Abstract: A series of styrene-sodium methacrylate copolymer dispersants were prepared, and the effects of molar ratio on the yield and adsorption on imidacloprid particle surface were investigated. The dispersant was the best when molar ratio of two monomers was 0.8. The adsorption kinetics, isotherm and thermodynamics of the best dispersant on imidacloprid particle surfaces were studied. Adsorption layer thicknesses of dispersant at different temperature were determined by XPS. The adsorption process followed the pseudo-second-order kinetic model with a good correlation coefficient. The adsorption process was fitted with the Langmuir isotherm equation better. Thermodynamic parameters indicated that the adsorption was a spontaneous exothermic process, and higher temperature was not beneficial to the adsorption process. DH_ad < 40 kJ·mol^-1 indicated that the adsorption process was physical adsorption. The adsorption layer thickness decreased with temperature increase. By comparison with the adsorption characteristics of other commercial dispersants, styrene-sodium methacrylate copolymer was eligible for the dispersant on water-based formulations of imidacloprid.

Key words: imidacloprid, surfactant, adsorption, kinetics, thermodynamics

摘要： 通过溶液聚合合成一系列苯乙烯-甲基丙烯酸钠共聚物分散剂.研究了不同单体摩尔比对其产率和在吡虫啉颗粒表面吸附性能的影响,结果表明当两种单体摩尔比为0.8时分散剂的产率和吸附性能相对最优.通过振荡吸附实验研究了最优分散剂在吡虫啉颗粒表面的吸附动力学、等温线和热力学,由XPS近似计算不同温度下分散剂的吸附层厚度.结果表明:吸附动力学符合伪二级动力学方程;吸附等温线符合Langmuir模型;吸附热力学表明该吸附为自发、放热、熵增过程,高温不利于吸附进行;DH_ad < 40 kJ·mol^-1表明该吸附过程为物理吸附;吸附层厚度随温度升高而降低.通过与其他商品化分散剂对比可知该共聚物适合作为分散剂用于吡虫啉的水基化剂型.

关键词: 吡虫啉, 表面活性剂, 吸附, 动力学, 热力学