A temperature-sensitive composite membranes of poly(N-isopropylacrylamide) hydrogel embedded in gelatin matrix were synthesized and permeation of 4-acetamidophenol through the membrane was investigated.
Poly(NIPAAm) exhibited volume phase transition from hydrophilic to hydrophobic state about 36℃. The crosslinked gelatin matrix was cast with calcium carbonate, pores could be created in crosslinked gelatin matrix by calcium carbonate elimination, and poly(NIPAAm) hydrogels could be entrapped into the pores in the gelatin matrix by polymerizing monomer solution. Depending on the amount of calcium carbonate, maximum permeation through the composite membrane existed.
The optical transmittance change near the phase transition temperature of poly(NIPAAm) hydrogel in composite membrane verified the entrapment of poly(NIPAAm) hydrogel particle.
The composite membrane showed temperature-sensitive permeability change. When the surrounding temperature was higher than its transition temperature, the permeation through the membrane increased, but when the surrounding temperature was lower than its transition temperature, the permeation through the membrane decreased.
The effect of degree of crosslinking on permeation behavior was not apparent in composite membranes, but difference of permeation amount between under and above LCST through the membrane decreased as degree of crosslinking increased.
The transition temperature could be controlled by copolymerization with sodium acrylate, but the permeation with composite membrane using sodium acrylate has not shown the shift of transition temperature.
