SO2, temperature, and oxidation multi-responsive homopolypeptide: Synthesis, characterization, and exploration of their potential applications

SO2-responsive homopolypeptide with tri(ethylene glycol), 1,2,3-triazole linkages and N-butylimidazolium iodide pendants (P4) were prepared by the ring-opening polymerization of gamma-2-(2-(2-chloroethoxy)ethoxy)ethyl-L-glutamic acid based N-carboxyanhydride then post-polymerization to the side-chain, by the nucleophilic substitution of the chloro group in the presence of NaN3, followed by the copper-mediated 1,3-dipolar cycloaddition, and subsequent ion-exchange reaction. H-1 NMR analysis revealed that SO2 interacted with 1,2,3-triazole group leading to polymer aggregation. The P4/SO2 aqueous solution is multi-responsive that can be triggered by gas (N 2 /SO2), temperature, and oxidation (i.e., H2O2). Poly(vinyl alcohol) (PVA) hydrogel modified by P4 and BaSO3 particles were prepared, the resulting hydrogel showed improved mechanical properties in terms of both stiffness and toughness.