含氟丙烯酸酯聚合物接枝纳米二氧化硅粒子自分层法构筑超疏水涂层

Superhydrophobic coating shows extensive use prospects in the fields of surface self-cleaning, anti-ice and flow drag reduction. The composite coatings containing inorganic nano particles and low-surface-energy polymer are widely applied, but nano particles fill the whole range of coatings, leading to low stability and durability for the coating because of fragility and loss in adhesion although the coating can provide superhydrophobic performance..In this application, we designed a asymmetrical superhydrophobic coating, of which inorganic nano silica particles are distributed in the surface layer, showing superhydrophobic behavior, and one polar polymer occupies the range inside the coating showing well adhesion with the substrate. This structure is formed by self-stratifying of grafted particles /polar polymer system driving by lower total interface energy. Thus, the grafting particles could bring the perfect combination of surface roughness and low surface energy. We will realize the grafting process via reversible addition-fragmentation chain transfer polymerization (RAFT). Furthermore, the aggregation structure of grafting chains can be adjusted by controlling grafting density, structural unites and degree of polymerization, for optimizing the self-stratifying and obtaining high-performance superhydrophobic coatings. This work will provide a new research strategy for fabricating superhydrophobic coating, and our preparation will be suitable for broad use because of mild and simple routes.

超疏水涂层在表面自清洁、防覆冰和流体减阻领域展示了广阔的应用前景。无机纳米粒子/低表面能聚合物复合超疏水涂层应用较广，但无机纳米粒子充斥涂层空间，引发涂层脆性且损害附着力，难以稳定、持久地保持超疏水性。.本申请针对上述问题，设计了一种非对称结构的超疏水涂层，其表层分布着低表面能聚合物接枝的无机纳米粒子，显示超疏水性；而涂层内部则为一种极性聚合物，与基体牢固结合。该结构是在更低的总界面能驱使下，接枝粒子在极性聚合物中的分散体系发生自分层行为的产物。于是分布在涂层表面的接枝粒子实现了表面粗糙度与低表面能的完美结合。项目将采用可逆‒加成‒断裂链转移聚合法(RAFT)实施无机粒子的接枝，严格控制接枝链密度、聚合度、结晶性等因素，进而控制接枝链聚集态特征，使自分层行为得到优化，最终获得非对称超疏水涂层。本项目为超疏水涂层的制备提供了一种新的策略，所提出的制备方法温和简捷，适宜大规模应用。

本项目旨在通过纳米粒子表面引发的可逆加成—断裂—链转移(RAFT)接枝聚合技术，得到核-壳形态的接枝粒子，使其具有纳米粒子的形貌和功能化的表面。项目的主要技术路线为：①在纳米二氧化硅上进行RAFT试剂的表面锚固；②通过锚固的RAFT试剂发生表面接枝聚合；③对表面接枝层形貌进行研究与调控。项目实施期间先后进行了自由基引发剂锚固纳米二氧化硅引发的表面接枝聚合(接枝粒子宏观显示150°以上的接触角)，硅烷功能化RAFT试剂直接锚固纳米二氧化硅引发的表面接枝聚合以及通过分步改性—锚固RAFT试剂于球形二氧化硅粒子表面引发的接枝聚合，其中最后一种研究策略导致最有效的表面接枝效果。该工艺所得产物中，聚合物能够完全占据接枝粒子表面，且粒子尚可体现其原本的形貌。本项目最初的设计意图是设计低表面能的核-壳粒子，利用表面能梯度使聚合物涂层中的粒子迁移到涂层表面，从而满足超疏水材料的两个条件—低表面能和高表面粗糙度。目前本项目已经实施了聚合物接枝二氧化硅粒子RAFT接枝聚合的工艺探索，并通过对接枝粒子化学组成、表面形貌的性能表征证实了聚合物接枝层的存在。本项目其他的目标仍未实现。本项目期望在达成既定目标后，将该技术用于自清洁、耐玷污涂料中，减少涂层的维护成本，延长涂层使用寿命。