Departament d'Enginyeria Química, Universitat Rovira i Virgili, Av. Països Catalans, 26, E-43007 Tarragona, Spain.
Langmuir. 2010 Sep 21;26(18):14821-9. doi: 10.1021/la101809r.
Novel composite asymmetrical membranes based on poly(vinyl alcohol)-co-ethylene (EVAL) as the host material and new polyethers that contain azobenzene moieties in the side chain were prepared by dry-cast phase inversion after dissolving the azo polymers in tetrahydrofuran and EVAL in dimethylsulfoxide and subsequently mixing the resulting solutions. By taking advantage of the proper temperature variation in the oven used for solvent evaporation, asymmetrical membranes that exhibited a dense, crystalline layer on the bottom and a porous, mainly amorphous layer on the top were obtained. Remarkable changes in the surface morphology and the contact angle with water were observed on the top surfaces of the composite membranes. This was ascribed not only to the enhanced concentration of azo polymer on the top surface but mostly to a conformational change in EVAL induced by the photoisomerization of the guest azo groups, as shown by HRMAS (1)H NMR. The morphological and structural changes in EVAL could be reversed on exposing the membrane to visible light for 24 h.
基于聚（乙烯醇）-共-乙烯（EVAL）作为主体材料和含有偶氮苯侧基的新型聚醚的新型复合不对称膜，是通过将偶氮聚合物溶解在四氢呋喃中和 EVAL 溶解在二甲基亚砜中，然后混合所得溶液，再通过在用于溶剂蒸发的烘箱中利用适当的温度变化，采用干铸相转化法制备的。在底部形成致密的结晶层，在顶部形成多孔的主要无定形层，从而获得具有不对称结构的膜。在复合膜的顶表面观察到表面形貌和与水的接触角发生了显著变化。这不仅归因于顶表面上偶氮聚合物浓度的增加，而且主要归因于客体偶氮基团的光致异构化所引起的 EVAL 的构象变化，这一点通过高分辨率魔角旋转（1）H NMR 得到了证实。通过将膜暴露于可见光下 24 小时，可以使 EVAL 中的形态和结构变化得到逆转。
