A novel hydrogel-dispersed composite membrane of poly(N-isopropylacrylamide) in a gelatin matrix and its thermally actuated permeation of 4-acetamidophen

A novel hydrogel-dispersed composite membrane was fabricated with poly (N-isopropylamide) (p(NIPAAm)) and crosslinked gelatin, and its thermally actuated transport characteristics of 4-acetamidophen were investigated in a diffusion cell. The composite membrane was prepared by in situ polymerization of entrapped monomers in vacant spaces of gelatin matrix. The vacant spaces in gelatin matrix were formed by dissolving the dispersed particles of calcium carbonate in gelatin. The flux of 4-acetamidophen through the composite membrane drastically increases when the temperature increases from 25 to 40 degrees C, while it does not through pure p(NIPAAm) membrane. The flux decreases above the lower critical solution temperature (LCST) of p(NIPAAm), Such a permeation behavior, opposite to those of pure p(NIPAAm), was not completely understood. However, it is believed that p(NIPAAm) in the composite membrane responded to temperature as ifa gate valve were operating. Therefore, the permeation characteristics were regulated by the swelling and shrinking of p(NIPAAm) hydrogel particles in microchannels in the hydrogel-dispersed gelatin membrane.