Preparation and properties of chitosan-poly(N-isopropylacrylamide) full-IPN hydrogels

A new kind of full-IPN chitosan/poly(N-isopropylacrylamide) (CS/PNIPAM) hydrogels was prepared by chemical combination of methylene bis-acrylamide (MBAM) cross-linked PNIPAM network with formaldehyde (HCHO) cross-linked CS network It was demonstrated that the properties of the gels, including the extractability of PNIPAM within it, the phase transition behavior, the swelling dynamics in aqueous phase, the swelling behavior in ethanol/water mixtures and even the microstructure are quite different from those of the semi-IPN CS/PNIPAM hydrogels, in which PNIPAM was simply embedded. Like the semi-IPN CS/PNIPAM hydrogels, however, the new gel is also temperature sensitive, that is the gel is transparent below 30 degreesC, whereas opaque above the temperature. It is expected that the finding of the new smart hydrogels may find some uses in separation science and in the design and preparation of new soft machines. (C) 2001 Elsevier Science B.V. All rights reserved.