Preparation and absorption studies of poly(acrylic acid-co-2-acrylamide-2-methyl-1-propane sulfonic acid)/graphene oxide superabsorbent composite

A new superabsorbent composite poly(acrylic acid-co-2-acrylamido-2-methyl-1-propane sulfonic acid)/graphene oxide was synthesized by solution polymerization of acrylic acid and 2-acrylamido-2-methyl-1-propane sulfonic acid in the presence of graphene oxide (GO) using ammonium persulfate as an initiator and N,N-methylene bisacrylamide as a cross-linker. The composite was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, high-resolution scanning electron microscope, scanning electron microscope-energy-dispersive spectroscopy, thermogravimetric analysis and differential scanning calorimetry. It indicated that GO served as a cross-linker during polymerization. The swelling behavior of the composite in deionized water and 0.9% NaCl solution was investigated in detail. It showed that there was a remarkable increment of absorption after the incorporation of GO. The absorption capacities of water and saline increased from 322 and 59g/g to 768 and 115g/g, respectively, as the content of GO increased from 0 to 5wt%. The composite exhibit good water retention performances. The movement of both hydrate and bound water in the composite was greatly blocked due to the steric hindrance and attraction of the hydrophilic groups. Water retention rate was 65.2 and 34.2% after drying for 6h at 60 and 100 degrees C, respectively.