@article{BehrendtHessLehmannetal.2019, author = {Behrendt, Felix Nicolas and Hess, Andreas and Lehmann, Max and Schmidt, Bernd and Schlaad, Helmut}, title = {Polymerization of cystine-derived monomers}, series = {Polymer Chemistry}, volume = {10}, journal = {Polymer Chemistry}, number = {13}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/c9py00118b}, pages = {1636 -- 1641}, year = {2019}, abstract = {Cystine was used as a platform chemical to prepare cyclic and acyclic monomers for entropy-driven ringopening polymerization (ED-ROMP) via olefin or disulfide metathesis and for step-growth polymerization. The olefin ED-ROMP of an olefin/disulfide containing 16-atom macrocycle using the 3rd generation Grubbs catalyst was examined in greater detail. Kinetic studies revealed that the catalyst turned inactive during the polymerization, which limited the achievable (apparent) polymer molar mass to similar to 70 kg mol(-1). Such limitation could be overcome with the disulfide ED-ROMP of the same macrocycle to yield polymers with molar masses of up to 180 kg mol(-1). The step-growth polymerizations of acyclic diene and dithiol monomers via olefin metathesis or oxidation were far less effective and yielded just low molar mass polymers or oligomers; photopolymerization of a thiol-ene monomer produced a polyester with a molar mass of 35 kg mol(-1).}, language = {en} } @article{DasElTawargyKhechineetal.2019, author = {Das, Abhijna and El-Tawargy, Ahmed S. and Khechine, Emna and Noack, Sebastian and Schlaad, Helmut and Reiter, G{\"u}nter and Reiter, Renate}, title = {Controlling Nucleation in Quasi-Two-Dimensional Langmuir Poly(L-lactide) Films through Variation of the Rate of Compression}, series = {Langmuir}, volume = {35}, journal = {Langmuir}, number = {18}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.9b00619}, pages = {6129 -- 6136}, year = {2019}, abstract = {We studied morphological changes in a quasi-two-dimensional Langmuir film of low molar mass poly(L-lactide) upon increasing the surface density, starting from randomly distributed molecules to a homogeneous monolayer of closely packed molecules, followed by nucleation and growth of mesoscopic, three-dimensional clusters from an overcompressed monolayer. The corresponding nucleation density of mesoscopic clusters within the monolayer can be tailored through variation of the rate of compression. For a given surface density and temperature, the nucleation probability was found to increase linearly with the rate of compression, allowing to adjust the density of mesoscopic clusters over nearly 2 orders magnitude.}, language = {en} } @article{DebsharmaBehrendtLaschewskyetal.2019, author = {Debsharma, Tapas and Behrendt, Felix Nicolas and Laschewsky, Andre and Schlaad, Helmut}, title = {Ring-opening metathesis polymerization of biomass-derived levoglucosenol}, series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker}, volume = {58}, journal = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker}, number = {20}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1433-7851}, doi = {10.1002/anie.201814501}, pages = {6718 -- 6721}, year = {2019}, abstract = {The readily available cellulose-derived bicyclic compound levoglucosenol was polymerized through ring-opening metathesis polymerization (ROMP) to yield polylevoglucosenol as a novel type of biomass-derived thermoplastic polyacetal, which, unlike polysaccharides, contains cyclic as well as linear segments in its main chain. High-molar-mass polyacetals with apparent weight-average molar masses of up to 100kgmol(-1) and dispersities of approximately 2 were produced despite the non-living/controlled character of the polymerization due to irreversible deactivation or termination of the catalyst/active chain ends. The resulting highly functionalized polyacetals are glassy in bulk with a glass transition temperature of around 100 degrees C. In analogy to polysaccharides, polylevoglucosenol degrades slowly in an acidic environment.}, language = {en} } @article{JainWheelerEssetal.2019, author = {Jain, Varun and Wheeler, Joshua J. and Ess, Daniel H. and Noack, Sebastian and Vacogne, Charlotte D. and Schlaad, Helmut and Bahr, Stephan and Dietrich, Paul and Meyer, Michael and Thissen, Andreas and Linford, Matthew R.}, title = {Poly(gamma-benzyl l-glutamate), by near-ambient pressure XPS}, series = {Surface science spectra : SSS : an international journal \& database devoted to archiving spectra from surfaces \& interfaces}, volume = {26}, journal = {Surface science spectra : SSS : an international journal \& database devoted to archiving spectra from surfaces \& interfaces}, number = {2}, publisher = {American Institute of Physics}, address = {Melville}, issn = {1055-5269}, doi = {10.1116/1.5109121}, pages = {10}, year = {2019}, abstract = {Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i. e., at greater than 2500 Pa. In this study, poly(.- benzyl L- glutamate) (PBLG) with a molar mass of 11.3 kg/mol was analyzed by NAP-XPS; here, we show the survey, C 1s, N 1s, and O 1s narrow scans of PBLG. The C 1s peak envelope was fitted in three different ways, to five, six, or seven synthetic peaks. In each fit, there was also a shake-up signal. The O 1s narrow scan was well fit with three peaks: CZO and CvO in a 1:2 ratio from the polymer, and a higher energy signal from water vapor. Hartree-Fock orbital energies of a model monomer served as a guide to an additional fit of the C 1s envelope.}, language = {en} } @article{LuedeckeWeidnerSchlaad2019, author = {L{\"u}decke, Nils and Weidner, Steffen M. and Schlaad, Helmut}, title = {Poly(2-oxazoline)s Based on Phenolic Acids}, series = {Macromolecular rapid communications}, volume = {41}, journal = {Macromolecular rapid communications}, number = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201900404}, pages = {5}, year = {2019}, abstract = {A series of phenolic-acid-based 2-oxazoline monomers with methoxy-substituted phenyl and cinnamyl side chains is synthesized and polymerized in a microwave reactor at 140 °C using methyl tosylate as the initiator. The obtained poly(2-oxazoline)s are characterized by NMR spectroscopy, MALDI-TOF mass spectrometry, and size-exclusion chromatography (SEC). Kinetic studies reveal that the microwave-assisted polymerization is fast and completed within less than ≈10 min for low monomer-to-initiator ratios of ≤25. Polymers with number-average molar masses of up to 6500 g mol-1 and low dispersity (1.2-1.3) are produced. The aryl methyl ethers are successfully cleaved with aluminum triiodide/N,N′-diisopropylcarbodiimide to give a poly(2-oxazoline) with pendent catechol groups.}, language = {en} } @article{PatelNoackVacogneetal.2019, author = {Patel, Dhananjay I. and Noack, Sebastian and Vacogne, Charlotte D. and Schlaad, Helmut and Bahr, Stephan and Dietrich, Paul and Meyer, Michael and Thissen, Andreas and Linford, Matthew R.}, title = {Poly(L-lactic acid), by near-ambient pressure XPS}, series = {Surface Science Spectra}, volume = {26}, journal = {Surface Science Spectra}, number = {2}, publisher = {American Institute of Physics}, address = {Melville}, issn = {1055-5269}, doi = {10.1116/1.5110309}, pages = {8}, year = {2019}, abstract = {Near ambient pressure - x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at 2500Pa or higher. With NAP-XPS, one can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission we show C 1s, O 1s, and survey NAP-XPS spectra from poly(L-lactic acid). The C 1s and O 1s envelopes were fit with three and two Gaussian-Lorentzian sum functions, respectively. Water vapor (800Pa) was used as the residual gas for charge compensation, which was confirmed by the sharp peak at 535.0 eV in the O 1s narrow scan. The uniqueness plot corresponding to the C 1s fit shows that the fit parameters had statistical significance. C 1s and O 1s spectra of PLLA damaged by exposure to x-rays for ca. 1 hour are also included. Published by the AVS.}, language = {en} } @misc{RajuLiebigHessetal.2019, author = {Raju, Rajarshi Roy and Liebig, Ferenc and Hess, Andreas and Schlaad, Helmut and Koetz, Joachim}, title = {Temperature-triggered reversible breakdown of polymer-stabilized olive}, series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, number = {751}, issn = {1866-8372}, doi = {10.25932/publishup-43646}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436461}, pages = {19271 -- 19277}, year = {2019}, abstract = {A one-step moderate energy vibrational emulsification method was successfully employed to produce thermo-responsive olive/silicone-based Janus emulsions stabilized by poly(N,N-diethylacrylamide) carrying 0.7 mol\% oleoyl side chains. Completely engulfed emulsion droplets remained stable at room temperature and could be destabilized on demand upon heating to the transition temperature of the polymeric stabilizer. Time-dependent light micrographs demonstrate the temperature-induced breakdown of the Janus droplets, which opens new aspects of application, for instance in biocatalysis.}, language = {en} } @article{RajuLiebigHessetal.2019, author = {Raju, Rajarshi Roy and Liebig, Ferenc and Hess, Andreas and Schlaad, Helmut and Koetz, Joachim}, title = {Temperature-triggered reversible breakdown of polymer-stabilized olive}, series = {RSC Advances}, volume = {9}, journal = {RSC Advances}, number = {35}, publisher = {RSC Publishing}, address = {London}, issn = {2046-2069}, doi = {10.1039/c9ra03463c}, pages = {19271 -- 19277}, year = {2019}, abstract = {A one-step moderate energy vibrational emulsification method was successfully employed to produce thermo-responsive olive/silicone-based Janus emulsions stabilized by poly(N,N-diethylacrylamide) carrying 0.7 mol\% oleoyl side chains. Completely engulfed emulsion droplets remained stable at room temperature and could be destabilized on demand upon heating to the transition temperature of the polymeric stabilizer. Time-dependent light micrographs demonstrate the temperature-induced breakdown of the Janus droplets, which opens new aspects of application, for instance in biocatalysis.}, language = {en} } @inproceedings{SchlaadLuedecke2019, author = {Schlaad, Helmut and Luedecke, Nils}, title = {Bio-sourced chelating poly(2-oxazoline)s}, series = {Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS}, volume = {257}, booktitle = {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 = {2019}, language = {en} }