Preparation and Property of Poly(N-isopropylacrylamide) (PNIPAAm)/Clay/Linear Polyacrylamide (PAAm) Nanocomposite Hydrogels

Abstract

In this study, a linear polyacrylamide (PAAm) with an average viscosimetric molecular weight 3.97 × 103 kg mol−1 was added to the prereaction solution for the preparation of poly(N-isopropylacrylamide) (PNIPAAm)/clay nanocomposite hydrogels. The effects of the linear PAAm on the optical transparency and tensile property of the resulting PNIPAAm/clay/linear PAAm hydrogels were systematically investigated. The results revealed that the optical transparency and mechanical tensile properties of the resultant hydrogels strongly depended on the linear PAAm content. In particular, 5 wt% loading of linear PAAm led to almost fivefold decreases of transmittance at 25°C and a onefold increase of the tensile elongation at break. These characteristic changes were explained by a typical interpenetrating microstructure, which was formed by PNIPAAm due to the incorporation of linear PAAm in the PNIPAAm/clay network. The dynamic rheological test and infrared spectroscopy analysis on the mixed solutions consisting of linear PAAm and clay platelets further confirmed the interaction.