Effect of Composition on the Thermo-Induced Aggregation of Poloxamer-Analogue Triblock Terpolymers

Thermoresponsive polymers hold great promise for biomedical applications due to their thermo-induced phase transitions. However, challenges including controlling transition temperatures, aggregate behavior, or complex synthesis, have limited their broader use. In this study, six ABC triblock terpolymers were synthesized via group transfer polymerization, targeting a molar mass of 8000 g/mol with varying compositions. The terpolymers consist of hydrophilic oligo(ethylene glycol) methyl ether methacrylate (average molar mass = 300 g/mol, OEGMA300), hydrophobic di(propylene glycol) methyl ether methacrylate (diPGMA), and less-hydrophilic di(ethylene glycol) methyl ether methacrylate (DEGMA). Systematic characterizations of properties related to thermo-induced aggregation, including cloud point temperature, aggregate morphology, and chain immobilization, identified a unique dual-stage phase transition in the terpolymer containing 45 wt % OEGMA300, 35 wt % diPGMA, and 20 wt % DEGMA. Instead of directly agglomerating into globular aggregates, this terpolymer transitioned from spherical micelles to vesicular species, offering valuable insights for the design of controllable and responsive polymer systems.