塑料微球表面制备聚乙烯醇涂层研究进展

在聚苯乙烯（PS）-聚乙烯醇（PVA）-碳氢聚合物（CH）三层球的设计中制备PVA涂层的方法主要包括乳液微封装法、炉内成球涂层法、浸(旋)涂法、界面缩聚法及喷涂法等，前三种方法目前最为常用。总结了前三种制备PVA涂层方法的优缺点及目前的研究和制备现状。乳液微封装法适合于500 m以下小尺寸双层球的制备，具有微球成活率高、产品质量较好等优点，但制备过程受人为因素影响较大，且不易制备大直径双层球。炉内成球涂层法也适用于小尺寸双层球的制备，其制备周期短，但液滴发生器的设计苛刻，PVA层的均匀性差，且不易制得较大尺寸的双层球。浸（旋）涂法可制备1000 m以上的大直径双层球，但该方法中影响PVA涂层铺展的因素较多，得到的PVA涂层均匀性较差，且涂层很薄。

Research progress of fabricating polyvinyl alcohol coating on plastic microsphere

In the procedures of designing polystyrene-polyvinyl alcohol-CH (carbon and hydrogen elements) (PS-PVA-CH) triple-layer microspheres, there are many methods such as drop-tower technique, emulsion micro-encapsulation, dip (spin) coating, interfacial polycondensation, and spraying technique to prepare the PVA coating. Drop-tower technique, emulsion micro-encapsulation and dip (spin) coating are most-commonly used. The advantages, disadvantages and the research progress of the three methods are summarized in this paper. Emulsion micro-encapsulation is suitable for preparing double-layer microspheres of sizes smaller then 500 μm, with high survival ratio and good quality. However, the preparation process is easily influenced by artificial factors. Small-sized double-layer microspheres can also be prepared by the drop-tower technique, and the preparation period is short. But there are still some problems such as the difficulty in designing the droplet generator, uneven PVA coating and the difficulty in preparing large-sized microspheres. Dip (spin) coating technique can be used to prepare PS-PVA microspheres with sizes larger than 1000 μm, but the spread of PVA coating is affected by many factors in this method, and the prepared PVA coating is too thin and not uniform.