Thermogelling Formulations based on In-House synthesized ethylene Glycol-Containing ABC triblock copolymers and their mixtures with diblocks

Abstract

This study investigated the thermoresponsive properties of a novel series of ABC triblock terpolymers synthesized from ethylene glycol (EG)-based comonomers with varying lengths of PEG pendant chains. The terpolymers, with a targeted molar mass of 8100 g/mol, were synthesized using sequential Group Transfer Polymerization (GTP) and featured a range of compositions. Specifically, the hydrophobic content of methoxy ethylene glycol methacrylate (MEGMA, block B) was varied between 25 % and 55 % w/w, with corresponding adjustments to the thermoresponsive oligo(ethylene glycol) methyl ether methacrylate (OEGMA with an average molar mass of 300 g/mol, block A) and di(ethylene glycol) methyl ether methacrylate (DEGMA, block C), resulting in 16 distinct compositions. The cloud point temperatures were determined via turbidimetry, while dynamic light scattering (DLS) was employed to assess micellar self-assembly behavior. Of the 16 terpolymers, three demonstrated the ability to form thermogels. Blending these terpolymers with a high-performing diblock copolymer enabled tunable sol-to-gel transitions and identified a specific concentration that facilitated thermogel formation at physiological temperatures. Notably, the M1 polymer solution—a mixture of a triblock terpolymer and its diblock counterpart, both with 50 % w/w MEGMA content—exhibited superior sustained release of the sodium fluorescein model drug, outperforming the industry-standard Pluronic F127. This study underscores the importance of balancing hydrophilicity and hydrophobicity for effective sol–gel transitions in these novel triblock terpolymers and presents a straightforward yet effective strategy for diversifying polymer mixtures to fine-tune the gelation range and enhance versatility.