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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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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 Unimolecular Micelles: Poly(γ-Benzyl l-Glutamate) Core Grafted with a Hydrophilic Shell by Copper(I)-Catalyzed Azide⁻Alkyne Cycloaddition Coupling.
Polymers, 2017Co-Authors: Mario Gauthier, Gregory Allan WhittonAbstract:Amphiphilic copolymers were obtained by grafting azide-terminated polyglycidol, poly(ethylene oxide), or poly(2-hydroxyethyl acrylate) chain segments onto alkyne-functionalized Arborescent poly(γ-benzyl l-glutamate) (PBG) cores of generations G1–G3 via copper(I)-catalyzed azide–alkyne Huisgen cycloaddition (CuAAC) coupling. The alkyne functional groups on the Arborescent PBG substrates were either distributed randomly or located exclusively at the end of the chains added in the last grafting cycle of the core synthesis. The location of these coupling sites influenced the ability of the Arborescent copolymers to form unimolecular micelles in aqueous environments: The chain end grafting approach provided enhanced dispersibility in aqueous media and favored the formation of unimolecular micelles in comparison to random grafting. This is attributed to a better defined core-shell morphology for the copolymers with end-grafted shell segments. Aqueous solubility also depended on the type of material used for the shell chains. Coupling by CuAAC opens up possibilities for grafting a broad range of polymers on the Arborescent substrates under mild conditions.
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Synthesis of Arborescent Polymers by “Click” Grafting
MRS Proceedings, 2014Co-Authors: Toufic Aridi, Mario GauthierAbstract:ABSTRACTA novel method was developed for the preparation of Arborescent (dendritic graft) polymers, by successive grafting reactions of linear chain segments using alkyne-azide “click” chemistry coupling. A linear polystyrene substrate was thus randomly functionalized with acetylene functionalities, by acetylation and further reaction with propargyl bromide in the presence of potassium hydroxide and 18-crown-6 in toluene. The anionic polymerization of styrene was achieved with 6-tert-butyldimethylsiloxy-hexyllithium to obtain polystyrene with a protected hydroxyl chain end. Deprotection of the hydroxyl group, followed by conversion into tosyl and azide functionalities yielded the material serving as side chains in the grafting reactions. Coupling of the azide-terminated side chains with the acetylene-functionalized substrate in the presence of a Cu(I) catalyst proceeded in up to 93% yield. Additional cycles of substrate functionalization and side chain coupling led to Arborescent polymers of generations G1 and G2, with low polydispersity indices (Mw/Mn≈ 1.1), in 60-84% yield. These polymers are characterized by a very compact structure, and molecular weights increasing geometrically over successive generations. A similar methodology was also shown to work for the synthesis of Arborescent polybutadiene systems, using azide-functionalized substrates and alkyne-terminated side chains. The coupling reaction proceeded in up to 76% yield under optimized conditions for these systems.
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Synthesis of Arborescent polystyrene‐g‐[poly(2‐vinylpyridine)‐b‐polystyrene] core–shell–corona copolymers
Journal of Polymer Science Part A: Polymer Chemistry, 2014Co-Authors: Jason Dockendorff, Mario GauthierAbstract:Arborescent copolymers with a core-shell-corona (CSC) architecture, incorporating a polystyrene (PS) core, an inner shell of poly(2-vinylpyridine), P2VP, and a corona of PS chains, were obtained by anionic polymerization and grafting. Living PS-b-P2VP-Li block copolymers serving as side chains were obtained by capping polystyryllithium with 1,1-diphenylethylene before adding 2-vinylpyridine. A linear or Arborescent (generation G0 – G3) PS substrate, randomly functionalized with acetyl or chloromethyl coupling sites, was then added to the PS-b-P2VP-Li solution for the grafting reaction. The grafting yield and the coupling efficiency observed in the synthesis of the Arborescent PS-g-(P2VP-b-PS) copolymers were much lower than for analogous coupling reactions previously used to synthesize Arborescent PS homopolymers and PS-g-P2VP copolymers from the same types of coupling sites. It was determined from static and dynamic light scattering analysis that PS-b-P2VP formed aggregates in THF, the solvent used for the synthesis. This presumably hindered coupling of the macroanions with the substrate, and explains the low grafting yield and coupling efficiency observed in these reactions. Purification of the crude products was also problematic due to the amphipolar character of the CSC copolymers and the block copolymer contaminant. A new fractionation method by cloud-point centrifugation was developed to purify copolymers of generations G1 and above. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1075–1085
Martin Möller - 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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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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Amphiphilic Arborescent Copolymers and Microgels: From Unimolecular Micelles in a Selective Solvent to the Stable Monolayers of Variable Density and Nanostructure at a Liquid Interface
ACS applied materials & interfaces, 2017Co-Authors: Rustam A. Gumerov, Martin Möller, Andrey A. Rudov, Walter Richtering, Igor I. PotemkinAbstract:Amphiphilic Arborescent block copolymers of two generations (G2 and G3) and polymer microgels, obtained via cross-linking of diblock copolymers, were studied in a selective solvent and at liquid interface via dissipative particle dynamics (DPD) simulations. Depending on the primary structure, single Arborescent macromolecules in selective solvent can have both core–corona and multicore structures. Self-assembly of the G2, G3, and microgels in the selective solvent is compared with equivalent linear diblock copolymers. The latter self-assemble into spherical micelles of large enough aggregation number. On the contrary, stability of unimolecular micelles is a feature of the Arborescent copolymers and microgels, whereas their ability to aggregate is very low. Adsorption of the single molecules at liquid (oil–water) interface leads to their flattening and segregation of the amphiphilic blocks: hydrophilic and hydrophobic blocks are exposed toward water and oil, respectively. Depending on the character of inte...
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Melt rheology of Arborescent graft polystyrenes
Macromolecules, 1998Co-Authors: Mark A. Hempenius, Mario Gauthier, Wf Wim Zoetelief, Martin MöllerAbstract:Arborescent graft or comb-burst polymers are highly branched, high molecular weight polymers that are constructed from linear polymer chains by a cascade grafting process. The Arborescent graft polystyrenes studied here were prepared by a “graft on graft” synthetic strategy employing anionically prepared branches, which led to well-defined branched polymers with controlled branch lengths and low polydispersities. The dynamic mechanical behavior of these Arborescent graft polystyrenes in the melt was studied as a function of branch length and grafting generation. Terminal relaxation times and zero-shear viscosities of the lower-generation Arborescent graft polymers increase progressively with the molecular weight of the branches. Even in the case of the highly branched molecules, all samples demonstrated viscous flow behavior at small shear rates. The frequency dependence of the dynamic moduli changed with increasing number of grafting generations showing the features of a cross-linking polymer at the gel ...
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Arborescent graft polybutadienes
Macromolecules, 1997Co-Authors: Mark A. Hempenius, Walter Michelberger, Martin MöllerAbstract:Cascade-branched, “graft on graft” polybutadienes, denoted Arborescent graft polymers, were prepared by hydrosilylation of polybutadiene vinyl groups with chlorodimethylsilane, followed by grafting with living polybutadiene chains. Repeated hydrosilylation−anionic grafting cycles led to a treelike outward growth, yielding well-defined, spherically shaped macromolecules. The molecular weight of the materials increased dramatically with each grafting cycle, since polymer chains rather than small molecules were used as building blocks. The materials were characterized by means of gel permeation chromatography, static light scattering measurements, and viscosimetry.
Elizabeth R. Gillies - One of the best experts on this subject based on the ideXlab platform.
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synthesis and properties of Arborescent polyisobutylene poly ethylene oxide graft copolymers a comparison of linear and Arborescent graft copolymer architectures
Polymer International, 2015Co-Authors: Solmaz Karamdoust, Patrick Crewdson, Mark Ingratta, Elizabeth R. GilliesAbstract:Polymer architecture can have a significant effect on the properties and potential applications of materials. In this study, Arborescent polyisobutylene (PIB)-poly(ethylene oxide) (PEO) graft copolymers with varying PEO content were synthesized from Arborescent PIB-co-polyisoprene and compared with linear PIB-PEO graft copolymers. By AFM imaging, phase separation was detected in a 48 wt% PEO Arborescent copolymer. Tensile testing revealed that, in general, increasing PEO content led to increased tensile strength and Young's modulus but decreased elongation at break. Arborescent analogues exhibited lower elongation at break and lower strength compared with linear analogues but also less plastic deformation and yielding behaviour. Like linear analogues of comparable PEO content, films of the Arborescent graft copolymers resisted the adsorption of rhodamine-labelled fibrinogen, suggesting that they may also exhibit non-fouling properties. Finally, the assembly of these amphiphilic copolymers in aqueous solution was investigated. Unlike the linear analogues, the sizes of the assemblies were not greatly affected by their method of preparation. This work demonstrates that it is possible to prepare PIB-based materials with a wide range of interesting properties by tuning not only the content of PEO but also the architectures of the macromolecules. © 2014 Society of Chemical Industry
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Synthesis and properties of Arborescent polyisobutylene‐poly(ethylene oxide) graft copolymers: a comparison of linear and Arborescent graft copolymer architectures
Polymer International, 2014Co-Authors: Solmaz Karamdoust, Patrick Crewdson, Mark Ingratta, Elizabeth R. GilliesAbstract:Polymer architecture can have a significant effect on the properties and potential applications of materials. In this study, Arborescent polyisobutylene (PIB)-poly(ethylene oxide) (PEO) graft copolymers with varying PEO content were synthesized from Arborescent PIB-co-polyisoprene and compared with linear PIB-PEO graft copolymers. By AFM imaging, phase separation was detected in a 48 wt% PEO Arborescent copolymer. Tensile testing revealed that, in general, increasing PEO content led to increased tensile strength and Young's modulus but decreased elongation at break. Arborescent analogues exhibited lower elongation at break and lower strength compared with linear analogues but also less plastic deformation and yielding behaviour. Like linear analogues of comparable PEO content, films of the Arborescent graft copolymers resisted the adsorption of rhodamine-labelled fibrinogen, suggesting that they may also exhibit non-fouling properties. Finally, the assembly of these amphiphilic copolymers in aqueous solution was investigated. Unlike the linear analogues, the sizes of the assemblies were not greatly affected by their method of preparation. This work demonstrates that it is possible to prepare PIB-based materials with a wide range of interesting properties by tuning not only the content of PEO but also the architectures of the macromolecules. © 2014 Society of Chemical Industry
Solmaz Karamdoust - One of the best experts on this subject based on the ideXlab platform.
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synthesis and properties of Arborescent polyisobutylene poly ethylene oxide graft copolymers a comparison of linear and Arborescent graft copolymer architectures
Polymer International, 2015Co-Authors: Solmaz Karamdoust, Patrick Crewdson, Mark Ingratta, Elizabeth R. GilliesAbstract:Polymer architecture can have a significant effect on the properties and potential applications of materials. In this study, Arborescent polyisobutylene (PIB)-poly(ethylene oxide) (PEO) graft copolymers with varying PEO content were synthesized from Arborescent PIB-co-polyisoprene and compared with linear PIB-PEO graft copolymers. By AFM imaging, phase separation was detected in a 48 wt% PEO Arborescent copolymer. Tensile testing revealed that, in general, increasing PEO content led to increased tensile strength and Young's modulus but decreased elongation at break. Arborescent analogues exhibited lower elongation at break and lower strength compared with linear analogues but also less plastic deformation and yielding behaviour. Like linear analogues of comparable PEO content, films of the Arborescent graft copolymers resisted the adsorption of rhodamine-labelled fibrinogen, suggesting that they may also exhibit non-fouling properties. Finally, the assembly of these amphiphilic copolymers in aqueous solution was investigated. Unlike the linear analogues, the sizes of the assemblies were not greatly affected by their method of preparation. This work demonstrates that it is possible to prepare PIB-based materials with a wide range of interesting properties by tuning not only the content of PEO but also the architectures of the macromolecules. © 2014 Society of Chemical Industry
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Synthesis and properties of Arborescent polyisobutylene‐poly(ethylene oxide) graft copolymers: a comparison of linear and Arborescent graft copolymer architectures
Polymer International, 2014Co-Authors: Solmaz Karamdoust, Patrick Crewdson, Mark Ingratta, Elizabeth R. GilliesAbstract:Polymer architecture can have a significant effect on the properties and potential applications of materials. In this study, Arborescent polyisobutylene (PIB)-poly(ethylene oxide) (PEO) graft copolymers with varying PEO content were synthesized from Arborescent PIB-co-polyisoprene and compared with linear PIB-PEO graft copolymers. By AFM imaging, phase separation was detected in a 48 wt% PEO Arborescent copolymer. Tensile testing revealed that, in general, increasing PEO content led to increased tensile strength and Young's modulus but decreased elongation at break. Arborescent analogues exhibited lower elongation at break and lower strength compared with linear analogues but also less plastic deformation and yielding behaviour. Like linear analogues of comparable PEO content, films of the Arborescent graft copolymers resisted the adsorption of rhodamine-labelled fibrinogen, suggesting that they may also exhibit non-fouling properties. Finally, the assembly of these amphiphilic copolymers in aqueous solution was investigated. Unlike the linear analogues, the sizes of the assemblies were not greatly affected by their method of preparation. This work demonstrates that it is possible to prepare PIB-based materials with a wide range of interesting properties by tuning not only the content of PEO but also the architectures of the macromolecules. © 2014 Society of Chemical Industry
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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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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Synthesis of Arborescent polystyrene‐g‐[poly(2‐vinylpyridine)‐b‐polystyrene] core–shell–corona copolymers
Journal of Polymer Science Part A: Polymer Chemistry, 2014Co-Authors: Jason Dockendorff, Mario GauthierAbstract:Arborescent copolymers with a core-shell-corona (CSC) architecture, incorporating a polystyrene (PS) core, an inner shell of poly(2-vinylpyridine), P2VP, and a corona of PS chains, were obtained by anionic polymerization and grafting. Living PS-b-P2VP-Li block copolymers serving as side chains were obtained by capping polystyryllithium with 1,1-diphenylethylene before adding 2-vinylpyridine. A linear or Arborescent (generation G0 – G3) PS substrate, randomly functionalized with acetyl or chloromethyl coupling sites, was then added to the PS-b-P2VP-Li solution for the grafting reaction. The grafting yield and the coupling efficiency observed in the synthesis of the Arborescent PS-g-(P2VP-b-PS) copolymers were much lower than for analogous coupling reactions previously used to synthesize Arborescent PS homopolymers and PS-g-P2VP copolymers from the same types of coupling sites. It was determined from static and dynamic light scattering analysis that PS-b-P2VP formed aggregates in THF, the solvent used for the synthesis. This presumably hindered coupling of the macroanions with the substrate, and explains the low grafting yield and coupling efficiency observed in these reactions. Purification of the crude products was also problematic due to the amphipolar character of the CSC copolymers and the block copolymer contaminant. A new fractionation method by cloud-point centrifugation was developed to purify copolymers of generations G1 and above. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1075–1085