N-异丙基丙烯酰胺温度敏感性水凝胶相转变动力学研究及其应用

A STUDY ON PHASE TRANSITION KINETICS OF TEMPERATURE-SENSITIVE N-ISOPROPYLACRY- LAMIDE HYDROGELS AND ITS APPLICATION

研究指出表观二级动力学方程可以很好地描述N-异丙基丙烯酰胺水凝胶的溶胀和消溶胀动力学.即溶胀动力学方程为dR/dt=k_1(R_e-R)~2,消溶胀动力学方程为-dR/dt=k_c(R-R_e)~2.把这种水凝胶用于分离高分子水溶液时可引入“单位溶张比分离循环的合理时耗”这样一个参量.它根据溶胀和消溶胀过程中的起始溶胀比、平衡溶胀比、表观溶胀动力学常数和表观消溶胀动力学常数求出.具体公式为△t_1(T_s,T_c)=2/[R_c(T_s)-R_0(T_s)]~2k_s(T_s)+15/[R_0(T_c)- R_s(T_c)]~2k_c(T_c)^(1/2)在理想情况下,分离过程的“总合理时耗”与△t_1成正比,比例系数为分离过程中的除水总量与干凝胶用量的比值,即△t_r=W_W/W_G·△t_1.当根据二个动力学方程求得的总时耗计算值处于(0.9△t_r,1.1△t_r)范围内时,表明所选干凝胶用量和循环溶胀比区段均合适.

The phase transition kinetics of temperature-sensitive N-isopropylacrylamide hydrogel was investigated. It was indicated that the apparent second order kinetic equations describe its swelling and collapse behavior quite well. Its swelling kineticequation is (dR)/(dt)= ks(Rg- R)2 and the collapse one is- (dR)/(dt)= (kc(R-Rc)2. A para-meter of 'reasonable time of separating circle per swelling ratio' was introduced for describing the separating behavior of polymer water solution. It can be calculated from initial swelling ratio, equilibrium swelling ratio, swelling kinetic constant and collapse kinetic constant. The equation isAt the ideal case, total time for separation is proportional to @t1. The ratio factor is equal to the total water weight separated divided by the dry hydrogel weight, thatis. When the calculated value of the total time based on the two ki-netic equations was located into the region of (0.9△tr,1.1△tr), it means that the dry hydrogel weight chosen and the circular swelling ratio region chosen are reasonable.