Effects of chain structures of corn starches on starch‐based superabsorbent polymers

Abstract

Biodegradable superabsorbent polymers (SAPs) were synthesized in this study by graft copolymerization of monomers (acrylic acid or acrylamide) onto amylose and amylopectin, respectively, using potassium persulfate as an initiator and N,N′‐methylenebisacrylamide as a cross‐linker. The main purpose of this study is to investigate the effects of the chain structures of corn starches on the grafting ratio (GR) and physicochemical properties of starch‐based SAPs including starch‐graft‐polyacrylic acid and starch‐graft‐polyacrylamide SAPs. The structure of these SAPs was characterized by FTIR, 13C nuclear magnetic resonance (13C‐NMR), and thermogravimetric analysis (TGA), and the GR was evaluated by acid hydrolysis. We also investigated their swelling kinetics and reswelling capacity. The results show that the water absorption capacity and GR of amylose graft copolymers are superior to those of amylopectin graft copolymers; this may be due to the differences in structures and physicochemical properties between amylose and amylopectin.