UNIQUAC法预报N-异丙基丙烯酰胺凝胶在乙醇水溶液中的溶胀行为

Predicting the swelling behavior of N-isopropylacrylamide gels in ethanol-water mixtures with UNIQUAC

以N-异丙基丙烯酰胺(NIPAAm)为单体,合成了NIPAAm均聚凝胶。研究了25℃时它们在乙醇水溶液中的溶胀平衡。实验发现;当乙醇浓度约为12％时,少量乙醇的进一步加入将使溶涨的凝胶突然剧烈收缩,表明NIPAAm凝胶在乙醇水溶液中有不连续体积相变。随着乙醇不断加入,凝胶又重新溶涨。结合“自由体积”概念,利用UNIQUAC模型的关联和预报了NIPAAm凝胶在乙醇-水溶液中的这种溶涨行为。

N - isopropylacrylamide ( NIPAAm) was used to synthesize NIPAAm homopolymer. The swelling behavior of gel was investigated in aqueous solution of ethanol with concentration ranging from 0 to 100 mass-percentage at 25C. The results demonstrated that the swollen gel in water shrank first with the addition of a small amount of ethanol and then reswelled with further addition of ethanol showing the gel underwent a discontinuous volume phase transition in aqueous solution at ethanol. A thermodynamic model based on the UNIQUAC with the 'free-volume' contribution was applied to correlate anr' predict the swelling behavior of the N - isopropylacrylamide gels in ethanol-water mixture. The results correlated and predicted by the model are consist good with the experimental data.