Properties of poly(N-isopropylacrylamide)-grafted colloidal silica
Properties of poly(N-isopropylacrylamide)-grafted colloidal silica
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DOI：
10.1006/jcis.2000.6871
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发表时间：
2000-07-15
影响因子：
9.9
通讯作者：
Hrymak, AN
中科院分区：
文献类型：
--
作者：
Liu, J;Pelton, R;Hrymak, AN
采用自由基聚合法合成了N-异丙基丙烯酰胺-甲基丙烯酸3-三甲氧基硅丙酯共聚物，并将其接枝到球形硅胶表面。平均每条链具有1个甲硅烷基的共聚物在60 ℃下缩合在分散于THF中的二氧化硅上。所得颗粒在室温下的氯化钙临界凝结浓度为500 mM I，表明具有强大的胶体稳定性。相比之下，将悬浮液加热至50 ℃使临界凝聚浓度降低了三个数量级以上，得到0.1 mM的值。因此，PNIPAM壳诱导二氧化硅分散体中的温度敏感的胶体稳定性。涂覆的二氧化硅颗粒也是表面活性的。然而，在25 ° C下50 mJ/m（2）的表面张力比PNIPAM溶液的相应值高15%。(C)北京大学出版社.
Poly(N-isopropylacrylamide-co-3-trimethoxysilylpropyl methacrylate) was prepared by radical polymerization and was grafted onto the surface of spherical colloidal silica. The copolymer, which had on average 1 silyl group per chain, condensed on the silica dispersed in THF at 60 degrees C. The resulting particles had a critical coagulation concentration of calcium chloride of 500 mM I at room temperature, indicating robust colloidal stability. By contrast, heating the suspension to 50 degrees C lowered the critical coagulation concentration by more than three orders of magnitude, giving a value of 0.1 mM. Thus, the PNIPAM shell induced temperature-sensitive colloidal stability in the silica dispersion. The coated silica particles were also surface active. However, the surface tension of 50 mJ/m(2) at 25 degrees C is 15% higher than the corresponding value for PNIPAM solutions. (C) 2000 Academic Press.