SiO_2气凝胶纳米多孔结构的自组装过程模拟

Self-assembly Simulation of Nano-porous Structure of Silica Aerogel

基于分子动力学理论,模拟并计算了纳米多孔SiO_2气凝胶的原子尺度模型和力学性能。SiO_2气凝胶网络结构的自组装形成过程表明,当密度为0.078 g/cm3时,形成的结构以纳米团簇为主,难以形成连通的骨架结构;当密度为0.172 g/cm3及以上时,硅氧元素分布已扩展形成了连通的无定形骨架结构。通过对不同密度体系模型单轴施加应变并计算相应的应力值,得到应力-应变关系曲线,并依据弹性范围求得弹性模量。模拟结果表明,弹性模量与密度成一次线性关系,当气凝胶密度在0.078~0.443 g/cm3时,弹性模量为0.1265~0.7889 MPa。

The atomic scale model and mechanical properties of SiO2 aerogels was simulated and calculated based on the principle of molecular dynamics. The results indicates that the structure is mainly nano-clusters and connected skeleton structure is difficult to form when the density is 0. 078 g/cm^3. The distribution of silica oxygen elements has been extended to a connected amorphous skeleton structure when the density is 0. 172 g/cm^3 and above. The stress-strain relationships curve were figured out by applying strains on the different density cell, and the elastic modulus was obtained in different elastic range. The simulation results shows that the elastic modulus is linear with the density. The elastic modulus changes from 0. 1265 MPa to 0. 7889 MPa when density ranges from O. 078 g/cm3 to 0. 443 g/ 3 cm .