Amphoteric nanocomposite hydrogels (NC gels) were synthesized by in situ copolymerization of acrylic acid (AA) and N [-3(dimethylamino)propyl] methacrylamide (DMAPMA) in an aqueous dispersion of laponite XLG. Mechanical analyses demonstrated that this type of hydrogels had a combination of high tensile strength and excellent stretchability. The tensile strength was increased by 5 times up to 316 kPa when the laponite content was increased from 0.1 wt% to 20 wt%, and a maximum fracture strain of 2,317% was achieved for hydrogels containing 3 wt% laponite. Additionally, the marked improvements in strength were achieved with minimal sacrifice of the tensibility. This work provided a continuation to previous efforts of the preparation and properties of ionic NC gels. POLYM. COMPOS., 36:538-544, 2015.

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Supercritical carbon dioxide (scCO 2) 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 scCO 2 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 scCO 2 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 scCO 2 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.

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