Synthesis and Study on Effect of Various Chemical Conditions on the Swelling Property of Collagen- g -poly(AA- co -IA) Superabsorbent Hydrogel

In this work, a novel family of salt-responsive polymeric hydrogel based on collagen was prepared via simultaneously graft copolymerization of acrylic monomers, acrylic acid (AA) and itaconic acid (IA) onto collagen backbones by a free radical polymerization technique using ammonium persulfate (APS) as initiator and methylene bisacrylamide (MBA) as a crosslinker. The effect of grafting variables, i.e. AA/IA weight ratio and concentration of MBA and APS, was systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The water absorbency increased with increasing the AA/IA amount in the monomer feed due to formation of polyelectrolyte and then become constant. The swelling of the hydrogel samples in town water and saline solution (0.15 mol/L LiCl,NaCl,KCl, CaCl₂ and AlCl₃) was examined. Results indicated that the swelling capacity decreased with an increase charge of cation. This behavior can be attributed to charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations.finally,a mechanism for hydrogel formation was proposed and the structure of the product was established using Fourier transform infrared (FTIR) and Scanning Electron Microscopy (SEM) spectroscopies. Also, thermogravimetric analysis showed the thermal stabilities of the hydrogels.