Yoshinaga K, Shimada J, Nishida H, Komatsu M
Department of Applied Chemistry, Kyushu Institute of Technology, Sensui 1-1, Tobata, Kitakyushu, 804-0015, Japan
J Colloid Interface Sci. 1999 Jun 15;214(2):180-188. doi: 10.1006/jcis.1999.6182.
Effects of surface-grafted polymer on the dispersibility of polymer-silica composite particles in ethyl acetate-methanol cosolvent were investigated. The composite particles were prepared by a two-step modification of monodisperse colloidal silica (120 nm in diameter). Modifications were carried out by first reacting the surface silanol of the colloidal silica with maleic anhydride-styrene copolymer silane coupling agent to prevent aggregation and then grafting, in acetone or tetrahydrofuran, amino group-terminated poly(methyl acrylate), poly(methyl methacrylate), or polystyrene to the maleic anhydride moiety on the surface. For poly(methyl acrylate) and poly(methyl methacrylate) graftings, composite particles with long polymer chains aggregated in methanol-rich cosolvent due to insoluble secondary polymer chain interaction among the particles. Particles with a small amount of relatively low-molecular-weight secondary polymer were dispersible in the methanol content range from 0 to 90 vol%. Polystyrene-modified particles never aggregated, even in 90 vol% methanol solution. An ESR study of the suspension in ethyl acetate-hexane cosolvent suggested that the dispersibility of these composite particles in ethyl acetate-rich solution is attributable to steric repulsion between solvated and expanded secondary polymer chains among the particles. The dispersibility of the composite particles in methanol-rich solution was controlled by a delicate balance between the electrostatic repulsion and the interparticle attraction due to the desolvated and insoluble polymer chain interaction among the particles. Copyright 1999 Academic Press.
研究了表面接枝聚合物对聚合物 - 二氧化硅复合颗粒在乙酸乙酯 - 甲醇混合溶剂中分散性的影响。复合颗粒通过对单分散胶体二氧化硅（直径120nm）进行两步改性制备。改性首先通过使胶体二氧化硅的表面硅醇与马来酸酐 - 苯乙烯共聚物硅烷偶联剂反应以防止聚集，然后在丙酮或四氢呋喃中将氨基封端的聚丙烯酸甲酯、聚甲基丙烯酸甲酯或聚苯乙烯接枝到表面的马来酸酐部分上。对于聚丙烯酸甲酯和聚甲基丙烯酸甲酯接枝，由于颗粒间不溶性二级聚合物链相互作用，具有长聚合物链的复合颗粒在富含甲醇的混合溶剂中聚集。具有少量相对低分子量二级聚合物的颗粒在甲醇含量为0至90体积％的范围内是可分散的。聚苯乙烯改性的颗粒即使在90体积％的甲醇溶液中也不会聚集。对乙酸乙酯 - 己烷混合溶剂中的悬浮液进行的ESR研究表明，这些复合颗粒在富含乙酸乙酯的溶液中的分散性归因于颗粒间溶剂化和膨胀的二级聚合物链之间的空间排斥。复合颗粒在富含甲醇的溶液中的分散性由颗粒间脱溶剂化和不溶性聚合物链相互作用引起的静电排斥和颗粒间吸引力之间的微妙平衡控制。版权所有1999年学术出版社。
