Semi-IPN superabsorbent polymer based on itaconic acid and polyvinyl alcohol with improved gel strength and salt resistance

Abstract

Semi-interpenetrating polymer network (semi-IPN) technology was introduced in order to improve the gel strength and salt resistance of itaconic acid (IA)-based superabsorbent polymers (SAPs). A semi-IPN SAP based on IA and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) was synthesized. Polymerization was performed using a one-pot method in an aqueous solution in the presence of polyvinyl alcohol (PVA). The structural and thermal properties of PVA/poly(IA-co-AMPS) were studied using Fourier transform infrared, differential scanning calorimetry, and thermogravimetry analysis. PVA formed strong hydrogen bonds with hydrophilic functional groups in the SAP network to improve the gel strength and thermal stability of the SAP. A PVA content of 6 wt% increased the centrifuge retention capacity and absorbency under load of the SAP to 60.1 and 16.4 g/g, respectively. Owing to the less salt-sensitive hydroxyl groups of PVA, semi-IPN SAP showed higher absorption (up to 26.3%) in an aqueous salt solution. The resulting SAP has a very low concentration of residual monomers (167.4 ppm). Experimental results suggest that PVA/poly(IA-co-AMPS) is an eco-friendly SAP with excellent absorption properties, making it suitable for application in personal care products.