The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler network of silica. Nevertheless, the filler network structure and corresponding reinforcement mechanism are still under debate and need to be further probed with the aid of applicative advanced analysis techniques. Herein, small-angle neutron scattering (SANS) and synchrotron radiation X-ray nano-computed tomography (Nano-CT) techniques are employed to explore the evolution of filler networks of fumed, precipitated and sol-gel silica, respectively. Our studying results reveal the formation of filler network constructed by the interconnecting of branched silica aggregates. And the silica with highly associated structure, pertaining to amorphous morphology, small size, and large surface area, presents short distance and effective molecular chain bridge between aggregates, thus forming strong and steady filler networks. This work would provide deep-seated revisiting of filler networks and corresponding reinforcement mechanism and offer guidance for optimizing the mechanical properties of silicone rubber.

硅橡胶复合材料由于具有由基质的分子网络和二氧化硅的填料网络构成的双网络结构，因此具有出色的机械性能。然而，填料网络的结构和相应的增强机制仍在争论中，需要借助先进的分析技术进一步探讨。在本文中，小角度中子散射（SANS）和同步辐射X射线纳米计算机断层扫描（Nano-CT）技术分别用于探索气相法，沉淀法和溶胶-凝胶法二氧化硅填料网络的演变。我们的研究结果揭示了由支链二氧化硅聚集体相互连接构成的填料网络的形成。而具有高度缔合结构的二氧化硅，属于无定形形态，小尺寸，且表面积大，聚集体之间存在短距离且有效的分子链桥，从而形成坚固而稳定的填料网络。这项工作将为填料网络和相应的增强机理提供深入的探讨，并为优化硅橡胶的机械性能提供指导。