Control of ionic transport vector using a temperature-responsive ionic gel membranes

采用n -异丙基丙烯酰胺与聚乙烯醇（PVA）接枝共聚物、聚阴离子与PVA的DMSO溶液浇铸法制备了温度响应型带电膜。得到的膜在0.025wt%戊二醛和0.1 N HCl的水溶液中，50℃交联5min。我们测量了由膜和KCl溶液组成的透析系统在10℃和50℃温度下的膜电位，得到了电荷密度。随着温度的逐步变化，10 min内电荷密度在0.07 mol dm^<-3>和0.28 mol dm^<-3>两个值之间呈可逆增减趋势。在膜透析体系和混合KCl-CaCl_2溶液中，低浓度室的Ca^<2+ b>离子浓度随温度的逐步变化随时间呈可逆的增减趋势。这意味着Ca^<2+>离子在10℃时从高浓度室扩散到低浓度室，并在50℃时逆浓度梯度输送。综上所述，系统中低浓度室中二价离子的浓度在温度高于最低温度时降低，低于最低温度时升高。这意味着该系统具有关于多价离子浓度的负反馈机制。因此，温度响应带电膜将应用于自我调节系统，可以根据温度调节系统中特定溶质的浓度，例如，具有稳态机制的“智能”药物输送和血液透析系统。

Temperature-responsive charged membranes were prepared by casting DMSO solution of graft copolymer of N-isopropylacrylamide and poly (vinyl alcohol)(PVA), polyanion and PVA.The membrane obtained was crosslinked in an aqueous solution of 0.025wt% glutaraldehyde and 0.1 N HCl at 5O℃ for 5 min. We measured the membrane potential in a dialysis system consisting of the membrane and KCl solutions to obtain the charge density at the temperatures : 10℃ and 50℃. The charge density increases and decreases reversibly between the two values : 0.07 mol dm^<-3> and 0.28 mol dm^<-3> within 10 min in response to stepwise changes in the temperature.In the dialysis system of the membrane and mixed KCl-CaCl_2 solutions, the concentration of Ca^<2+> ion at the low-concentration chambers increases and decreases reversibly with time in response to the stepwise changes in the temperature. This means that Ca^<2+> ions diffuse from the high-concentration chambers to the low concentration chambers at 10℃, and are transported against their concentration gradient at 50℃.In conclusion, the concentration of the bivalent ions in the low-concentration chambers in the system decreases at a temperature above the LCST and increases below the LCST.This means that the system has a negative feedback mechanism with regard to the concentration of multi-valent ions. Therefore, the temperature-responsive charged membrane will be applied for self-regulating systems which can adjust the concentration of specific solutes in the systems in response to temperature, for examples, 'intelligent' drug delivery and hemodialysis systems which have a homeostasis mechanism.