Synthesis of poly(methyl methacrylate)-poly(poly(ethylene glycol) methacrylate)-polyisobutylene ABCBA pentablock copolymers by combining quasiliving carbocationic and atom transfer radical polymerizations and characterization thereof

Szabó, Ákos and Wacha, András Ferenc and Thomann, R. and Szarka, Györgyi Éva and Bóta, Attila and Iván, Béla (2015) Synthesis of poly(methyl methacrylate)-poly(poly(ethylene glycol) methacrylate)-polyisobutylene ABCBA pentablock copolymers by combining quasiliving carbocationic and atom transfer radical polymerizations and characterization thereof. JOURNAL OF MACROMOLECULAR SCIENCE-PURE AND APPLIED CHEMISTRY, 52. pp. 252-259. ISSN 1060-1325

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Abstract

Novel, unique amphiphilic pentab lock terpolymers consisting of the highly hydrophobic polyisobutylene (PIB) mid - segment attached to the hydrophilic combshaped poly(poly(ethylene glycol ) methacrylate) (PPEGMA) polymacromonomer chains, which are coupled to poly(methyl methacrylate) (PMMA) outer segments were synthesized by the combination of quasiliving carbocationic polymerization and atom transfer radical polymerization ( ATRP ) . First, a bifunctional PIB macroinitiator w as prepared by quasiliving carbocationic polymerization and subsequent quantitative chain end derivatizations. ATRP of PEGMAs with different molecular weights (M n = 188, 300 and 475 g/mol) led to triblock copolymers which were further reacted with MMA under ATRP conditions to obtain P MMA - PPE G MA - PIB - PPEGMA - PMMA AB CB A - type pen ta block copolymers . It was found that slow initi ation takes place between the PIB macroinitiator and PEGMA macromonomers with higher molecular weights via ATRP . ATRP of MMA with the resulting block copolymers composed of PIB and PPEGMA chain segments led t o the desired block copolymers with high initiating efficiency. Investigations of the resulting pentablock copolymers by DSC, SAXS and phase mode AFM revealed that nanophase separation occurs in these new macromolecular structures with average domain dista nces of 11 - 14 nm, and local lamellar self - assembly takes place in the pentablocks with PPEGMA polymacromonomer segments of PEGMAs with M n of 118 g/mol and 300 g/mol , while disordered nanophases are observed in the block copolymer with PEGMA having molecula r weight of 475 g/mol. These new amphiphilic block copolymers composed of biocompatible chain segments can find applications in a variety of advanced fields.

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