红外宽频吸收硅基复合气凝胶的制备及表征

以正硅酸乙酯为硅源，采用酸碱两步催化法经过溶胶-凝胶和冷冻干燥制备出SiO2气凝胶基材，并在凝胶老化过程中添加三乙胺盐酸盐得到兼具中远红外吸收特性的硅基复合气凝胶。利用X射线衍射、扫描电子显微镜、氮吸附-脱附和傅里叶红外吸收光谱对气凝胶的结构和性能进行了表征。结果表明:胺盐在硅气凝胶网络结构中穿插结晶；基材的比表面积、最大孔容和平均孔径分别为524.5 m2/g、1.2 cm3/g和9.2 nm，复合材料的比表面积、最大孔容和平均孔径分别为37.93~138.7 m2/g、0.08~0.28 cm3/g和7.1~8.8 nm；基材和复合气凝胶的表观密度分别为0.25 g/cm3和0.35~0.51 g/cm3；复合气凝胶在中远红外窗口具有宽频吸收的特性，且三乙胺盐酸盐含量的增加，中红外相对吸收强度成比例增强。

Preparation and characterization of silica composite aerogels with broadband IR absorption

The silicon aerogel substrate was prepared by a two-step base/acid catalyzed sol-gel process using tetraethoxysilane(TEOS) as silicon source and by freeze drying. By adding different content of triethylamine hydrochloride(TEAHCl) to the substrate during the aging process, composite aerogels with broadband absorption in mid-and far-infrared windows was prepared. The structure and property of composity aerogels were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), N2 physisorption at 77 K and Fourier-transform infrared spectroscopy(FT-IR). Results show that the triethylamine hydrochloride is crystallized adhering to the whole three-dimensional network of silicon aerogel. The silicon aerogel substrate has the specific surface area about 524.5 m2/g, total pore volume about 1.2 cm3/g and average pore diameter about 9.2 nm. The composite aerogels have the specific surface area about 37.93-138.7 m2/g, total pore volume about 0.08-0.28 cm3/g and average pore diameter about 7.1-8.8 nm. The apparent density of silicon aerogel substrate and composite aerogels are 0.25 g/cm3 and 0.35-0.51 g/cm3 respectively. The composite aerogels have the characteristic of broadband absorption in mid-and far-infrared windows. The relative absorption intensity in mid-infrared window increased in proportion with the increase of TEAHCl.