客体小分子在超分子有机凝胶体系中的扩散释放

Diffusion and Release of the Guest Molecules in Supramolecular Organogel

采用二(4-硬脂酰胺基苯基)甲烷(BSAPM)为凝胶剂制备了含有小分子水杨酸和若丹明B的1,1,2-三氯乙烷(TCE)超分子有机凝胶.以超分子有机凝胶作为主体,客体小分子水杨酸和若丹明B可轻微降低超分子有机凝胶的相转变温度(TGS).用紫外-可见光度法研究了超分子凝胶中两种客体小分子在静态下的扩散释放.结果表明其释放率随凝胶剂浓度的增加而降低.客体小分子的体积大小对其释放有明显的影响,分子体积较大的若丹明B的释放率低于分子体积较小的水杨酸.另外,若丹明B的扩散系数也低于水杨酸,且随凝胶剂浓度的增加,这种趋势更为明显.两种客体分子的累积释放率与时间的平方根成良好的线性关系,符合Higuchi方程,属扩散控制的Fickian释放机理.

Bis（4-stearamidophenyl）methane （BSAPM） was used as a gelator for preparation of 1,1,2-trichloroethane （TCE） supramolecular organogels. The existence of salicylic acid and rhodamine B as the guest molecules led to the slight decrease of gel-sol phase transition temperatures （Tcs） of the organogels. The diffusion and release of the guest molecules in the organogels were investigated by using UV-vis spectroscopy. The results indicated that release ratios of the guest molecules decreased with the increase of the gelator concentration. Wherein, the release ratios of rhodamine B were less than those of salicylic acid, which could be attributed to the larger molecular size of rhodamine B. In addition, the diffusion coefficients of rhodamine B were also less than those of salicylic acid. This trend was clearer with the increase of BSAPM concentration. The investigation indicated that the diffusion and release behavior of the guest molecules in the self-assembled organogel followed the Higuchi equation and diffusion-controlled mechanism of Fickian model.