以聚合物为壳材包覆芯材形成的聚合物微胶囊，尺寸小，比表面积大，壳材稳定，壳材对内部物质具有很好的保护和缓释作用，在工业、生物、医药、储能等领域受到广泛关注。聚合物微胶囊的制备方法有很多种，包括界面聚合法、原位聚合法、相分离法、喷雾干燥法，以及多种针对特殊性能和应用的新方法等。近年来，关于微胶囊的研究主要集中在制备和应用领域，对微胶囊形成过程和形成机理的研究报道相对较少，揭示微胶囊的形成过程和形成机理对于微胶囊的可控制备以及拓展微胶囊的应用领域是非常重要的。本研究主要采用界面聚合法和原位聚合法制备了聚合物微胶囊，选择合适的制备条件，得到了形貌规整、性能优良的微胶囊。对微胶囊形成过程中的形貌变化进行观察，推测其形成机理。 采用界面聚合法，以十六烷为芯材，脂肪族异氰酸酯（异佛尔酮二异氰酸酯）与四乙烯五胺反应，制备了以聚脲作为壳材的微胶囊。当选择聚乙烯醇作乳化剂时，得到的微胶囊形貌规整、壳层致密，粒径分布较窄，热分析显示芯材含量可以达到60%。 采用界面聚合法，异佛尔酮二异氰酸酯直接和水反应，不需要加入胺即得到了形貌良好、粒径分布窄的聚脲微胶囊，与异氰酸酯和胺反应结果相比，微胶囊表面更加光滑，芯材含量更高（可达70%以上），且具有更好的热稳定性。通过改变油溶性单体异佛尔酮二异氰酸酯的加入量，控制反应的进行程度，观察了不同阶段微胶囊的形貌变化，并借此推测界面聚合中聚脲微胶囊的形成过程。 采用原位聚合法，以尿素和甲醛为反应单体，不经过预聚反应，通过一步法制备了脲醛树脂作壳材的微胶囊。研究了不同反应条件（pH值、壳材用量、交联剂等）对微胶囊形貌和性能的影响。反应过程中取出不同时间的产物进行形貌观察及分析，得出了一步法制备过程中，以脲醛树脂为壳材的微胶囊形成过程：首先形成脲醛纳米颗粒，纳米颗粒在油/水界面处沉积并进一步交联固化，经过不断的沉积和交联，最终生成无孔致密的脲醛树脂球壳。
Microcapsules consist of internal core materials and external shell materials which are mainly polymers. Microcapsules have plenty of advantages, including small size, high capacity, large specific surface area and stable shells. The major function of microcapsules is to protect internal materials from outer environment and to release materials into the external environment in a controlled manner. Recently, microcapsules have attracted lots of attention and have been widely used in industry, biology, medicine, energy storage and other fields. There are a variety of methods that microcapsules could be prepared, such as interfacial polymerization, in situ polymerization, phase separation, spray drying and various new methods aiming at special performance and applications. In the past few decades, studies of microcapsules mainly focused on the preparation and application, few focused on the formation process and formation mechanism of microcapsules. However, understanding the formation process and mechanism of microcapsules is quite important for preparing satisfactory microcapsules and enlarging their applications. In our study, microcapsules with uniform morphology and excellent properties were prepared via interfacial polymerization and in situ polymerization. The morphology changes of microcapsules in the forming process were observed, and the forming mechanism of microcapsules was tried to deduce. The microcapsules with polyurea shell and hexadecane core were prepared by interfacial polymerization method. Isophorone diisocyanate(IPDI) and Tetraethylenepentamine were used as monomers in the system. Microcapsules with uniform morphologies, compact shells and narrow size distribution were obtained when using PVA (PVA 1788) as emulsifier. Thermoanalysis indicated that the content of core material could reach to 60%. Adopting interfacial polymerizayion, polyurea microcapsules were obtained via the reaction of Isophorone diisocyanate and water without amine. Comparing with the polyurea microcapsules made via the reaction of isocyanate and amine, the polyurea microcapsules obtained via the reaction of IPDI and water had more smooth surface, higher content of core material (reaching to 70%) and better thermal stabilities. By means of changing the content of IPDI and controlling the reaction process, the morphology changes of the microcapsules in different stages were observed and the formation process of polyurea microcapsules prepared by interfacial polymerizatyion was deduced. Urea-formaldehyde resin microcapsules were prepared by the in situ polymerization of urea and formaldehyde without prepolymerization, which was named after the one-step reaction. The effect of different reaction conditions on the morphologies and properties of the microcapsules were investigated, including pH, the content of shell materials and the cross-linking agent. During the reaction, the morphologies of the products in different time were observed, and the one step preparation of urea-formaldehyde resin microcapsules were analyzed. The results show that UF nano particles were first formed and deposited in the oil-water interface. Then the nano particles got cross-linked and solidified. After continuous deposition and cross linking, compact and imperforate urea-formaldehyde resin shell was finally formed.
