阳离子型聚氨酯-脲-胺在二氧化硅水溶胶听吸咐行为

研究了水溶性阳离子聚氨酯-脲-胺乙酸盐在球形、单分散的纳米二氧化硅水分 散注保的吸附行为。PUUA分子链在烯溶液中呈较舒展的构象，分子尺寸小于纳米氧 化硅的粒径。PUUA通过van der Waals作用力和氢键吸附在氧化硅表面。在稳喧吸 附后，等温吸附线呈线性上升，且没有极限值。吸附量随纳米氧化硅粒径的增大、 胶粒表面电荷的减少和电解质乙酸钢加入量的变化均以相同的斜率线性下降。 PUUA分子量增加，吸附量增加，且分子量大的PUUA优先吸附于氧化硅胶粒表面，静 电吸引是PUUA吸附至氧化硅溶胶粒表面的主要作用力。PUUA在氧化硅胶粒上的吸咐 使体系表现粘度下降，敏化作用使体系呈假塑性，而保护作用使体系呈胀流型。

Adsorption of Poly(urethane-urea-amine) Acetate on Colloidal Silica

The adsorption of water-soluble cationic poly(urethane-urea-amine) acet ate (PUUA) on colloidal silica as aqueous dispersion was studied. The results i ndicated that the conformation of the PUUA chains was in stretched conformation in dilute solution, and the average molecular size was smaller than the diamete r of silica particles. The adsorption of PUUA onto the colloidal silica was attr ibuted to van der Waals' and hydrogen bonding forces. The adsorption isotherms r evealed that, after stable adsorption on the surface of silica particle, the ads orption amount of PUUA linearly increased, moreover, there was not an ultimate s aturated adsorption. The apparent adsorption was linearly, by the same slope, de creased with increase of the colloidal silica size, falling of the surface charg es of silica, and increase of the amount of sodium acetate added. Furthermore, the adsorption was ascended with increasing molecular weight of PUUA, and the a dsorption of the large molecules was prior to the small molecules of PUUA. The e lectrostatic attraction was the predominant effect on the adsorption of the PUU A from water onto the colloidal silica. The apparent viscosity of the dispersion was decreased by the adsorption of the PUUA-E onto the colloidal silica. The s ensitivity of the dispersions showed pseudoplastic flow, while the protection of the dispersions displayed dilatancy.