目的:水性涂料作为有机溶剂型体系的可持续替代品正在迅速发展。通常将无机胶体添加到水性聚合物分散体中以增强水性涂料的性能。然而,这些双峰分散体具有许多可导致不稳定的胶体和不期望的相分离的界面。单个胶体之间的共价键,在聚合物-无机核-电晕上胶体组件上,可以减少或抑制涂层干燥过程中的不稳定性和相分离,提高其机械和光学性能。
方法:使用具有核心-电晕草莓构型的水性聚合物-二氧化硅suproolloids来精确控制涂层内的二氧化硅纳米颗粒分布。对聚合物和二氧化硅颗粒之间的相互作用进行微调,以获得共价结合或物理吸附的suproolloid。通过在室温下干燥半胶体分散体制备涂层,它们的形态和力学性能相互联系。
结果:共价结合的suproolloids提供了具有均匀3D渗滤二氧化硅纳米网络的透明涂层。仅具有物理吸附作用的suporloids,导致在界面处具有分层二氧化硅层的涂层。排列良好的二氧化硅纳米网大大提高了涂层的储能模量和耐水性。这些suprolloidal分散体为制备具有增强的机械性能和其他功能的水性涂料提供了新的范例,像结构颜色。
OBJECTIVE: Water-borne coatings are rapidly expanding as sustainable alternatives to organic solvent-borne systems. Inorganic colloids are often added to aqueous polymer
dispersions to enhance the performance of water-borne coatings. However, these bimodal
dispersions have many interfaces which can result in unstable colloids and undesirable phase separation. The covalent bonding between individual colloids, on a polymer-inorganic core-corona supracolloidal assembly, could reduce or suppress instability and phase separation during drying of coatings, advancing its mechanical and optical properties.
METHODS: Aqueous polymer-silica supracolloids with a core-corona strawberry configuration were used to precisely control the silica nanoparticles distribution within the coating. The interaction between polymer and silica particles was fine-tuned to obtain covalently bound or physically adsorbed supracolloids. Coatings were prepared by drying the supracolloidal
dispersions at room temperature, and their morphology and mechanical properties were interconnected.
RESULTS: Covalently bound supracolloids provided transparent coatings with a homogeneous 3D percolating silica nanonetwork. Supracolloids having physical adsorption only, resulted in coatings with a stratified silica layer at interfaces. The well-arranged silica nanonetworks strongly improve the storage moduli and water resistance of the coatings. These supracolloidal
dispersions offer a new paradigm for preparing water-borne coatings with enhanced mechanical properties and other functionalities, like structural color.