微胶囊共混法构筑自修复型超疏水涂层

Preparation and application of superhydrophobic materials have drawn more and more attention due to its special advantage in some application fields, such as reducing flow resistance in microfluidic channels,separation of oil/water and self-cleaning surface.Further study revealed that the wettability of a surface was governed mainly by its chemical composition and geometrical structure.However, most of the superhydrophobic coatings suffer from low durability. Once the surface is mechanically damaged such as scratch, it will lose its superhydrophobic property. Therefore, development of common coatings with self-healing superhydrophobic properties is promising task.In this study, fluoro-monomer(perfluorooctyl trimethoxysilane, fluorinated isocyanate) is loaded in urea-formaldehyde microcapsules, which are blended with epoxy or polyurethane, resulting in superhydrophobic coating with self-healing property.The fluoride-segments spontaneously migrate to the outside of capsule shell,spread out into air,while trimethoxysilane segment or isocyanate group react with hydroxy group on the surface of capsule shell. Combining with hierarchical structure of micrcapsules, superhydrophobic property is achieved; if scratched, the surface recovers its superhydrophobic properties due to the migration of fluoro-monomer to the newly formed surface，which are polymerized product of monomer released from broken microcapsules. This study not only expand the application field of self-healing superhydrophobic coating, but also provide a theoretical basis for preparation of other self-healing functional coatings.

超疏水表面在金属减阻、油水分离以及自清洁等方面均显示出其独有的优势，但其表面结构容易被破坏，从而丧失超疏水性能。因此，对自修复型超疏水表面的研究势在必行。现有研究大多需对基体材料的组成及结构进行精细设计，对普适性聚合物的自修复型超疏水表面研究不足。本申请拟采用具备微-纳结构的脲醛树脂微胶囊装载氟化单体（全氟辛基三甲氧基硅烷、氟化多异氰酸酯），通过共混法与环氧树脂或聚氨酯共混。氟化单体中的全氟链段会缓慢向微胶囊外表面迁移、向空气界面伸展；而三甲氧基硅烷/异氰酸酯基团则与脲醛树脂微胶囊表面的羟基反应，使全氟组分接枝于微-纳结构表面，得到超疏水涂层。当发生刮蹭或磨损时，微胶囊释放氟化单体，聚合修复损伤部分，从而实现表面超疏水性能的恢复。本研究能拓展自修复型超疏水涂层的应用领域，也能为其他自修复型功能涂层的制备提供理论参考。

超疏水涂层具有特殊的浸润性能而备受关注，但其表面结构容易被破坏，从而丧失超疏水性能。本项目采用三聚氰胺甲醛树脂微胶囊装载1H, 1H, 2H, 2H-全氟十二烷基三乙氧基硅烷单体（G617），与聚氨酯（PU）共混制备复合涂层。利用微胶囊粒径及表面粗糙度可调节的特征，构筑复合涂层的多级微-纳结构。同时，氟化单体中的全氟链段会自发向微胶囊外表面迁移、向空气界面伸展，以降低材料表面能。两方面因素共同作用，使得PU/G617微胶囊复合涂层具有良好的超疏水疏油性能，对水的接触角为157.5度，对二碘甲烷的接触角为133.67度。以酸、碱及多种有机溶剂浸渍处理该复合涂层，发现该涂层对有机溶剂表现出良好的耐侵蚀能力，而酸、碱处理会使其疏水性有所下降；但室温12h、或60度6h、或短时日照处理均可使其超疏水性能恢复至未受损水平，而且可以实现多次循环修复。采用双面胶带黏附法、砂纸打磨法以及落沙实验对复合涂层进行刮蹭磨损破坏，发现双面胶带黏附对涂层性能无影响。复合涂层可经受100g砝码1000目砂纸近2000个磨损循环而无损于其超疏表面性能，其可修复次数取决于涂层厚度。落沙实验也证实，该复合涂层在表面破坏、超疏性能丧失后，室温放置2天可自发恢复其超疏性能。该可修复型超疏涂层的构筑方法简单，原料选择多样，适用基材范围广泛，具有较强的应用前景。