Microwave-assisted synthesis and swelling behavior of poly lactic acid (PLA) grafted Cordia dichotoma gum-based hydrogels

GBHs, or gum-based hydrogels, or superabsorbents, are derived from natural gums. In their unmodified form, these natural polysaccharides may be limited in their application due to physical matrix erosion caused by intensive swelling. Therefore, tailoring their structure to achieve desired swelling properties is crucial. In this study, a biodegradable gum (CDG) was extracted from Cordia dichotoma fruits using ethanol, and its corresponding grafted copolymer aka CDG-g-PLA was synthesized for the first time by graft copolymerization of poly (lactic acid) (PLA) onto the backbone of CDG by exposure to microwave irradiation. The synthesized CDG-g-PLA copolymer was characterized by FTIR, SEM, XRD, TGA, DSC, and DLS measurements to study its physico-chemical properties. The FTIR analysis proved the grafting of PLA at the –OH group on the backbone of CDG biopolymer which was supported by all other characterizations. The XRD patterns showed a broad peak at 2θ = 26.4 for CDG-g-PLA confirming its amorphous nature. DLS measurements exhibited that particles in the CDG and CDG-g-PLA copolymer formed a coarse suspension in water with particle sizes > 1 µm. The negative value of zeta potential results confirmed the hydrogels to be anionic. The swelling of CDG-g-PLA in water was measured and found to be significantly lower than CDG, making them novel candidates for drug-delivery and sustainable food packaging applications.