National Institute of Materials Physics, R-077125 Magurele, Romania.
Spectrochim Acta A Mol Biomol Spectrosc. 2010 Apr;75(4):1228-35. doi: 10.1016/j.saa.2009.12.029. Epub 2009 Dec 16.
Composites prepared from aerosil A380 and liquid crystals (LCs) of 4-n-alkyl-4'-cyanophenyl benzoate type, with four to six carbon atoms in the alkyl chain were investigated by infrared spectroscopy. Their high silica content (of 2-7 g aerosil/1 g of LC) was given by thermogravimetric investigations and allows the observation of a rather thin LC layer on the silica particles. Several surface species onto the external surface of the grains were demonstrated. Arguments are given that monomer and dimer species are present in the bulk cyanophenyl benzoate materials while bulk-like species along with hydrogen-bonded ones coexist in the so-called surface layer of the composites. The main interaction of LC molecules with the aerosil surface is by hydrogen bonding taking place with the involvement of the cyan group. There is a contribution of ester carbonyl group to these surface interactions but this cannot be well quantified.
采用红外光谱法研究了由气相法二氧化硅 A380 和烷基链中含有 4 至 6 个碳原子的 4-正-烷基-4'-氰基苯基苯甲酸酯型液晶（LC）制备的复合材料。通过热重分析可知其二氧化硅含量较高（每克 LC 有 2-7 克气相法二氧化硅），这允许在二氧化硅颗粒上观察到相当薄的 LC 层。在外表面的颗粒上证明了几种表面物质的存在。有证据表明，单体和二聚体物质存在于块状氰基苯甲酸酯材料中，而类似块状的物质与氢键共存于复合材料的所谓表面层中。LC 分子与气相法二氧化硅表面的主要相互作用是通过涉及氰基的氢键发生的。酯羰基基团对这些表面相互作用有一定的贡献，但无法很好地定量。
