Kinetic Factors in Miniemulsion Polymerization

乳液聚合在工业上用于生产聚合物乳胶，用于涂料、粘合剂、粘合剂、油漆和泡沫等应用。在此过程中，聚合物颗粒在稳定乳化剂的存在下产生，单体从大液滴（直径大于约10微米）扩散到直径约0.1至0.4微米的生长颗粒。乳液聚合的另一种选择是微乳液聚合，其中单体相首先通过使用混合乳化剂系统以直径约为0.05至0.4微米的小而稳定的液滴的形式分散到水相中。这些微型乳液是通过在通常的乳液聚合配方中加入助表面活性剂（例如十六烷或十六醇）形成的，通常含有十二烷基硫酸钠作为表面活性剂。引发聚合随后在单体液滴中发生，产物聚合物颗粒与初始单体液滴大小大致相同。为了对微乳液聚合的机理有更基本的了解，pi计划：1。确定颗粒/水界面和单体/聚合物颗粒的组成对自由基进入和离开液滴/颗粒的速率的影响。2. 测试现有的方法，以确定对这种非均相聚合机理有直接影响的进入和退出速率系数。3. 确定液滴/液滴、颗粒/液滴和颗粒/颗粒不稳定性的相对重要性及其对微乳液聚合的影响。4. 通过模拟微乳液聚合动力学，考察宽度对颗粒/液滴尺寸分布的影响，从而接近对实际体系的更真实的描述。

Emulsion polymerization is used in industry for the production of polymer latexes for applications such as coatings, binders, adhesives, paints and foams. In this process, polymer particles are created in the presence of stabilizing emulsifiers with diffusion of monomer from large droplets (greater than approximately 10 microns in diameter) to the growing particles which are approximately 0.1 to 0.4 microns in diameter. An alternative to emulsion polymerization is miniemulsion polymerization in which the monomer phase is first dispersed into the aqueous phase in the form of small and stable droplets in the size range of approximately 0.05 to 0.4 microns in diameter through the use of a mixed emulsifier system. These miniemulsions are formed by the addition of a co-surfactant (for example hexadecane or cetyl alcohol) to the usual emulsion polymerization recipe, typically containing sodium dodecyl sulfate as surfactant. Initiation an polymerization then take place in the monomer droplets and the product polymer particles are approximately the same size as the initial monomer droplets. To gain a more fundamental understanding of the mechanisms involved in miniemulsion polymerizations, the PIs plan to: 1. Determine the effect of the composition of the particle/water interface and the monomer/polymer particle on the entry and exit rates of free radicals to and from the droplets/particles. 2. Test the existing methodologies for the determination of the entry and exit rate coefficients which have a direct bearing on the mechanisms of this heterogeneous polymerization. 3. Determine the relative importance of droplet/droplet, particle/droplet, and particle/particle instabilities and their influence on miniemulsion polymerization. 4. Examine the effect of the breadth in the particle/droplet size distributions through simulations of the miniemulsion polymerization kinetics, hereby approaching a more realistic description of an actual system.