Polynorbornene‐g‐poly(ethylene oxide) Through the Combination of ROMP and Nitroxide Radical Coupling Reactions

Abstract

ABSTRACTGrafting‐onto and grafting‐through strategies for preparing polynorbornene‐g‐poly(ethylene oxide)s (PNB‐g‐PEO) have been developed through a combination of ring‐opening metathesis polymerization (ROMP) and nitroxide radical coupling (NRC). 2‐Bromoisobutyrate‐functionalized poly(ethylene oxide) monomethyl ether 2000 (PEO45‐Br) was successfully anchored on a 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (TEMPO)‐containing polynorbornene backbone of number‐average degree of polymerization () of 100 through the grafting‐onto strategy, resulting in PNB‐g‐PEO with a grafting yield ranging up to 90%. ROMP of ω‐exo‐norbornenyl PEO45 monomethyl ether macromonomer issued from NRC between a nitroxide‐functionalized norbornene and PEO45‐Br has allowed to reach a well‐defined bottlebrush copolymer with a backbone of 100 while retaining a low dispersity of 1.09. The effect of the grafting‐onto versus grafting‐through strategy and, consequently, of the grafting density, was investigated by thermal analyses and self‐assembly properties of the PNB100‐g‐PEO45. A substantial reduction of crystallinity was observed for PNB‐g‐PEO prepared via the grafting‐through route. Preliminary study of the self‐assembling properties has shown that the graft copolymers form monodisperse spherical particles in aqueous solution. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 645–653