论文部分内容阅读
在不添加任何乳化剂的条件下,将甲基丙烯酸(MAA)和苯乙烯(St)单体进行无皂乳液聚合,制备纳米聚合物微球。由于采用的搅拌速率较低,单体相和水相呈现层状分布,聚合反应速率由单体扩散速率控制。跟传统的动力学控制乳液聚合法相比,扩散控制所得产物粒径较小,最小可达35nm,且乳液稳定性较好。采用傅里叶变换红外光谱仪(FTIR)、动态激光光散射(DLS)、核磁(1 HNMR)、扫描电镜(SEM)对其进行表征。并研究了反应温度、引发剂用量、单体摩尔配比对乳液稳定性和微球粒径的影响,发现反应温度在80℃,引发剂的占单体质量百分数为25%,单体摩尔配比1:2.5的时候乳液稳定,微球最小粒径35nm,57.7%的粒子小于100nm。
Nano-polymer microspheres were prepared by Soap-free emulsion polymerization of methacrylic acid (MAA) and styrene (St) without adding any emulsifier. Due to the lower agitation rate used, the monomer and water phases appear to be layered and the rate of polymerization is controlled by the monomer diffusion rate. Compared with the traditional kinetic controlled emulsion polymerization, the particle size of the product obtained by diffusion control is smaller, the minimum is 35nm, and the emulsion stability is better. The structures were characterized by Fourier transform infrared spectroscopy (FTIR), dynamic laser light scattering (DLS), nuclear magnetic resonance (1HNMR) and scanning electron microscopy (SEM). The effects of reaction temperature, initiator dosage and molar ratio of monomers on the stability of the emulsion and the particle size of the microspheres were investigated. It was found that the reaction temperature is 80 ℃, the monomer percentage of the initiator is 25% The emulsion was stable at a ratio of 1: 2.5. The microspheres had a minimum particle size of 35 nm and 57.7% of the particles were less than 100 nm.