Preparation of amphoteric nanocomposite hydrogel under supercritical carbon dioxide and its fast-swelling behaviours

Abstract

Supercritical carbon dioxide (scCO2) has been widely used in preparation of nanocomposite materials. However, so far there has been no report on preparation of nanocomposite hydrogels by intercalation of hydrophilic monomers into clay under scCO2 condition. In this paper, the fast-swelling amphoteric nanocomposite hydrogels were prepared via the free radical polymerisation of acrylic acid (AA) and N-[3-(dimethylamino) propyl] methacrylamide (DMAPMA) in the presence of clay under scCO2 condition. The composition of the hydrogel was determined by element analysis and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results illustrated that the clay layers became disordered after intercalation by AA and DMAPMA under scCO2 condition. The swelling kinetics and deswelling characteristics were tested. The results indicated that the hydrogels presented marked swelling rate in deionised or saline water and fast deswelling rate in alcoholic solution.