Thermogels Based on Block versus Gradient Terpolymers: Differences in the Nano- and Macro-Scale

In the present study, the effect of the distribution of repeated units in copolymers based on oligo-(ethylene glycol) methyl ether methacrylate (A), n-butyl methacrylate (B), and di-(ethylene glycol) methyl ether methacrylate (C) is reported and discussed for the first time. Several linear structures have been synthesized via group transfer polymerization, varying from statistical to gradient to block structures. Notably, among the other linear architectures, we report the one-pot synthesis of a forced gradient terpolymer and the investigation of its thermoresponsive and gelation properties. It is proven that the distribution of repeated units along the polymer chain governs the solubility and gelation of the copolymers, with the ABC and gradient structures being the best-performing. The self-assembled structures and aggregation mechanisms differ strongly for the ABC triblock and the gradient terpolymer, as revealed by synchrotron small-angle X-ray scattering. The promising results of the gradient structure open a new era for designing novel copolymers with potential applications in the biomedical sector.