IPAAm凝胶在丙酮水溶液中溶胀行为的关联与预报

基于Maurer和Prausnitz的凝胶相平衡条件，建立了凝胶的溶胀模型.模型假设凝胶是以凝胶组分及凝胶吸收的溶液为核心，以弹性半渗透膜为壳的复合体.并采用UNIQUAC方程计算凝胶相及与之共存液相的Gibbs过剩自由能，采用“phantomnetwork”理论计算凝胶的弹性自由能，采用“自由体积”计算分子的尺度效应.同时以N-异丙基丙烯酰胺（IPAAm）为单体合成了IPAAm凝胶.研究了25 ℃时IPAAm凝胶在丙酮水溶液中的溶胀行为，并测定了丙酮在胶体相和与之共存液相中的分配，以检验模型的关联与预报能力.结果表明,模型预报的单体总量和交联剂浓度对凝胶溶胀的影响与实验符合得很好.而且凝胶溶胀时，能很好地预测丙酮在两相中的分配,表明模型具有很好的关联和预报能力.

Correlation and Prediction of Swelling Behavior of N-isopropyl-acrylamide Based Hydrogels in Aqueous Solution of Acetone

Based on the phase equilibrium conditions for systems containing gels given by Maurer and Prausnitz, a model to correlate and predict the swelling behaviors of hydrogels in aqueous organic solutions is proposed. In the model, gel is considered as a combination of a shell of an elastic semipermeable membrane and a core of a fluid phase. The fluid core consists of only the network building materials and other components that are able to partition in gel phase and surrounding coexisting liquid phase, and is enveloped by the membrane shell. The excess Gibbs energies of the gel phase and the surrounding coexisting fluid phase are calculated using UNIQUAC equation, the elastic properties of polymer network are described by the " phantom network" theory, and the additional differences in the size of the species are taken into account by " free- volume" contribution. To test the model, a series of N- isopropylacrylamide gels, using N,N′- methylene diacrylamide as the crosslinker, are synthesized by free radical polymerization under nitrogen atmosphere. The swelling experiments are conducted in aqueous solution of acetone at 25 ℃ . The results show that the increases of swelling capacity of the gels with decreasing amount of crosslinker and total mass fraction of polymerizable materials predicted by the model are in good agreement with the experimental data. Moreover, the model also predicts no difference of acetone concentration in the gel phase and the coexisting liquid phase, as long as the gel is in a swollen state. However, in the region where the swelling degree of the gel is rather small there is a small enrichment of acetone in the gel phase. All these show the potential of the model to correlate and predict the swelling behaviors of hydrogels in aqueous organic solutions.