Enhanced sustained responsive-systems based on anionically modified gelatin-containing hybrid gels: A route to correlate physico-mechanical and swelling properties

Anionically modified gelatin-based multi-responsive hybrid gels were prepared by free radical copolymerization of acrylamide (AAm) and itaconic acid (IA) in varying amounts of gelatin (GLN). Influence of composition on physicochemical and mechanical properties was assessed. Maximum degradation temperatures of hybrids increased with addition of GLN to PAAm/IA network. Equilibrium swelling of hybrid PAAm/IA-GLNs was studied in water as a function of GLN content in the range of 0.075–0.750% (w/v). By examining the variation of the compression elastic modulus of hybrids with GLN, a correlation was obtained for the dependence of the effective crosslink density on the GLN content. pH sensitive swelling of hybrids exhibited a double-step increase with the S-shaped curve around pH 4.7 and 8.0. In studies evaluating the swelling tendency in various solvents, Hofmeister series and various swelling temperatures, it was found that swelling kinetics in NaNO₃ solutions proceeds by Fickian diffusion and Schott's pseudo-second order model can be effectively used to evaluate swelling kinetics. Hybrid gels were applied to adsorption of cationic methylene blue (MB) and malachite green (MG) as model contaminating dyes from aqueous solutions. Accordingly, GLN-based hybrid gels could be a good adsorbent for the removal of cationic dyes from the contaminated waters.