Daniels MW, Francis LF
Center for Interfacial Engineering, University of Minnesota, Minneapolis, Minnesota, 55455
J Colloid Interface Sci. 1998 Sep 1;205(1):191-200. doi: 10.1006/jcis.1998.5671.
The adsorption of 3-glycidoxypropyltrimethoxysilane (GPS) onto silica colloids (20 nm diameter) suspended in an isopropanol/water solution was studied and related to the microstructure and properties of coatings prepared from the suspensions. 29Si NMR results indicate an adsorption limit of approximately 2.2 GPS monomer or repeat units per nm2 of silica surface after 24 h in suspension. For coatings dried at 100 degreesC, FTIR data show that surface silanols are further consumed as GPS is added beyond the adsorption limit in the suspension. The increased adsorption after drying may be related to enhanced reaction at the higher temperature and to drying-induced deposition onto the surfaces. Coating microstructures consist of randomly packed silica colloids with varying amounts of siloxane polymer filling the pores, depending on the amount of silane added. The critical cracking thickness of the coatings increased dramatically when the amount of silane added was sufficient to fill the porespace. Abrasion resistance of the coatings improved gradually with GPS content, but deteriorated when the GPS content was far in excess of that needed to fill the pores. Hardness measured by nanoindentation showed a similar trend as abrasion resistance. Copyright 1998 Academic Press.
研究了3-缩水甘油氧基丙基三甲氧基硅烷（GPS）在悬浮于异丙醇/水溶液中的二氧化硅胶体（直径20 nm）上的吸附情况，并将其与由该悬浮液制备的涂层的微观结构和性能相关联。29Si NMR结果表明，在悬浮24小时后，二氧化硅表面每平方纳米约有2.2个GPS单体或重复单元的吸附极限。对于在100℃下干燥的涂层，FTIR数据显示，当悬浮液中的GPS添加量超过吸附极限时，表面硅醇会进一步消耗。干燥后吸附量增加可能与较高温度下反应增强以及干燥诱导的表面沉积有关。涂层微观结构由随机堆积的二氧化硅胶体组成，根据硅烷添加量的不同，孔隙中填充有不同量的硅氧烷聚合物。当硅烷添加量足以填充孔隙空间时，涂层的临界开裂厚度显著增加。涂层的耐磨性随GPS含量逐渐提高，但当GPS含量远远超过填充孔隙所需量时，耐磨性会下降。通过纳米压痕测量的硬度显示出与耐磨性相似的趋势。版权所有1998年学术出版社。
