyriakosMiasnikovaetal.2018, author = {Aravopoulou, Dionysia and Kyriakos, Konstantinos and Miasnikova, Anna and Laschewsky, Andre and Papadakis, Christine M. and Kyritsis, Apostolos}, title = {Comparative Investigation of the Thermoresponsive Behavior of Two Diblock Copolymers Comprising PNIPAM and PMDEGA Blocks}, series = {The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces \& biophysical chemistry}, volume = {122}, journal = {The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces \& biophysical chemistry}, number = {9}, publisher = {American Chemical Society}, address = {Washington}, issn = {1520-6106}, doi = {10.1021/acs.jpcb.7b09647}, pages = {2655 -- 2668}, year = {2018}, abstract = {The thermoresponsive behavior of two diblock copolymers PS-b-PNIPAM and PS-b-PMDEGA, which both comprise a hydrophobic polystyrene (PS) block but different thermoresponsive blocks, also differing in length, poly(N-isopropylacrylamide) (PNIPAM) and poly(methoxy diethylene glycol acrylate) (PMDEGA), respectively, was comparatively investigated in a wide temperature range. Concentrated aqueous solutions containing 25 wt \% polymer were studied by small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), and broadband dielectric spectroscopy (BDS). DSC measurements show that, during the demixing phase transition, the hydration number per oligo(ethylene glycol) side chain in the PS-b-PMDEGA solution decreases rather gradually, even up to 20 °C above the onset of the transition, i.e., the cloud point (CP). In contrast, the PS-b-PNIPAM solution exhibits an abrupt, stepwise dehydration behavior at its CP, indicated by the sharp, narrow endothermic peak. BDS measurements suggest that the organization of the expelled water during the phase transition and the subsequent evolution of the micellar aggregates are different for the two copolymers. In the PS-b-PMDEGA solution, the long-range charge transport process changes significantly at its CP and strong interfacial polarization processes appear, probably due to charge accumulation at the interfaces between the micellar aggregates and the aqueous medium. On the contrary, in the PS-b-PNIPAM solution, the phase transition has only a marginal effect on the long-range conduction process and is accompanied by a reduction in the high-frequency (1 MHz) dielectric permittivity, ε′. The latter effect is attributed to the reduced polarization strength of local chain modes due to an enhancement of intra- and interchain hydrogen bonds (HBs) in the polymer-rich phase during the water detaching process. Surprisingly, our BDS measurements indicate that prior to both the demixing and remixing processes the local chain mobility increases temporally. Our dielectric studies suggest that for PS-b-PNIPAM the water detaching process initiates a few degrees below CP and that the local chain mobility and intra- and/or interchain HBs of the PNIPAM blocks may control its thermoresponsive behavior. Dielectric "jump" experiments show that the kinetics of micellar aggregation in the PS-b-PMDEGA solution is slower than that in the PS-b-PNIPAM solution and is independent of the target temperature within the two-phase region. From the experimental point of view, it is shown that the dielectric susceptibility, especially, the dielectric permittivity, ε′, is a well-suited probe for monitoring both the reversible changes in the molecular dipolar bond polarizability and the long-range interfacial polarization at the phase transition.}, language = {en} } @article{SchulzeMakuchWagnerKounavesetal.2018, author = {Schulze-Makuch, Dirk and Wagner, Dirk and Kounaves, Samuel P. and Mangelsdorf, Kai and Devine, Kevin G. and de Vera, Jean-Pierre and Schmitt-Kopplin, Philippe and Grossart, Hans-Peter and Parro, Victor and Kaupenjohann, Martin and Galy, Albert and Schneider, Beate and Airo, Alessandro and Froesler, Jan and Davila, Alfonso F. and Arens, Felix L. and Caceres, Luis and Cornejo, Francisco Solis and Carrizo, Daniel and Dartnell, Lewis and DiRuggiero, Jocelyne and Flury, Markus and Ganzert, Lars and Gessner, Mark O. and Grathwohl, Peter and Guan, Lisa and Heinz, Jacob and Hess, Matthias and Keppler, Frank and Maus, Deborah and McKay, Christopher P. and Meckenstock, Rainer U. and Montgomery, Wren and Oberlin, Elizabeth A. and Probst, Alexander J. and Saenz, Johan S. and Sattler, Tobias and Schirmack, Janosch and Sephton, Mark A. and Schloter, Michael and Uhl, Jenny and Valenzuela, Bernardita and Vestergaard, Gisle and Woermer, Lars and Zamorano, Pedro}, title = {Transitory microbial habitat in the hyperarid Atacama Desert}, series = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {115}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {11}, publisher = {National Acad. of Sciences}, address = {Washington}, issn = {0027-8424}, doi = {10.1073/pnas.1714341115}, pages = {2670 -- 2675}, year = {2018}, language = {en} } @misc{MazzioThulasimaniRylletal.2018, author = {Mazzio, Katherine A. and Thulasimani, Monika Raja and Ryll, Britta and Kojda, Sandrino Danny and Habicht, Klaus and Raoux, Simone}, title = {Synthetic manipulation of hybrid thermoelectric materials}, series = {Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS}, volume = {255}, journal = {Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS}, publisher = {American Chemical Society}, address = {Washington}, issn = {0065-7727}, pages = {1}, year = {2018}, language = {en} }