PEG-based methacrylate tetrablock terpolymers: how does the architecture control the gelation?

Abstract

An ABCA tetrablock terpolymer with excellent thermogelling properties in aqueous solutions has been identified by tuning the architecture of ethylene glycol-based tetrablock terpolymers. Specifically, it gels at concentrations as low as 5 wt % at a wide range of temperatures, including body temperature. Nine tetrablock copolymers based on hydrophilic oligo(ethylene glycol) methyl ether methacrylate with average molar mass (MM) 300 g mol–1 (OEGMA300, A), hydrophobic n-butyl methacrylate (BuMA, B), and hydrophilic and thermoresponsive di(ethylene glycol) methyl ether methacrylate (DEGMA, C) were synthesized and screened. The MM and composition were kept constant, while the tetrablock architecture was systematically varied. Specifically, copolymers with (i) two OEGMA300 blocks (ABCA, ABAC, and ACAB), (ii) two BuMA blocks (BACB, BABC, and ABCB), and (iii) two DEGMA blocks (CABC, CACB, and ACBC) were fabricated. The self-assembly and thermoresponsive properties of their aqueous solutions were investigated with the polymer architecture governing their solubility, micellization, thermoresponsive, and rheological properties.