Study for Understanding and Formulation of the Kinetics and Mechanisms of Radical Polymerizations Taking Place inside Dispersed Nano-Size Monomer Droplets

在分散的纳米尺寸单体液滴内部发生的自由基聚合中，聚合速率众所周知受到自由基进入这些液滴和自由基从这些液滴解吸的影响已经认识到，不存在可以解释在这些纳米颗粒内部发生的自由基聚合的动力学和机制的通用理论。为了阐明液滴尺寸对聚合速率的影响，我们通过使用微流化器和水不溶性单体改变单体液滴的尺寸来进行自由基聚合，其中通过奥斯特瓦尔德熟化的颗粒生长是可忽略的。然而，作为具有分散的纳米尺寸单体液滴的替代体系，我们使用具有纳米尺寸单体溶胀的聚合物颗粒的聚合体系，这是准备 ...更多信息 为了在单体溶胀的粒子中产生自由基，采用典型的油溶性引发剂2，2 '-偶氮二从所获得的结果表明，（1）在颗粒内部产生的大多数成对自由基瞬间双分子终止，自由基脱附速率与自由基终止速率之比取决于粒子的大小.这些实验结果表明，定量测定发生在非离子型聚合物内部的自由基脱附速率和自由基终止速率是可行的。液滴尺寸是使分散纳米级单体液滴自由基聚合理论具有普适性的关键因素。此外，我们进行了自由基聚合，在更细的纳米尺寸的单体液滴（微乳液液滴），通过添加大量的乳化剂制备，并可以预测所得到的聚合物颗粒的尺寸分布的机理模型考虑到上述知识。少

In radical polymerizations taking place inside dispersed nano-size monomer droplets, the rate of polymerization is well known to be affected by both radical entry into and radical desorption from these droplets irrespective of the site of radical generation (continuous or droplets phases).It was recognized that there is no universal theory that can explain the kinetics and mechanisms of radical polymerization taking place inside these nano-size monomer droplets.In order to clarify the effect of droplet-size on the rate of polymerization, we carried out radical polymerizations with changing the size of monomer droplets by using Microfluidizer and water-insoluble monomers, where the particle growth via Ostwald ripening was negligible.However, it was found that the change in droplet-size via coagulation was inevitable.As an alternative system having dispersed nano-size monomer droplets, we employed a polymerization system having nano-size monomer-swollen polymer particles, which were prep … More ared via onventional emulsion polymerization.This is the so-called "seeded polymerization".In order to generate radicals in the monomer-swollen particles, a representative oil-soluble initiator, 2, 2'-azobis(isobutyronitrile) was used.From the results obtained, it was indicated that(1)most of pair radicals generated inside the particles instantaneously terminated bimolecularly, and hardly contribute to polymerization1 and(2)the ratio of the rate of adical desorption to the rate of radical termination depends on the size of the particles.These experimental results suggest us that quantification of the rates of radical desorption and radical termination taking place inside the nono-size droplets is a key factor to have a universal theory for adical polymerization consisting of dispersed nano-size monomer droplet. Furthermore, we carried out, radical polymerization in much finer nano-size monomer droplets(microemulsion droplets)prepared by adding a larger amount of emulsifier, and could predict the size distribution of resultant polymeric particles by the mechanistic model taking the above-mentioned knowledge into consideration. Less