@article{SunCernochVoelkeletal.2016, author = {Sun, Jing and Cernoch, Peter and V{\"o}lkel, Antje and Wei, Yuhan and Ruokolainen, Janne and Schlaad, Helmut}, title = {Aqueous Self-Assembly of a Protein-Mimetic Ampholytic Block Copolypeptide}, series = {Macromolecules : a publication of the American Chemical Society}, volume = {49}, journal = {Macromolecules : a publication of the American Chemical Society}, publisher = {American Chemical Society}, address = {Washington}, issn = {0024-9297}, doi = {10.1021/acs.macromol.6b00817}, pages = {5494 -- 5501}, year = {2016}, abstract = {This report describes the aggregation behavior of an ABC-type ampholytic block copolypeptide, poly(ethylene oxide)-block-poly(L-lysine)-block-poly(L-glutamate), in aqueous media in dependence of pH. Polypeptide secondary structures and self-assemblies are investigated by circular dichroism (CD), Fourier transform infrared (FT-IR) and NMR spectroscopy, zeta potential measurements, analytical ultracentrifugation (AUC), dynamic/static light scattering (DLS/SLS), and cryogenic transmission electron microscopy (cryoTEM). The polymer chains tend to form vesicles when the hydrophobic polypeptide helix is located at the chain end (acidic pH) and are existing as single chains when it is located in the center and flanked by the two hydrophilic segments (basic pH). Precipitation occurs in the intermediate pH range due to polyion complexation of the charged polypeptide segments.}, language = {en} } @article{YoukHofmannBadamdorjetal.2020, author = {Youk, Sol and Hofmann, Jan P. and Badamdorj, Bolortuya and Volkel, Antje and Antonietti, Markus and Oschatz, Martin}, title = {Controlling pore size and pore functionality in sp(2)-conjugated microporous materials by precursor chemistry and salt templating}, series = {Journal of materials chemistry : A, Materials for energy and sustainability}, volume = {8}, journal = {Journal of materials chemistry : A, Materials for energy and sustainability}, number = {41}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2050-7488}, doi = {10.1039/d0ta05856d}, pages = {21680 -- 21689}, year = {2020}, abstract = {The synthesis of sp(2)-conjugated, heteroatom-rich, "carbonaceous" materials from economically feasible raw materials and salt templates is reported. Low cost citrazinic acid (2,6-dihydroxy-4-pyridinecarboxylic acid) and melamine are used as components to form a microporous, amorphous framework, where edges of the covalent frameworks are tightly terminated with nitrogen and oxygen moieties. ZnCl2 as the porogen stabilizes structural microporosity as well as nitrogen and oxygen heteroatoms up to comparably high condensation temperatures of 750 and 950 degrees C. The specific surface area up to 1265 m(2) g(-1) is mainly caused by micropores and typical of heteroatom-rich carbon materials with such structural porosity. The unusually high heteroatom content reveals that the edges and pores of the covalent structures are tightly lined with heteroatoms, while C-C or C-H bonds are expected to have a minor contribution as compared to typical carbon materials without or with minor content of heteroatoms. Adsorption of water vapor and carbon dioxide are exemplarily chosen to illustrate the impact of this heteroatom functionalization under salt-templating conditions on the adsorption properties of the materials. 27.10 mmol g(-1) of H2O uptake (at p/p(0) = 0.9) can be achieved, which also proves the very hydrophilic character of the pore walls, while the maximum CO2 uptake (at 273 K) is 5.3 mmol g(-1). At the same time the CO2/N-2 adsorption selectivity at 273 K can reach values of up to 60. All these values are beyond those of ordinary high surface area carbons, also differ from those of N-doped carbons, and are much closer to those of organized framework species, such as C2N.}, language = {en} } @misc{MaiBoyeYuanetal.2015, author = {Mai, Tobias and Boye, Susanne and Yuan, Jiayin and V{\"o}lkel, Antje and Gr{\"a}wert, Marlies and G{\"u}nter, Christina and Lederer, Albena and Taubert, Andreas}, title = {Poly(ethylene oxide)-based block copolymers with very high molecular weights for biomimetic calcium phosphate mineralization}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-85299}, year = {2015}, abstract = {The present article is among the first reports on the effects of poly(ampholyte)s and poly(betaine)s on the biomimetic formation of calcium phosphate. We have synthesized a series of di- and triblock copolymers based on a non-ionic poly(ethylene oxide) block and several charged methacrylate monomers, 2-(trimethylammonium)ethyl methacrylate chloride, 2-((3-cyanopropyl)-dimethylammonium)ethyl methacrylate chloride, 3-sulfopropyl methacrylate potassium salt, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide. The resulting copolymers are either positively charged, ampholytic, or betaine block copolymers. All the polymers have very high molecular weights of over 106 g mol-1. All polymers are water-soluble and show a strong effect on the precipitation and dissolution of calcium phosphate. The strongest effects are observed with triblock copolymers based on a large poly(ethylene oxide) middle block (nominal Mn = 100 000 g mol-1). Surprisingly, the data show that there is a need for positive charges in the polymers to exert tight control over mineralization and dissolution, but that the exact position of the charge in the polymer is of minor importance for both calcium phosphate precipitation and dissolution.}, language = {en} } @article{CasseShkilnyyLindersetal.2012, author = {Casse, Olivier and Shkilnyy, Andriy and Linders, J{\"u}rgen and Mayer, Christian and H{\"a}ussinger, Daniel and V{\"o}lkel, Antje and Th{\"u}nemann, Andreas F. and Dimova, Rumiana and C{\"o}lfen, Helmut and Meier, Wolfgang P. and Schlaad, Helmut and Taubert, Andreas}, title = {Solution behavior of double-hydrophilic block copolymers in dilute aqueous solution}, series = {Macromolecules : a publication of the American Chemical Society}, volume = {45}, journal = {Macromolecules : a publication of the American Chemical Society}, number = {11}, publisher = {American Chemical Society}, address = {Washington}, issn = {0024-9297}, doi = {10.1021/ma300621g}, pages = {4772 -- 4777}, year = {2012}, abstract = {The self-assembly of double-hydrophilic poly(ethylene oxide)-poly(2-methyl-2-oxazoline) diblock copolymers in water has been studied. Isothermal titration calorimetry, small-angle X-ray scattering, and analytical ultracentrifugation suggest that only single polymer chains are present in solution. In contrast, light scattering and transmission electron microscopy detect aggregates with radii of ca. 100 nm. Pulsed field gradient NMR spectroscopy confirms the presence of aggregates, although only 2\% of the polymer chains undergo aggregation. Water uptake experiments indicate differences in the hydrophilicity of the two blocks, which is believed to be the origin of the unexpected aggregation behavior (in accordance with an earlier study by Ke et al. [Macromolecules 2009, 42, 5339-5344]). The data therefore suggest that even in double-hydrophilic block copolymers, differences in hydrophilicity are sufficient to drive polymer aggregation, a phenomenon that has largely been overlooked or ignored so far.}, language = {en} } @article{MaiBoyeYuanetal.2015, author = {Mai, Tobias and Boye, Susanne and Yuan, Jiayin and V{\"o}lkel, Antje and Gr{\"a}wert, Marlies and G{\"u}nter, Christina and Lederer, Albena and Taubert, Andreas}, title = {Poly(ethylene oxide)-based block copolymers with very high molecular weights for biomimetic calcium phosphate mineralization}, series = {RSC Advances : an international journal to further the chemical sciences}, journal = {RSC Advances : an international journal to further the chemical sciences}, number = {5}, publisher = {RSC Publishing}, address = {London}, issn = {2046-2069}, doi = {10.1039/c5ra20035k}, pages = {103494 -- 103505}, year = {2015}, abstract = {The present article is among the first reports on the effects of poly(ampholyte)s and poly(betaine)s on the biomimetic formation of calcium phosphate. We have synthesized a series of di- and triblock copolymers based on a non-ionic poly(ethylene oxide) block and several charged methacrylate monomers, 2-(trimethylammonium)ethyl methacrylate chloride, 2-((3-cyanopropyl)-dimethylammonium)ethyl methacrylate chloride, 3-sulfopropyl methacrylate potassium salt, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide. The resulting copolymers are either positively charged, ampholytic, or betaine block copolymers. All the polymers have very high molecular weights of over 106 g mol-1. All polymers are water-soluble and show a strong effect on the precipitation and dissolution of calcium phosphate. The strongest effects are observed with triblock copolymers based on a large poly(ethylene oxide) middle block (nominal Mn = 100 000 g mol-1). Surprisingly, the data show that there is a need for positive charges in the polymers to exert tight control over mineralization and dissolution, but that the exact position of the charge in the polymer is of minor importance for both calcium phosphate precipitation and dissolution.}, language = {en} }