Microsponge Molecular Reserviors and Their Use in the Heterogenization of Homogeneous Catalysts

多孔聚合物颗粒在色谱、离子交换、反应性聚合物基质和药物控释等应用中很有用。这些大网状颗粒的合成，一般是基于由单体、交联剂、引发剂和适当的惰性液体组成的分散相的悬浮聚合，这种惰性液体不聚合，并起成孔剂的作用。所获得的颗粒的大小取决于悬浮介质及其所含的分散剂。通过改变孔隙剂的体积分数和调节交联剂的浓度来控制颗粒的孔隙度。本项目有两个目标：(1)开发制备多孔微米级颗粒的新方法，并学会控制其内表面积和孔径分布；(2)在均相催化剂的异质化领域提出一些应用。提出了一种基于浓乳液聚合法制备多孔聚合物颗粒的新方法。通过机械搅拌将疏水（亲水）液体分散到含有表面活性剂的亲水（疏水）液体中，得到浓缩乳液。分散相的体积分数应大于0.74，代表最致密的等半径球体排列的体积分数，最大可达0.99。浓缩乳液具有凝胶的外观和行为，因此易于处理。通过表面活性剂在分散液滴表面的吸附，使浓缩乳状液稳定。该浓缩乳液法采用小体积分数的连续相，从而采用少量疏水相制备亲水性颗粒。将制备三种多孔颗粒：(1)多孔交联疏水颗粒；(2)由交联聚苯乙烯多孔坚果壳包裹的稀疏聚氯乙烯（乙烯基苄基）基质；(3)聚丙烯酰胺或其他亲水聚合物的多孔交联亲水性颗粒。将研究的一些应用包括使用第二类合成的材料来捕获钴羰基阴离子，以及使用第三类合成的材料来固定与亲水性孔相容的酶。＊＊＊

9301711 Ruckenstein Porous polymer particles are useful in applications such as chromatography, ion exchange, reactive polymer matrixes, and for controlled release of drugs. The synthesis of these macroreticular particles is, in general, based on the suspension polymerization of a dispersed phase that consists of monomer, crosslinking agent, initiator, and a suitable inert liquid which does not polymerize and that functions as a porogen. The size of the particles obtained depends upon the suspending medium as well as the dispersant it contains. The porosity of the particles is controlled by varying the volume fraction of the porogen and adjusting the concentration of the crosslinking agent. This project has two goals: (1) to develop new methods for the preparation of porous micron-size particles and to learn to control their internal surface area and their pore size distribution, and (2) to suggest some applications in the area of the heterogenization of homogeneous catalysts. The development of a new method for the preparation of porous polymer particles based on the concentrated emulsion polymerization method is planned. The concentrated emulsion is obtained by dispersing a hydrophobic (hydrophilic) liquid into a surfactant-containing hydrophilic (hydrophobic) liquid with mechanical stirring. The volume fraction of the dispersed phase should be larger than 0.74, which represents the volume fraction of the most compact arrangement of spheres of equal radii, and can be as large as 0.99. The concentrated emulsions have the appearance and behavior of gels and therefore can be handled easily. The concentrated emulsion is stabilized by the adsorption of the surfactant on the surface of dispersed droplets. This concentrated emulsion method employs a small volume fraction of continuous phase thus a small amount of the hydrophobic phase is employed to prepare hydrophilic particles. Three kinds of porous particles will be prepared: (1) porous crosslinke d hydrophobic particles, (2) sparse poly(vinylbenzylchloride) matrices encapsulated by porous nutshells of crosslinked polystyrene, and (3) porous crosslinked hydrophilic particles of polyacrylamide or other hydrophilic polymers. Some applications that will be studied include using the second category of materials synthesized to entrap cobalt carbonyl anions and materials synthesized under the third category to immobilize enzymes that are compatible with the hydrophilic pores. ***