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Volker Abetz - One of the best experts on this subject based on the ideXlab platform.
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isoporous membranes from novel polystyrene b poly 4 vinylpyridine b poly solketal methacrylate ps b p4vp b psma triblock terpolymers and their post modification
Polymers, 2019Co-Authors: Sarah Saleem, Volkan Filiz, Clarissa Abetz, Volker Abetz, Sofia RangouAbstract:In this paper, the formation of nanostructured triblock terpolymer polystyrene-b-poly(4-vinylpyridine)-b-poly(solketal methacrylate) (PS-b-P4VP-b-PSMA), polystyrene-b-poly(4-vinylpyridine)-b-poly(glyceryl methacrylate) (PS-b-P4VP-b-PGMA) membranes via block copolymer self-assembly followed by non-solvent-induced phase separation (SNIPS) is demonstrated. An increase in the hydrophilicity was observed after treatment of non-charged isoporous membranes from PS-b-P4VP-b-PSMA, through acidic hydrolysis of the hydrophobic poly(solketal methacrylate) PSMA block into a hydrophilic poly(glyceryl methacrylate) PGMA block, which contains two neighbored hydroxyl (–OH) groups per repeating unit. For the first time, PS-b-P4VP-b-PSMA triblock terpolymers with varying compositions were successfully synthesized by sequential living anionic polymerization. Composite membranes of PS-b-P4VP-b-PSMA and PS-b-P4VP-b-PGMA triblock terpolymers with ordered hexagonally packed cylindrical pores were developed. The morphology of the membranes was studied with scanning electron microscopy (SEM) and atomic force microscopy (AFM). PS-b-P4VP-b-PSMA triblock terpolymer membranes were further treated with acid (1 M HCl) to get polystyrene-b-poly(4-vinylpyridine)-b-poly(glyceryl methacrylate) (PS-b-P4VP-b-PGMA). Notably, the pristine porous membrane structure could be maintained even after acidic hydrolysis. It was found that membranes containing hydroxyl groups (PS-b-P4VP-b-PGMA) show a stable and higher water permeance than membranes without hydroxyl groups (PS-b-P4VP-b-PSMA), what is due to the increase in hydrophilicity. The membrane properties were analyzed further by contact angle, protein retention, and adsorption measurements.
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Postfunctionalization of Nanoporous Block Copolymer Membranes via Click Reaction on Polydopamine for Liquid Phase Separation
2018Co-Authors: Christian Höhme, Volkan Filiz, Clarissa Abetz, Prokopios Georgopanos, Nico Scharnagl, Volker AbetzAbstract:In this work, an azido-modified dopamine derivative was synthesized and subsequently used to postfunctionalize the surface of nanoporous poly(styrene)-block-poly(4-vinylpyridine) diblock copolymer membranes. On the basis of this layer a continuative modification was realized by performing a “Click” reaction, namely, the Cu(I)-catalyzed 1,3-dipolar cycloaddition, with different alkynes. While the Click reaction was monitored by X-ray photoelectron spectroscopy, the morphology of the membranes in the different states of modification was examined with scanning electron microscopy and atomic force microscopy. The membrane properties were characterized by measurements of contact angle and clean water permeance, retention tests, and protein adsorption. Independent from the alkyne applied during the Click reaction, the clean water permeance is approximately 1200 L m–2 bar–1 h–1 and therefore slightly below the permeance of the pristine membrane. While the sharp molecular weight cutoff of the pristine membrane and all modified membranes is similar, antifouling properties as studied on the interaction of two model proteins (bovine serum albumin, hemoglobin) with the membranes turned out to be best for the membranes modified with 1-nonyne
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structure formation of integral asymmetric composite membranes of polystyrene block poly 2 vinylpyridine on a nonwoven
Macromolecular Materials and Engineering, 2012Co-Authors: Adina Jung, Volkan Filiz, Clarissa Abetz, Sofia Rangou, Volker AbetzAbstract:The formation of an integral asymmetric membrane composed of a cylinder-forming polystyrene-block-poly(2-vinylpyridine) on a nonwoven by using solvent casting followed by solvent/nonsolvent exchange (phase inversion) is reported for the first time. The influence of parameters such as solvent composition, evaporation time of the solution-cast block copolymer film before phase inversion, and immersion bath temperature is demonstrated. The optimized membranes are characterized in terms of stimuli-responsive water flux properties. The morphologies of the membranes as well as of the bulk of the block copolymer are imaged by scanning force microscopy, scanning electron microscopy, and transmission electron microscopy.
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synthesis and morphology of abc heteroarm star terpolymers of polystyrene polybutadiene and poly 2 vinylpyridine
Macromolecular Chemistry and Physics, 2000Co-Authors: Hanno Huckstadt, Astrid Gopfert, Volker AbetzAbstract:Three series of ABC heteroam star terpolymers with arms of polystyrene (St. polybutadiene (B) and poly(2-vinylpyridine) (V) were synthesized anionically using non-homopolymerizable maromonomers functionalized with a terminal 1.1-diphenylethylene unit. Ultra-thin samples from solution cast films were stained with OsO 4 , CH 3 I or I 2 and studied by transmission electron microscopy (TEM). The morphologies found include dense packings of cylinders with tetragonal or distorted hexagonal order, two hexagonal morphologies with V cylinders surrounded by six B and six S cylinders, where S and V switch places depending on the polymer composition, lamellas of V and S with B cylinders in the S lamella and smooth lamellae of all components. Some polymers were also characterized by small angle X-ray scattering (SAXS).
George A. Olah - One of the best experts on this subject based on the ideXlab platform.
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poly 4 vinylpyridine nitrating mixture complex pvp nm solid nitrating mixture equivalent for safe and efficient aromatic nitration
Green Chemistry, 2015Co-Authors: G Surya K Prakash, Laxman Gurung, Kevin E Glinton, Kavita Belligund, Thomas Mathew, George A. OlahAbstract:Friedel–Crafts type aromatic nitration has served as an indispensable reaction within both industrial and academic applications. However, growing concern over the use of copious amounts of strong acids has prompted the search for more environmentally friendly alternatives. Polymer-bound Bronsted acids, on the other hand, have been shown useful as convenient alternatives to liquid acids. Nitric acid and sulfuric acids have, therefore, been combined, both individually and as a mixture, with poly(4-vinylpyridine). The new solid acid systems have been used to nitrate both activated and deactivated arenes under mild conditions and proved to be effective nitrating agent.
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poly n vinylpyrrolidone h2o2 and poly 4 vinylpyridine h2o2 complexes solid h2o2 equivalents for selective oxidation of sulfides to sulfoxides and ketones to gem dihydroperoxides
ChemInform, 2014Co-Authors: G Surya K Prakash, Kevin E Glinton, Thomas Mathew, Anton Shakhmin, Sneha Rao, George A. OlahAbstract:Complexes of poly(N-vinylpyrrolidone) and poly(4-vinylpyridine) with hydrogen peroxide are prepared and their synthetic utility as solid hydrogen peroxide equivalents for the selective oxidation of sulfides to sulfoxides and ketones to gem-dihydroperoxides is studied.
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poly n vinylpyrrolidone h2o2 and poly 4 vinylpyridine h2o2 complexes solid h2o2 equivalents for selective oxidation of sulfides to sulfoxides and ketones to gem dihydroperoxides
Green Chemistry, 2014Co-Authors: G Surya K Prakash, Kevin E Glinton, Thomas Mathew, Anton Shakhmin, Sneha Rao, George A. OlahAbstract:Complexes of poly(N-vinylpyrrolidone) (PVD) and poly(4-vinylpyridine) (PVP) with hydrogen peroxide have been prepared and their synthetic utility as solid H2O2 equivalents for the selective oxidation of sulfides to sulfoxides and ketones to gem-dihydroperoxides has been studied. These complexes are convenient and safe alternatives to H2O2 solutions and it is found that various symmetric as well as unsymmetrical sulfides undergo oxidation under mild conditions to provide the respective sulfoxides in high yields. A series of gem-dihydroperoxides were obtained from the corresponding ketones in good yields under ambient conditions.
Mario Gauthier - One of the best experts on this subject based on the ideXlab platform.
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metal coordination induces phase segregation in amphipolar arborescent copolymers with a core shell corona architecture
Macromolecules, 2020Co-Authors: Jason Dockendorff, Martin Möller, Ahmed Mourran, Rustam A. Gumerov, Igor I. Potemkin, Mario GauthierAbstract:Arborescent copolymers with a core–shell–corona (CSC) architecture were synthesized and the topology of the molecules was challenged (constrained) through intramolecular interactions, resulting in phase separation breaking the symmetry of radial density. The inner poly(2-vinylpyridine) shell of these arborescent polystyrene-g-[poly(2-vinylpyridine)-b-polystyrene] molecules can self-assemble by binding metallic salts and acids in apolar and intermediate-polarity solvents. Upon loading with HAuCl4, the characteristics of the polymer templates govern the “loading sites” of the metal within the molecules. Unique morphologies were observed for the metal-loaded G0–G4 arborescent copolymers investigated, namely, spherical, toroidal, raspberry-like, spherical nanocage, and a new worm-in-sphere morphology. The reason for the emergence of such morphologies is the interplay among intramolecular interactions of unlike polymer segments, solvent selectivity, the entropic elasticity of the arborescent substrate, and phase segregation induced by coordination with the charged metallic species. Meanwhile, the stability of the arborescent molecules against aggregation provides intramolecular phase segregation with imposed “confined” geometry and thus leads to nonconventional morphologies. Furthermore, the size of the arborescent molecules is much smaller than that of other known particles (droplets) serving as confined geometries. Computer simulations were used to model the mesostructure of the arborescent copolymers, to demonstrate the influence of solvent selectivity, together with HAuCl4 loading, on the evolution of the morphology of the macromolecules.
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monomolecular films of arborescent polystyrene graft poly 2 vinylpyridine copolymers precursors to nanostructured carbon materials
European Polymer Journal, 2017Co-Authors: Mario GauthierAbstract:Abstract An arborescent polystyrene (PS)–graft–poly(2-vinylpyridine) (P2VP) copolymer of overall generation number G2, consisting of side chains with Mn ∼5000, served as template for the preparation of nanostructured carbon films. Spin casting of arborescent PS–graf–P2VP copolymers yielded monomolecular films of uniform thickness. The uniformity of the copolymer films was influenced by the casting solvent selected. Methanol solutions of the copolymers led to non-uniform layers consisting of large aggregates and voids. Homogeneous monolayer films were attained from copolymer solutions in tetrahydrofuran, which is a good solvent for both the PS and P2VP components. The copolymer molecules in the film were strongly flattened by adsorption forces, but recovered a spherical geometry after annealing in water. The water-annealed films could be directly converted into their analogous carbon films having nanodots on the surface by UV irradiation with concurrent pyrolysis. The pyrolyzed nanomaterials exhibited the characteristics of partially graphitic carbon with nitrogen.
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arborescent polystyrene graft poly 2 vinylpyridine copolymers as unimolecular micelles synthesis from acetylated substrates
Macromolecules, 2003Co-Authors: Mario Gauthier, Jason DockendorffAbstract:Branched copolymers with a dendritic structure were synthesized by grafting poly(2-vinylpyridine) (P2VP) side chains onto linear and arborescent polystyrene substrates of generations G0−G2 randomly functionalized with acetyl groups. The P2VP side chains were generated in tetrahydrofuran using 1,1-diphenyl-3-methylpentyllithium as the initiator. The living polymer was then titrated with a solution of acetylated substrate to yield the copolymer. The grafting yield reached 92−96% in the 0−25 °C range with LiCl as a reactivity modifier for the P2VP anions. Arborescent copolymers with Mw ≈ 5000 or 30 000 P2VP side chains were synthesized. The copolymers with short side chains contain 82−92 mol % P2VP units. For the long side chain systems, the P2VP content reaches over 97 mol %. These materials are characterized by a very compact structure, a narrow molecular weight distribution (Mw/Mn = 1.06−1.08), and a roughly geometric increase in branching functionality and molecular weight for successive generations. The...
Jeanfrancois Gohy - One of the best experts on this subject based on the ideXlab platform.
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supramolecular assemblies from poly styrene block poly 4 vinylpyridine diblock copolymers mixed with 6 hydroxy 2 naphthoic acid
Polymers, 2013Co-Authors: Bhavesh Bharatiya, Jean Marc Schumers, Elio Poggi, Jeanfrancois GohyAbstract:Supramolecular assemblies involving interaction of a small organic molecule, 2-hydroxy-6-Naphthoic acid (HNA), with poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers are utilized to obtain micellar structures in solution, nanostructured thin films on flat substrates and, finally, nanoporous thin films. The formation of hydrogen bonds between HNA and the poly(4-vinylpyridine) (P4VP) blocks is confirmed by spectroscopic measurements. The accordingly P4VP/HNA hydrogen-bonded complexes are poorly soluble in 1,4-dioxane, resulting in the formation of micellar structures with a P4VP/HNA core and a polystyrene (PS) corona. Those micelles have been spin-coated onto silicon wafers, resulting in nanostructured thin films consisting of P4VP/HNA dot-like features embedded in a PS matrix. The morphology of those films has been tuned by solvent annealing. Selective dissolution of HNA by methanol results in the formation of a nanoporous thin film. The P4VP/HNA nanodomains have been also cross-linked by borax, and the thin films have been further dissolved in a good solvent for PS, leading to micelles with a structure reminiscent of the thin films.
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supramolecular assemblies from poly styrene block poly 4 vinylpyridine diblock copolymers mixed with 6 hydroxy 2 naphthoic acid
Polymers, 2013Co-Authors: Bhavesh Bharatiya, Jean Marc Schumers, Elio Poggi, Jeanfrancois GohyAbstract:Supramolecular assemblies involving interaction of a small organic molecule, 2-hydroxy-6-Naphthoic acid (HNA), with poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers are utilized to obtain micellar structures in solution, nanostructured thin films on flat substrates and, finally, nanoporous thin films. The formation of hydrogen bonds between HNA and the poly(4-vinylpyridine) (P4VP) blocks is confirmed by spectroscopic measurements. The accordingly P4VP/HNA hydrogen-bonded complexes are poorly soluble in 1,4-dioxane, resulting in the formation of micellar structures with a P4VP/HNA core and a polystyrene (PS) corona. Those micelles have been spin-coated onto silicon wafers, resulting in nanostructured thin films consisting of P4VP/HNA dot-like features embedded in a PS matrix. The morphology of those films has been tuned by solvent annealing. Selective dissolution of HNA by methanol results in the formation of a nanoporous thin film. The P4VP/HNA nanodomains have been also cross-linked by borax, and the thin films have been further dissolved in a good solvent for PS, leading to micelles with a structure reminiscent of the thin films. © 2013 by the authors.
Jason Dockendorff - One of the best experts on this subject based on the ideXlab platform.
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metal coordination induces phase segregation in amphipolar arborescent copolymers with a core shell corona architecture
Macromolecules, 2020Co-Authors: Jason Dockendorff, Martin Möller, Ahmed Mourran, Rustam A. Gumerov, Igor I. Potemkin, Mario GauthierAbstract:Arborescent copolymers with a core–shell–corona (CSC) architecture were synthesized and the topology of the molecules was challenged (constrained) through intramolecular interactions, resulting in phase separation breaking the symmetry of radial density. The inner poly(2-vinylpyridine) shell of these arborescent polystyrene-g-[poly(2-vinylpyridine)-b-polystyrene] molecules can self-assemble by binding metallic salts and acids in apolar and intermediate-polarity solvents. Upon loading with HAuCl4, the characteristics of the polymer templates govern the “loading sites” of the metal within the molecules. Unique morphologies were observed for the metal-loaded G0–G4 arborescent copolymers investigated, namely, spherical, toroidal, raspberry-like, spherical nanocage, and a new worm-in-sphere morphology. The reason for the emergence of such morphologies is the interplay among intramolecular interactions of unlike polymer segments, solvent selectivity, the entropic elasticity of the arborescent substrate, and phase segregation induced by coordination with the charged metallic species. Meanwhile, the stability of the arborescent molecules against aggregation provides intramolecular phase segregation with imposed “confined” geometry and thus leads to nonconventional morphologies. Furthermore, the size of the arborescent molecules is much smaller than that of other known particles (droplets) serving as confined geometries. Computer simulations were used to model the mesostructure of the arborescent copolymers, to demonstrate the influence of solvent selectivity, together with HAuCl4 loading, on the evolution of the morphology of the macromolecules.
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arborescent polystyrene graft poly 2 vinylpyridine copolymers as unimolecular micelles synthesis from acetylated substrates
Macromolecules, 2003Co-Authors: Mario Gauthier, Jason DockendorffAbstract:Branched copolymers with a dendritic structure were synthesized by grafting poly(2-vinylpyridine) (P2VP) side chains onto linear and arborescent polystyrene substrates of generations G0−G2 randomly functionalized with acetyl groups. The P2VP side chains were generated in tetrahydrofuran using 1,1-diphenyl-3-methylpentyllithium as the initiator. The living polymer was then titrated with a solution of acetylated substrate to yield the copolymer. The grafting yield reached 92−96% in the 0−25 °C range with LiCl as a reactivity modifier for the P2VP anions. Arborescent copolymers with Mw ≈ 5000 or 30 000 P2VP side chains were synthesized. The copolymers with short side chains contain 82−92 mol % P2VP units. For the long side chain systems, the P2VP content reaches over 97 mol %. These materials are characterized by a very compact structure, a narrow molecular weight distribution (Mw/Mn = 1.06−1.08), and a roughly geometric increase in branching functionality and molecular weight for successive generations. The...