Self-Assembly Behavior of Thermoresponsive Oligo(ethylene glycol) Methacrylates Random Copolymer

A well-defined random copolymer containing 2-(2-methoxyethoxy) ethyl methacrylate (MEO₂MA, M_n = 188 g/mol) and poly­(ethylene glycol) methyl ether methacrylate (PEGMA, M_n = 2080 g/mol) (poly­(MEO₂MA-co-PEGMA₂₀₈₀)), M_n = 17300 g/mol) was synthesized using the atom transfer radical polymerization (ATRP) process, and its thermoresponsive behaviors in aqueous solution were investigated. In comparison to other temperature-sensitive random copolymers based on oligo­(ethylene glycol) methacrylates, this copolymer exhibited an unusual thermally induced two-stage aggregation process. The copolymer chains associate at the first thermal transition followed by a rearrangement process at the second thermal transition to produce a stable core–shell micellar structure. The morphology of the micelle comprises of a methacrylate core stabilized by the longer ethylene glycol segments (M_n = 2080 g/mol) shell.