A comparative study of starch-g-(glycidyl methacrylate)/synthetic polymer-based hydrogels

Chemical modification reactions and blending formation are two alternatives used to improve the properties of starch-based materials. This work used both approaches to evaluate how they would affect the properties of hydrogels. The hydrogels were based on corn starch (St), modified with glycidyl methacrylate (GMA; starch-g-GMA; GMASt), and blended with N,N′-dimethylacrylamide (DMAAm; GMAStxDMAAmy) or sodium acrylate (SA; GMAStxSAy). The results confirmed that the pure GMASt matrix had a low swelling degree (≈3 g g−1), but when blended with the synthetic polymers, this value reached ≈10 g g−1 (sample GMASt25DMAAm75). All matrices showed responsiveness towards pH variations. In general, they swelled more at pH 5 than at pH 7. While DMAAm had more influence on the swelling degree, SA was more efficient as a mechanical enhancer. Increasing 25 % of the amount of SA in the blend increased Young's Modulus by a factor of ≈10 times. It confirmed that both polymers effectively change the properties of GMASt, but in different ways.