Self-Assembly Behavior\nof Thermoresponsive Oligo(ethylene\nglycol) Methacrylates Random Copolymer

Abstract

A well-defined random copolymer containing 2-(2-methoxyethoxy)\nethyl methacrylate (MEO₂MA, <i>M</i>_n = 188 g/mol) and poly­(ethylene glycol) methyl ether methacrylate\n(PEGMA, <i>M</i>_n = 2080 g/mol) (poly­(MEO₂MA-<i>co</i>-PEGMA₂₀₈₀)), <i>M</i>_n = 17300 g/mol) was synthesized using the atom transfer\nradical polymerization (ATRP) process, and its thermoresponsive behaviors\nin aqueous solution were investigated. In comparison to other temperature-sensitive\nrandom copolymers based on oligo­(ethylene glycol) methacrylates, this\ncopolymer exhibited an unusual thermally induced two-stage aggregation\nprocess. The copolymer chains associate at the first thermal transition\nfollowed by a rearrangement process at the second thermal transition\nto produce a stable core–shell micellar structure. The morphology\nof the micelle comprises of a methacrylate core stabilized by the\nlonger ethylene glycol segments (<i>M</i>_n =\n2080 g/mol) shell.