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分别以3-(甲基丙烯酰氧)丙基三甲氧基硅烷(MPS)和辛基三甲氧基硅烷(OTMS)为活性和惰性硅烷的代表,对SiO2进行不同锚固密度的表面修饰,并以改性SiO2的甲基丙烯酸甲酯(MMA)单体分散液为原料,通过原位本体聚合制得一系列SiO2含量不同的高分散性SiO2/PMMA复合材料.考察SiO2表面基团活性程度和SiO2含量对聚合反应动力学、基体聚合物分子量以及复合材料硬度的影响,探究修饰状态不同SiO2在本体自由基聚合中的作用机制.发现SiO2表面硅羟基及其锚固MPS的活性双键会对聚合反应起阻缓聚作用,进而会显著降低基体聚合物的分子量及复合材料的硬度.而惰性硅烷OTMS对SiO2表面的锚固则会消耗SiO2表面硅羟基、并屏蔽其影响,因而随着OTMS锚固密度的提高,基体分子量和复合材料硬度均会随之提高,特别是当表面修饰达到饱和状态时,SiO2的阻缓聚作用已可忽略.
The surface modification of SiO2 with different anchoring densities was carried out by using 3- (methacryloyloxy) propyltrimethoxysilane (MPS) and octyltrimethoxysilane (OTMS) as active and inert silanes respectively. A series of highly dispersed SiO2 / PMMA composites with different SiO2 contents were prepared by in-situ bulk polymerization using a modified methyl methacrylate (MMA) monomer dispersion as starting material. The effects of SiO2 surface group activity and SiO2 Content on the polymerization kinetics, the molecular weight of the matrix polymer and the hardness of the composite material to explore the role of different modified state of SiO2 in the bulk free radical polymerization mechanism.It was found that the SiO2 surface of the hydroxyl and anchor MPS active double bond polymerization reaction Which can reduce the molecular weight of the matrix polymer and the hardness of the composites significantly.The anchoring of the inert silane OTMS on the SiO2 surface will consume the silanol groups on the SiO2 surface and shield the influence of the silanol groups, Increase, the matrix molecular weight and the hardness of the composite material will be increased, especially when the surface modification to saturation, SiO2 retarding retarding effect has been neglected.