Biobased oleyl glycidyl ether: copolymerization with ethylene oxide, postmodification, thermal properties, and micellization behavior

Abstract

Oleyl glycidyl ether (OlGE) is a highly hydrophobic monomer synthesized from a biobased fatty alcohol and epichlorohydrin. When combined with hydrophilic monomethoxy poly(ethylene glycol) (mPEG) macroinitiators, well-defined, highly amphiphilic AB block copolymers are obtained via anionic ring-opening polymerization (Đ ≤ 1.08). Surprisingly, an investigation of the copolymerization kinetics of OlGE and ethylene oxide revealed an almost ideally random copolymerization (r_EO = 1.27, r_OlGE = 0.78) despite the significant structural differences. Both statistical and block copolymers were investigated regarding their behavior in aqueous solution. The block copolymers of the type mPEG-b-POlGE featured two distinct melting temperatures (T_ms). Besides a melting transition of mPEG, a second T_m is attributed to the crystallization of the cis-alkenyl side chains of the OlGE units. Varying degrees of side chain hydrogenation of the POlGE homopolymer using potassium azodicarboxylate (PADA) allowed for tailoring of the T_m. The thiol–ene click reaction permitted subsequent functionalization. This work does not merely highlight the prospect of novel polyether surfactants, it also suggests the potential of biobased long-chain polyethers for the development of drug delivery systems featuring temperature-controlled release.