Synthesis, characterization and water retention study of biodegradable Gum ghatti-poly(acrylic acid-aniline) hydrogels

A natural polysaccharide, Gum ghatti (Gg), was modified to prepare cross-linked hydrogels using the grafting method initiated by gamma-radiation. Acrylic acid (AA) and aniline monomers were used as the grafted monomers. Grafted copolymer based on Gg and AA was synthesized using N, N′-methylene-bis-acrylamide as a cross linker. The effects of monomer and cross linker concentration, gamma dose and the amount of solvent on the grafting percentage and percentage swelling were investigated. The degree of grafting and percentage swelling were found to be greatly dependent on the reaction parameters. Whereas, aniline monomer was absorbed into the network of Gg-cl-poly(AA), followed by a polymerization reaction between aniline monomer initiated by gamma-radiation. Biodegradation of synthesized hydrogels was also investigated using a composting soil method and Gg-cl-poly(AA-ipn-aniline) showed better degradation efficiency in comparison to Gg-cl-poly(AA). Furthermore, the degraded sample was characterized by FT-IR and surface morphology by SEM. Our results showed that Gg-cl-poly(AA) degraded at a rate of ∼6.1% after 6 days, whereas the degradation rate for Gg-cl-poly(AA-IPN-aniline) was ∼10%. Application of hydrogels to improve the water retention properties of different soils was studied for agricultural purposes and found that the IPN hydrogel can improve the moisture retention capacity of soil for cultivation.