含硫(VI)长杂链替代长碳链全氟烷基的基础研究

It is well known that polymers with perfluoroalkyl long carbon-chains can provide excellent liquid repellency. However, the perfluoroalkyl long carbon-chains with more than eight carbon atoms will degrade to form perfluorooctanesulfonate (PFOS), which is hard to decompose and shows extreme stability, bioaccumulation and toxicity. Therefore, these perfluoroalkyl long carbon-chains and derivatives will be banned in the future. This project proposes to embed the tetrafluorosulfunyl (-SF4-) into the perfluoroalkyl and construct sulfur(VI)-containing perfluorosulfanyl long hetero-chain. Using the perfluorosulfanyl long hetero-chain as substituted groups, fluorine containing materials with extreme low surface free energy can be obtained. The wide-angle X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and other modern analysis methods can be applied to confirm the rigidity and crystallinity of the perfluorosulfanyl long hetero-chains, and furthermore, to verify the stable conformation of the perfluorosulfanyl film surface. These structural features can offer excellent liquid repellency. In addition, introducing of sulfur atom into perfluoroalkyl can overcome the non-biodegradable and bio-toxicity defects of perfluoroalkyl long carbon-chains. The surface structure of fluorine-containing films, together with the gather and assemble of perfluorosulfanyl long hetero-chains on the film surface will be analyzed, which will help to find the relationship between the structure and properties, and to build the new methods and theories of how to reduce the surface free energy with perfluorosulfanyl long hetero-chains effectively. The biological toxicity tests of perfluorosulfanyl long hetero-chain derivatives and their decomposition products can establish a toxicological database of fluorine-containing compounds, which will set up the theoretical foundation of substitution for the perfluoroalkyl long carbon-chains and designing or preparing environment friendly fluorine containing materials.

长碳链全氟烷基可赋予聚合物非常优异的拒液性能，但长度≥8的全氟碳链降解至全氟辛烷羧酸（PFOS）再难分解，且具有累积性和生物毒性，因此面临禁用。本项目提出在全氟烷基中嵌入四氟硫甲撑（-SF4-），由含硫（VI）长杂链全氟烷基提供极低表面能；同时，长杂链全氟烷基保持了锯齿形刚性结构，其结晶性可赋予全氟烷基表面膜构象稳定性。以广角X-射线衍射（XRD）和X-射线光电子能谱（XPS）等现代表征方法可探索长杂链全氟烷基提供优异拒液性能的这一结构本质。分析氟膜表面结构还可了解长杂链全氟烷基的聚集状态，得出结构性能关系规律，建立由长杂链全氟烷基取代基有效降低材料表面能的新方法和新理论。长杂链中硫（VI）原子的引入可望克服长碳链全氟烷基难降解和生物毒性的缺陷。对长杂链全氟烷基衍生物及其分解产物的生物毒性测试还可建立含氟化合物的毒理数据库，并为替代长碳链全氟烷基、设计和制备环境友好的含氟材料奠定理论基础。

本项目主要研究含硫(VI)长杂链全氟烷基（-SF4-Rf）及含氟聚合物材料的合成及其结构性能关系：（1）设计合成了含硫(VI)长杂链全氟烷基不饱和单体、聚合物，及含硫(VI)长杂链全氟烷基硅烷，将其应用于纤维表面处理时提供低表面能防护，分析了含硫(VI)长杂链全氟烷基结构与整理织物表面性能之间关系，实现了具有优异超疏水功能的纤维表面处理；通过对比研究长碳链全氟烷基与含硫(VI)长杂链全氟烷基的光降解性，探索了C-S(F4)杂键在长杂链全氟烷基降解过程中可提供化学弱键的机制。研究证实了含-SF4-的新型长杂链全氟烷基结构同时可提供优异表面性能和拒液功能，又易光降解的科学事实，研究成果可望为克服碳链全氟辛基（如PFOS）材料的难降解、具累积毒性的缺陷，开创具有优异表面性能的环境友好型氟材料新方向。（2）利用易于形成聚合物结晶的含氟卡宾聚合物和氟烷基苯基自由基聚合物，由含氟单体对纤维接枝改性，在纤维表面化学改性时原位生成“糙化”物理形貌，创新性地在织物/纤维表面原位引入了超拒液所需的两个条件，即可控的表面粗糙物理结构和低表面能物质。系统研究了织物/纤维表面氟聚合物防护层的化学/物理结构协同对其拒液功能的影响关系，得出了纤维表面结构与超浸润性关系规律。氟聚合物接枝改性纤维原位“糙化”的研究成果为精细构筑氟材料表面涂层结构，最大限度发挥其拒液功能指明了方向，也为提升目前传统的含氟整理剂拒液功能，替代长碳链全氟烷基奠定了良好的理论基础。