关于超疏水涂层的制备有许多研究, 其中硅衍生物涂层是一个重点, 然而硅衍生物形成机理的研究还鲜有报道。 以硅酸钠和乙烯基三乙氧基硅烷（VTES）作为硅衍生物的反应物, 利用近红外光谱（near infrared, NIR）和二维相关分析(2D-correlation analysis, 2DCorr)方法探讨硅衍生物的反应机理。 首先, 采用德国Bruker公司的MPA型傅里叶近红外光谱仪采集样品的光谱信息, 分析了17 Wt%硅酸钠、 97 Wt% VTES以及两者1:5摩尔比混合体系的分子结构变化特征, 结果发现: 混合体系在5 176~4 250 cm-1范围内出现了Si—O—H和Si—O—Si基团的吸收峰, 说明溶液中两者混合后发生了水解缩合反应; 并发现10 262 cm-1处的游离羟基减少并向低频方向偏移, 8 905 cm-1处以氢键缔合的羟基增加; 含氢键的醇从7 203 cm-1偏移到6 846 cm-1。 将硅酸钠和VTES按照7种不同摩尔比混合并搅拌成溶胶凝胶状, 采集这些样品的光谱信息, 并且对吸收峰进行归属, 结果发现: 随着VTES的比例增加, 游离羟基以及含氢键的醇减少, 结合羟基增加, 含硅基团也在增加。 最后, 对不同摩尔比的混合体系的光谱数据进行基线校正, 运用软件Matlab 6.5计算基于摩尔比例扰动的二维相关光谱, 提高近红外光谱的分辨率和分析不同官能团之间的变化顺序。 结果发现: 10 262 cm-1处吸收峰的变化先于8 905 cm-1处吸收峰的变化, 7 026（6 846） cm-1处吸收峰的变化晚于5 859 cm-1处吸收峰的变化, 5 264（5 176） cm-1处吸收峰的变化晚于4 397 cm-1处吸收峰的变化, 4 667 cm-1处吸收峰的变化晚于4 397 cm-1处吸收峰的变化。 不同波数的吸收峰变化顺序对应其归属的官能团的变化顺序, 进而揭示了近红外光谱中基团变化的原因。 硅酸钠和VTES两种溶液混合后形成的溶胶凝胶是具有三维网状结构的硅-聚合物, 这种聚合物具有疏水性质能被广泛应用。 研究结果将有利于更深刻地理解硅酸钠和VTES混合体系水解缩合反应过程以及分子结构变化, 为其进一步的研究和使用提供参考。

There are many studies on the preparation of superhydrophobic coatings, among which silicon derivative coating is a key point. However, there are a few reports on the formation mechanism of silicon derivatives.In this paper, sodium silicate and ethylene triethoxysilane (VTES) were used as reactants of silicon derivatives. The reaction mechanism of silicon derivatives was studied by near infrared spectroscopy (NIR) and two dimensional correlation analysis (2DCorr). Firstly, the spectral information of samples was collected by MPA Fourier near infrared spectrometer of Bruker Company,Germany. The molecular structure changes of 17 Wt% sodium silicate, 97 Wt% VTES and their blend of 1∶5 molar ratio were analyzed. The results showed that the absorption peaks of Si—O—H and Si—O—Si groups appeared in the range of 5 176~4 250 cm-1 in sodium silicate/VTES blend, which indicated that the hydrolysis and condensation reaction took place after the solutions were mixed. In addition, the free hydroxyl groups at 10 262 cm-1 decreased and shifted to low frequency, and hydroxyl groups associated with hydrogen bond increased at 8 905 cm-1. Secondly, sodium silicate and VTES were mixed and stirred into sol-gel shape according to seven different molar ratios. The spectral information of the samples was also collected by near infrared spectrometer, and the absorption peaks of the related groups in sodium silicate/VTES blend were assigned.The results showed that with the increase of VTES ratio, the number of free hydroxyl groups and alcohols containing hydrogen bond decreased, while the number of combined hydroxyl groups and silicon groups increased. Finally, the spectral data of sodium silicate/VTES blend with different molar ratios were corrected by baseline correction,and the two-dimensional correlation spectra based on molar proportion disturbance were calculated by using the software Matlab 6.5. So, the resolution of the near infrared spectrum was improved and the change sequence among different functional groups was analyzed. The results showed that the change of absorption peak at 10 262 cm-1 was prior than that at 8 905 cm-1, the change of absorption peak at 7 026(6 846) cm-1 was later than that at 5 859 cm-1, the change of absorption peak at 5 264(5 176) cm-1 was later than that at 4 397 cm-1, and the change of absorption peak at 4 667 cm-1 was later than that at 4 397 cm-1. The variation order of absorption peak at different wavenumber corresponded to the variation order of functional group assigned to them, which further revealed the reason for the change of functional groups in near infrared spectra. The sol-gel formed by blending two solutions of sodium silicate and VTES is a silicon-polymer with three-dimensional network structure. The polymer has hydrophobic properties and can be widely used. The results will be helpful to understand the hydrolysis and condensation reaction process and molecular structure changes of sodium silicate /VTES blend, and provide reference for further research and application.