基于液晶基元锚固的短链氟烷基聚合物构效关系研究

Since long-chain perfluoroalkyl materials are facing the problem of toxicity and bioaccumulation, it has been a hot research topic to develop environment friendly long-chain perfluoroalkyl substitutes with stable surface properties in the current fluorine-containing materials. Recently, many researchers use biodegradable short-chain fluoroalkyls (C≤6) to build low surface energy materials, but the short-chain fluoroalkyls have the problem of rearrangement of molecular structure in contact with polar liquids, making the liquid repellency far less than the long-chain fluoroalkyl materials. Our project intends to anchor a plurality of short-chain fluoroalkyls to the end of mesogenic units, improving the shielding effect of short-chain fluoroalkyls. At the same time, with the self-assembly of mesogenic units, the short-chain fluoroalkyls are induced to form an ordered arrangement on the material surface and form a crystalline phase, which prevents the rearrangement of short-chain fluoroalkyls, and provides the liquid repellency comparable to long-chain fluoroalkyl materials. By studying the crystalline state and the stability of the clustered short-chain fluoroalkyls, the shielding effect, and the relationships between the liquid repellency and material structure, our project will provide new ideas for preparing short-chain fluoroalkyl materials with stable low surface energy and lay the foundation for the replacement of long-chain fluoroalkyl materials by short-chain fluoroalkyls.

针对长链全氟烷基材料的毒性和生物累积性问题，开发具有稳定表面性能且环境友好的长链全氟烷基替代品已成为含氟材料的研究热点。近年来，许多研究者采用可降解的短链氟烷基（C≤6）来构筑低表面能材料，但因短链氟烷基在接触极性液体时发生分子构象重排，使其拒液效果远不如长链氟烷基材料。因此，本项目拟将空间尺寸与液晶基元相匹配的多个短链氟烷基锚固于液晶基元末端，由此提高短链氟烷基的屏蔽效应，同时借助液晶基元片段间的自组装趋势，诱导短链氟烷基在材料表面进行有序排列并形成结晶相，防止短链氟烷基的构象重排，提供媲美长链氟烷基材料的拒液性能。通过研究末端簇集态短链氟烷基的结晶状态及其稳定性，以及由此产生的屏蔽效应、拒液性能与材料结构之间的关系，本项目将为制备稳定低表面能短链氟烷基材料提供新思路，并为短链氟烷基材料替代长链氟烷基材料奠定基础。

长链全氟烷基化合物（CnF2n+1，n≥8）由于在自然环境中氧化降解生成具有生物累积性和毒性的全氟羧酸或全氟磺酰化物而被禁止使用。而短链氟烷基聚合物形成的氟膜在长时间接触极性液体后，表面的短链氟烷基存在构象重排现象，导致氟屏蔽失效、氟膜的拒液性能急剧下降。因此，如何实现短链氟烷基聚合物的持久拒液性能是亟需解决的难题。本项目针对液晶基元对聚合物中短链氟烷基侧链的定向诱导作用以及材料结构与表面性能之间的关系进行了研究。具体研究结果如下：（1）制备了通过苯环锚固的短链氟烷基聚丙烯酸酯，其交联膜在与水滴接触20分钟后，接触角仅下降4.6°，实现了具有持久拒水性含氟聚合物的研制；（2）构建了4种苯环锚固短链氟烷基为侧链，硅氧烷为主链的含氟聚硅氧烷，乳化后应用于棉织物的后整理，成功获得了具有稳定拒液性、热稳定性和增深效应的多功能化棉织物；（3）获得了4种具有优异耐洗性能的自交联氟化聚丙烯酸酯膜；（4）制备了一种全新的苯酯基锚固短链氟烷基侧链的含氟聚合物，其苯环中的π-π共轭体系为氟烷基提供了稳定的分子构象，使其具有稳定的拒液性能；（5）建立了苯基、联苯基、苯酯基等刚性基团诱导短链氟烷基定向以及由此获得低表面能材料的有效方法。本项目为具有稳定低表面能的短链氟烷基聚合物分子结构设计提供了实验及理论基础。