含氟嵌段共聚物/ SiO2杂化粒子构筑耐久性透明超疏水保护层的研究

An important approach to achieve durable and efficient protection of outdoor immovable sandstone heritage (OISH) against the intake of water is to create a durable, colorless and transparent superhydrophobic coating with self-cleaning property on the OISH surface. However, the key problem in fabricating such superhydrophobic coating is how to simultaneously creat a durable low surface-energy surface and a microstructure fulfilling the demand for wear resistance, transparency, superhydrophobicity and self-cleaning by a simple and applicable way. In this project, we firstly focus on the controlled preparation of core-shell fluorinated block copolymer/silica hybrid nanoparticles with silica enriched in core and fluorinated groups enriched in shell via a hydrophobic-interaction-driven micelle templating approach. When one-step spray-coating the hybrid nanoparticles, a durable low surface-energy surface is created by the surface enrichment of fluorinated groups. Importantly, the surface microstructure from the self-assembly of hybrid nanoparticles is manipulated by varying spray-coating parameters, nanoparticle composition, size, dispersants, etc. Finally, a durable, colorless and transparent superhydrophobic coating with self-cleaning property is obtained by revealing the effect of surface microstructure on wear resistance, transparency, superhydrophobicity and self-cleaning property. When treating the OISH surface with hybrid nanoparticles by one-step spray casting process, protective efficiency and mechanism will be further confirmed. Our research results will have important guiding significance in the development of durable water repellent coatings for the protection of OISH.

在室外不可移动砂岩文物（OISH）表面构筑耐久无色透明的超疏水自清洁保护层是实现对OISH持久高效防水的重要途径。此种保护层构筑的难点是如何通过简单适用的方法使其表面同时具有耐久的低表面能物质和满足耐磨、透明和超疏水自清洁性质要求的微观结构。鉴于此，本项目提出首先采用基于静电作用的胶束模板法，可控制备核层富集SiO2，壳层富集含氟组分的含氟嵌段共聚物/ SiO2杂化纳米粒子；再将其采用一步法喷涂成膜，利用含氟组分的表面富集行为构建耐久性低表面能表面，同时重点利用杂化粒子在组成、尺寸、分散剂和喷涂工艺参数等改变下自组装方式的不同调控表面微观结构；通过揭示微观结构对薄膜耐磨性、透明性和超疏水自清洁性的影响规律，构筑出耐久无色透明的超疏水自清洁薄膜；最后将杂化粒子喷涂于OISH表面，确定所形成保护层的保护功能及功能实现的机理。研究结果对发展耐久性OISH防水保护材料具有重要指导意义。

超疏水涂层具有优异的自清洁性质，在科学研究和生产、生活等诸多领域具有广泛的应用前景。但当其表面被油污染后，疏水性能会急剧下降。因此，应赋予超疏水涂层超疏油性质，即使水滴或油滴均易在涂层表面滚动或滑动，而不留下任何痕迹。由此获得的超双疏涂层，在超润湿领域备受关注。尽管目前已通过控制表面化学组成和多尺度微纳米结构，或通过构筑多孔层，然后向其中灌入低表面能液体，以及通过接枝低表面能液态聚合物以形成聚合物刷获得了超双疏涂层。但是，每种方法都潜存着弱点和缺陷，无法使涂层在疏水、疏油、透明和耐磨性能方面兼得，从而极大地限制了超双疏表面的实际应用。本项目首先利用多顶状SiO2提供凹角结构，氟硅烷偶联剂降低表面能，含氟丙烯酸酯嵌段共聚物提供黏结力，构筑了一种耐久型超疏水高疏油涂层。该涂层对水的静态接触角在160± 2°~165± 2°之间，滚动角在7°~9°之间，且水滴可在涂层表面弹跳；对油（十六烷）的静态接触角在143± 2°~150± 2°之间。选用5 %wt的NaOH水溶液和5 %wt的HCl水溶液先后在1000 r/min的搅拌速度下，冲刷该涂层24h后，涂层表面完整无脱落，且表面对水和十六烷的润湿行为几乎不变。为了进一步获得无色透明型超双疏涂层，本项目还制备了含氟单元末端功能化的PMMA聚合物DFHM7-ef-MMA305。DFHM7-ef-MMA305在THF中成膜后，表面光滑透明；且无明显的相分离，是一种均质表面。尽管水和十六烷在其表面的静态接触角不大（水的接触角为108± 2°，十六烷的接触角为53± 2°），但水和十六烷均可在其表面自由滑动。水的滑动角为33± 2°，十六烷的滑动角为13± 2°。研究还发现，当在THF中加入DFHM7-ef-MMA305的不良溶剂MeOH，并改变VMeOH : VTHF 从0.43:2至2:2时，表面仍具有超双疏性质。