Preparation and characterization of a novel superabsorbent of konjac glucomannan-poly(acrylic acid) with trimethylolpropane trimethacrylate cross-linker

Abstract

A novel konjac glucomannan-acrylic acid superabsorbent (KGMP) was prepared by the solution polymerization of partially neutralized acrylic acid (AA) onto konjac glucomannan (KGM) using potassium persulfate (KPS) as a free radical initiator and trimethylolpropane trimethacrylate (TPTA) as a crosslinking agent. Effects of the content of TPTA on the water absorption in buffer solutions of different pH were investigated. The results showed that the swelling ratio exhibited the largest value at pH 7.4 due to electrical interaction. There was an appropriate content of TPTA in the KGMP that made the swelling ratio reach its maximum. Swelling kinetics of the KGMP at pH 7.4 was also studied. The swelling processes of the polymers can be fitted to the first-order reaction kinetics. The structure, morphology and thermal stability of KGMP were further characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), using KGM as reference. Results indicated that a successful graft polymerization reaction and excellent miscibility occurred between KGM and AA and the content of TPTA affected the orderliness of KGMP.