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

SO 2 -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 γ- 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 NaN 3 , followed by the copper-mediated 1,3-dipolar cycloaddition, and subsequent ion-exchange reaction. 1 H NMR analysis revealed that SO 2 interacted with 1,2,3-triazole group leading to polymer aggregation. The P4 /SO 2 aqueous solution is multi-responsive that can be triggered by gas (N 2 /SO 2 ), temperature, and oxidation (i.e., H 2 O 2 ). Poly(vinyl alcohol) (PVA) hydrogel modified by P4 and BaSO 3 particles were prepared, the resulting hydrogel showed improved mechanical properties in terms of both stiffness and toughness.