Amylopectin Copolymers Grafted with RAFT-Obtained Synthetic Polymers: Synthesis and Aqueous Solution Behavior

According to the requirements of modern society for durable biomaterials with multiple functionalities, the principal target of this study was to apply the "grafting to" scheme on the synthesis of several hybrid copolymers based on amylopectin (AMP) and poly(N-isopropylacrylamide) (PNIPAM), poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA), and poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) as synthetic polymer components, thus obtaining hybrid copolymers responsive to different stimuli, such as temperature, pH, and ionic strength. The synthetic polymers were synthesized by reversible addition-fragmentation chain transfer polymerization and contain reactive carboxyl groups attached to one end of the polymeric chains. The successful synthesis of novel graft copolymers AMP-g-PNIPAM, AMP-g-PDMAEMA, and AMP-g-POEGMA was confirmed by ATR-FTIR and ¹H NMR spectroscopies, by evidencing the appearance of new aliphatic ether bonds as a consequence of covalent grafting of the synthetic polymers onto the AMP chains. The pH, temperature, and ionic strength responsiveness of the newly obtained copolymers' aqueous solutions were followed by dynamic and electrophoretic light scattering analysis, revealing the intra/interchain self-assembly depending on the ionizable groups present in their structure, according to their protonation or deprotonation equilibria.