论文部分内容阅读
以苯乙烯、甲基丙烯酸甲酯为主单体 ,丙烯酸为功能单体合成了三元无皂乳液共聚胶粒。用TEM观测了胶粒形态、大小及其分布 ;以电导滴定法测定了胶粒表面 -COOH的密度。考察了不同的聚合阶段加入不同量的丙烯酸对所得胶粒形态、大小及其表面 -COOH的密度的影响。结果表明 :在聚合前加入丙烯酸 ,随着丙烯酸浓度的增大 ,胶粒粒径减小、分散系数增大 ;在成核后期滴加丙烯酸 ,胶粒粒径较大且随丙烯酸浓度增大粒径变化不大而分散系数迅速增大 ;在聚合完成期滴加丙烯酸 ,胶粒粒径最大且在一定范围内随着丙烯酸浓度的增大 ,粒径和分散系数增大。不论丙烯酸以哪种方式加入 ,随着丙烯酸浓度的增大胶粒表面 -COOH密度增大 ;在相同丙烯酸浓度下 ,聚合完成期滴加丙烯酸所得胶粒表面 -COOH密度最大 ,聚合前加入丙烯酸所得胶粒表面 -COOH密度最小。
With styrene, methyl methacrylate as the main monomer, acrylic acid as a functional monomer synthesis ternary soap-free emulsion copolymer particles. The morphology, size and distribution of colloidal particles were observed by TEM. The density of -COOH on colloidal particles was measured by conductivity titration. The effects of adding different amounts of acrylic acid on the morphology, size and surface-COOH density of the obtained micelles were investigated at different polymerization stages. The results showed that acrylic acid was added before polymerization, with the increase of acrylic acid concentration, the particle size decreased and the dispersion coefficient increased. At the later stage of nucleation, acrylic acid was added dropwise. The particle size of colloidal particles increased with the increase of acrylic acid concentration Diameter changes rapidly and the dispersion coefficient increases rapidly. When acrylic acid is added dropwise during the completion of polymerization, the particle size of colloidal particles is the largest and within a certain range, the particle size and dispersion coefficient increase with the increase of acrylic acid concentration. Regardless of which way acrylic acid was added, the density of -COOH on the surface of the colloidal particles increased as the acrylic acid concentration increased. At the same acrylic acid concentration, the -COOH density on the surface of the colloidal particles obtained by the dropwise addition of acrylic acid during the polymerization was the largest. Particle surface -COOH density minimum.