Rapid Shrinking of Porous Hydrogel Prepared by Ice Templating
To control and maximize the shrinking rates of thermo-sensitive organic-inorganic (O-I) hybrid gels, microporous structure of gels could be controlled by ice-templating. Water-swollen gels easily became porous after freezing. Applying the freezing method effectively accelerate the shrinking rates of the poly(N-isopropylacrylamide), polyNIPA-based O-I hybrid gels by two different ways. One is the interpenetrating network with polyNIPA and polysiloxane. The other is the copolymer network of NIPA and a vinyl monomer possessing the trimethoxysilane, of which crosslinking was carried out by sol-gel reaction. Their thermally-triggered shrinking kinetics was investigated by measuring the weight change of gels. Shrinking coefficients (D) were determined by fitting the shrinking data with the Fick’s model. The coefficients after applying the freezing method increased to approximately 10-3 cm2s-1 while those before freezing were on the order of 10-5 - 10-6 cm2s-1.
Pietro VINCENZINI and Giuseppe D'ARRIGO
E. Umebayashi et al., "Rapid Shrinking of Porous Hydrogel Prepared by Ice Templating", Advances in Science and Technology, Vol. 54, pp. 103-108, 2008