Preparation of Inorganic/Organic Composite by Sol-Gel Process in the Presence of Polymer-Grafted Ultrafine Inorganic Particles and Its Solvent-Sensing Properties

我们研究了一种新型的无机/有机复合材料的制备通过溶胶-凝胶过程中存在的聚合物接枝的无机超细粒子和在各种溶剂中的复合材料的溶剂传感性能。在聚N-乙烯基-2-吡咯烷酮接枝炭黑和聚2-甲基-2-恶唑啉接枝炭黑的存在下，进行正硅酸乙酯的溶胶-凝胶反应，得到炭黑颗粒均匀掺入的深黑色硅胶/炭黑复合材料。利用自由基引发剂，在复合材料表面进行了乙烯基单体的自由基接枝聚合反应。在聚合过程中，部分乙烯基聚合物通过复合材料中炭黑粒子的自由基清除反应接枝到复合材料表面，接枝率为3- 8%。硅胶/炭黑复合材料的溶剂吸附性能随炭黑表面接枝聚合物链和复合材料表面对浸渍溶剂的溶解度而变化。在炭黑表面和复合材料表面的接枝聚合物链都是良溶剂的情况下，硅胶/炭黑复合材料选择性地吸附溶剂。聚合物接枝硅胶/炭黑复合材料的电阻对接枝聚合物链的良溶剂也非常敏感：在炭黑表面和复合材料表面的接枝聚合物链的良溶剂中电阻急剧下降，但在两个表面的接枝聚合物链的不良溶剂中电阻变化不大。

We examined the preparation of a novel inorganic/organic composite by sol-gel process in the presence of polymer-grafted inorganic ultrafine particles and the solvent-sensing properties of the composite in the various solvents. When sol-gel reaction of tetraethoxysilane was carried out in the presence of poly (N-vinyl-2-pyrrolidone)-grafted, and poly (2-methyl-2-oxazoline)-grafted carbon black, a deep black silica gel/carbon black composite in which carbon black particles were uniformly incorporated was obtained. The radical graft polymerizations of vinyl monomers onto the prepared composite surface was tried by use of radical initiators in the presence of the composite. During the polymerizations, part of the resultant vinyl polymers grafted onto the composite surface by the radical scavenging reaction of carbon black particles in the composite: the percentage of grafting was in the range of 3-8%. The solvent adsorption properties of the silica gel/carbon black composite varied with the solubility of grafted polymer chains on the carbon black surface and the composite surface toward the immersion solvent. In the case of the good solvent for both the grafted polymer chains of the carbon black surface and the composite surface, the silica gel/carbon black composite selectively adsorbed the solvent. Electric resistance of the polymer-grafted silica gel/carbon black composite was also very sensitive to the good solvent of the grafted polymer chains: the electric resistance drastically decreased in good solvent of both the grafted polymer chains of the carbon black surface and the composite surface, but it sparingly changed in poor solvent of the grafted polymer chains on both surfaces.