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采用正硅酸四乙酯为前驱体,氨水为催化剂,在溶胶过程中添加聚乙二醇(PEG),调控溶胶结构,获得具有不同性能的多孔SiO_2凝胶薄膜。研究了PEG添加量和平均分子量对溶胶黏度、镀膜时溶胶的结构以及薄膜的表面形貌和光学性能的影响。结果表明:PEG的引入能够快速增大溶胶的黏度,促进溶胶中粒子的生长,提高颗粒之间的交联度并诱导粒子呈现出均匀的环状结构。随着PEG添加量的增加,薄膜表面的疏松程度先增加后逐渐变为致密结构,薄膜折射率在1.10~1.47之间可调,而镀膜玻璃的透过率先缓慢增加到99.32%,然后迅速降低。随着PEG平均分子量的增加,薄膜表面的大孔先逐渐增多然后变为致密结构;镀膜玻璃的透过率降低,最高为99.73%;薄膜折射率在1.14~1.38之间可调。
Tetraethyl orthosilicate was used as precursor and ammonia as catalyst. Polyethylene glycol (PEG) was added into the sol to control the structure of the sol. The porous SiO 2 gel film with different properties was obtained. The effects of PEG addition amount and average molecular weight on the viscosity of sol, the structure of sol during coating and the surface morphology and optical properties of the films were investigated. The results showed that the introduction of PEG can rapidly increase the viscosity of sol, promote the growth of sol particles, increase the degree of crosslinking between particles and induce the particles to have a uniform ring structure. With the increase of PEG content, the looseness of the film surface first increases and then becomes a dense structure. The refractive index of the film is adjustable between 1.10 and 1.47, while the transmittance of the coated glass slowly increases to 99.32% and then decreases rapidly . With the increase of the average molecular weight of PEG, the macropores on the surface of the film gradually increase and then become denser. The transmittance of the coated glass decreases to a maximum of 99.73%. The refractive index of the film can be adjusted between 1.14 and 1.38.