基于Pickering乳液聚合法制备新型水性PUA基纳米复合皮革涂饰材料的成膜机理与性能调控

近年，Pickering(皮克林)乳液聚合法以其在制备新材料和处理因表面活性剂大量使用带来的生态环境问题等方面的独特优势而备受关注。二维纳米片晶laponite独特的结构和性质使其在稳定乳液聚合体系方面十分具有优势。本项目针对制革工业发展对高物性水性聚氨酯(PU)皮革涂饰材料的清洁化合成之急需，以laponite为稳定剂，选择丙烯酸酯类(PA)单体稀释的PU预聚液为分散相，构建皮克林乳液聚合体系，制备PUA纳米复合皮革涂饰材料。既避免传统PU乳液聚合中乳化剂造成的性能缺陷和溶剂污染，又充分结合PU和PA各自性能优势及纳米粒子的增强增韧作用。深入研究过程条件对体系分子结构的影响及粒子在界面上的吸附；阐明以乳液稳定剂这种新方式引入纳米粒子对聚合物乳液成膜过程、结构和性能的影响规律；揭示成膜机理，建立制备条件-结构-性能的关联性，为皮克林乳液聚合法制备高性能皮革涂饰材料及产业化应用积累基础数据。

Recently, Pickering emulsion polymerization has received considerable attention due to its unique advantages in the designing of novel materials and solving the environmental problems caused by the large amounts of traditional surface active agents. Laponite is a kind of synthetic trioctahedric hectorite clay with two-dimensional nanosize and can be dispersed as individual disk-shaped colloids in water, which make it as ideal and promising particle to stabilize Pickering emulsion polymerization. For current leather industry, there is an urgent need to develop environment-friendly polymerization process for waterborne polyurethane (WPU) coating material to meet the increasing requirement of clean production. In this project, we propose to design and synthesize a novel polyurethane-acrylate/laponite (PU-PA/laponite) nanocomposite by the Pickering emulsion polymerization process. First, the Pickering emulsion containing acrylate monomers and PU pre-polymer terminated with carbon-carbon double bonds as oil phase is stabilized by lamellar-structured laponite nanoparticle. Then the free radical polymerization reaction inside the emulsion droplets is initiated between PU pre-polymer and acrylate monomers to synthesize the PU-PA/laponite nanocomposites coating material. This approach can avoid the drawbacks of traditional emulsifier and the pollution of organic solvent. Besides, the laponite nanoparticles absorb onto the polymer latex particles during the emulsion polymerization process, therefore the PU can also be reinforced by laponite and acrylate. We will systematically study the keys factors in polymerization reaction process and their effect on the emulsion stability, the molecular structure of PU-PA/laponite and the adsorption behavior and distribution of laponite on the oil-water interface and polymer latex particles surface. Moreover, the effect of laponite used as stabilizer on the film-forming process, micro-structure, performance of PU-PA/laponite coating and the practical applications of the finished crust leather will be evaluated. The mechanism of film-forming of the novel polymer emulsions obtained by Pickering emulsion polymerization, as well as the relationship between the microstructure and performance of the coating materials will be revealed. The goal of this project is to provide a promising strategy for the solvent-free preparation of leather coatings material with excellent properties, and accumulate basic valuable data for the study and application of Pickering emulsion polymerization in the construction of novel polymer emulsions and related functional materials.