常温常压下有机-无机杂化对SiO2光学薄膜微观结构的调控机理

The regulation mechanism of organic-inorganic on the microstructure of silica optical thin films at ambient temperature and pressure was investigated. This provides theoretical basis for preparation of silica thin films with controlled and ultra-low refractive indices. The organic-inorganic hybrid methods include the co-condensation of TEOS with organically modified monomer, surface hydrophobic modification of silica particles and the combination of them. After systematically characterization of the properties of silica sols and thin films, the relationship between the microstructures and properties of silica sols and thin films was investigated, and the regulation mechanism of organic-inorganic on the microstructure of silica thin films was explained. Finally, silica thin films with controlled refractive indices between 1.0 and 1.20 were prepared after optimization of organically modified monomer and process condition. The investigation of this project fills the void of preparation of silica thin film with refractive indices between 1.0 and 1.20 by normal sol-gel process. In addition, it also provides useful reference for preparation of thin films, sheet and bulky materials with ultra-low refractive index or ultra-high porosity.

本项目研究常温常压条件下有机-无机杂化对SiO2光学薄膜微观结构的调控机理，为实现SiO2光学薄膜折射率的连续可控和超低折射率化提供理论依据。有机-无机杂化的途径为有机改性单体与正硅酸乙酯共聚、SiO2粒子表面强疏水修饰以及两者相结合。系统研究有机-无机杂化对SiO2溶胶和薄膜性质的影响，建立溶胶和薄膜的微观结构与宏观性能之间的关系，阐明有机-无机杂化对SiO2光学薄膜微观结构的调控机理。在此基础上，筛选有机改性单体和优化工艺条件，制备折射率在1.0-1.20之间连续可控的超低折射率SiO2薄膜。本项目的研究弥补了常规溶胶-凝胶法无法实现折射率在1.0-1.20之间连续可控的SiO2薄膜的缺憾，同时也为简单条件下制备具有超低折射率（或超高孔隙率）的薄膜、片材和块材（如气凝胶）等提供实验借鉴。

光学薄膜是光学元件不可或缺的一部分。折射率是光学薄膜最重要的物理量，决定其光学性能。在惯性约束核聚变（ICF）等光学系统中，高性能的反射膜和增透膜能够显著提高光的利用效率。超低折射率和折射率连续可变的薄膜是制备高性能反射膜和增透膜等光学薄膜的关键。本项目研究常温常压下有机-无机杂化对SiO2光学薄膜微观结构的调控机理。通过系统而深入的研究，探索有机-无机杂化调节溶胶粒子和薄膜微观结构的机理，建立溶胶和薄膜的微观结构与宏观性能之间的关系。通过对有机-无机杂化调节溶胶和薄膜微观结构机理的建立，为制备折射率在1.0-1.20之间的超低折射率薄膜提供理论依据。研究结果表明，将(EtO)3SiCH3、(EtO)3SiC3H7、(EtO)3SiC6H13、(EtO)3SiVi等有机单体与TEOS共聚时，能够使光学薄膜的折射率在1.0-1.20之间连续调控；而将(EtO)3SiC8H17、(EtO)3SiC12H25和(EtO)3SiPh与TEOS共聚时，能够使光学薄膜的折射率在1.20-1.40之间连续调控。筛选有机改性单体为(EtO)3SiVi，仅通过简单地改变(EtO)3SiVi与TEOS的摩尔比，实现薄膜折射率在1.12-1.21之间连续可调；筛选有机改性单体为(EtO)3SiPh，仅通过简单地改变(EtO)3SiPh与TEOS的摩尔比，实现薄膜折射率在1.21-1.27之间连续可变；制备的宽频增透膜在500-1100之间的平均透过率高达98.5%。本项目建立了溶胶和薄膜的微观结构与宏观性能之间的关系，阐明了常温常压条件下有机-无机杂化对薄膜微观结构调控的机理，为简单条件下制备折射率可控的超低折射率薄膜乃至其它结构可控多孔材料（如片材、板材和块材等）提供理论依据和实验借鉴。同时，本项目制备的具有超低折射率的薄膜是激光系统光学元件表面宽频增透膜的关键材料。