In this article, pure epoxy resin and silica–epoxy nanocomposite models were established to investigate the effects of hyperbranched polyester on microstructure and thermomechanical properties of epoxy resin through molecular dynamics simulation. Results revealed that the composite of silica can improve the thermomechanical properties of nanocomposites, including the glass transition temperature, thermal conductivity, and elastic modulus. Moreover, the thermomechanical properties were further enhanced through chemical modification on the silica surface, where the effectiveness was the best through grafting hyperbranched polyester on the silica surface. Compared with pure epoxy resin, the glass transition temperature of silica–epoxy composite modified by silica grafted with hyperbranched polyester increased by 38 K. The thermal conductivity increased with the increase of temperature and thermal conductivity at room temperature increased to 0.4171 W/(m·K)⁻¹ with an increase ratio of 94.3%. Young’s modulus, volume modulus, and shear modulus all fluctuated as temperature rise with a down overall trend. They increased by 44.68%, 29.52%, and 36.65%, respectively, when compared with pure epoxy resin. At the same time, the thermomechanical properties were closely related to the microstructure such as fractional free volume (FFV), mean square displacement (MSD), and binding energy. Silica surface modification by grafting hyperbranched polyester reduced the FFV value and MSD value most and strengthened the combination of silica and epoxy resin matrix the best, resulting in the best thermomechanical properties.

在本文中，建立纯环氧树脂和二氧化硅-环氧纳米复合材料模型，通过分子动力学模拟研究超支化聚酯对环氧树脂微观结构和热机械性能的影响。结果表明，二氧化硅复合材料可以提高纳米复合材料的热机械性能，包括玻璃化转变温度、导热系数和弹性模量。此外，通过在二氧化硅表面进行化学改性，进一步增强了热机械性能，其中通过在二氧化硅表面接枝超支化聚酯效果最佳。与纯环氧树脂相比，由二氧化硅接枝超支化聚酯改性的二氧化硅-环氧复合材料的玻璃化转变温度提高了 38 K。^-1，增加率为94.3%。杨氏模量、体积模量和剪切模量均随温度升高而波动，总体呈下降趋势。与纯环氧树脂相比，它们分别增加了44.68%、29.52%和36.65%。同时，热机械性能与微观结构密切相关，如分数自由体积 (FFV)、均方位移 (MSD) 和结合能。接枝超支化聚酯的二氧化硅表面改性使FFV值和MSD值降低最多，并最好地加强了二氧化硅与环氧树脂基体的结合，从而获得了最佳的热机械性能。