Abstract Silica/polydimethylsiloxane nanocomposites (denoted as SiO2/PDMS) prepared by physical mixing exhibit poor processing flexibility and strength associated with the high viscosity effect and low addition amount of silica during the fabrication of room-temperature vulcanized PDMS elastomer. Thus a facile and scalable one-step “inhibition-grafting” method was established to graft polydimethylsiloxane (PDMS) onto the surface of DNS-2 (a kind of dispersible nano-silica with network structure) to yield nano-SiO2/PDMS high-performance nanocomposites. Their microstructure and chemical structure were characterized by TEM, GPC, FTIR and TGA. The viscosity and rheological properties were evaluated, and their mechanical properties of the as-prepared nano-SiO2/PDMS elastomers were measured as well. Findings indicate that PDMS chains are grafted on the silica surface via covalent bonding and the chains either grafted on the silica or in free state interpenetrated silica network thereby forming a kind of interpenetrating network. This kind of interpenetrating network and short PDMS chains can provide more crosslinking sites, leading to low viscosity and high mechanical properties of SiO2/PDMS composites. Besides, the nano-SiO2/PDMS elastomers containing over 16 phr (phr: parts of silica per hundred parts of PDMS by weight) of nano-silica exhibit shear thinning behavior, which corresponds to the transformation from Newtonian fluids to non-Newtonian fluids associated with the formation of whole interpenetrating network between nano-silica and PDMS chains. In summary, the nano-SiO2/PDMS elastomers exhibit a low viscosity and good mechanical properties, which is favorable for promoting their applications in the industry of high performance silicone materials.

中文翻译：

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纳米二氧化硅填料对“抑制-接枝”法制备的聚二甲基硅氧烷基纳米复合材料微观结构和力学性能的影响

摘要 通过物理混合制备的二氧化硅/聚二甲基硅氧烷纳米复合材料（表示为 SiO2/PDMS）表现出较差的加工灵活性和强度，这与制备室温硫化 PDMS 弹性体过程中的高粘度效应和低二氧化硅添加量有关。因此，建立了一种简便且可扩展的一步“抑制-接枝”方法，将聚二甲基硅氧烷（PDMS）接枝到 DNS-2（一种具有网络结构的可分散纳米二氧化硅）表面，得到纳米 SiO2/PDMS 高性能纳米复合材料。通过TEM、GPC、FTIR和TGA对其微观结构和化学结构进行了表征。评估了粘度和流变性能，并测量了所制备的纳米 SiO2/PDMS 弹性体的机械性能。研究结果表明，PDMS 链通过共价键接枝在二氧化硅表面，这些链要么接枝在二氧化硅上，要么以游离态互穿二氧化硅网络，从而形成一种互穿网络。这种互穿网络和较短的 PDMS 链可以提供更多的交联位点，从而使 SiO2/PDMS 复合材料具有低粘度和高机械性能。此外，含有超过 16 phr（phr：按重量计每 100 份 PDMS 的二氧化硅份数）纳米二氧化硅的纳米 SiO2/PDMS 弹性体表现出剪切稀化行为，这对应于从牛顿流体到非牛顿流体的转变。随着纳米二氧化硅和PDMS链之间形成完整的互穿网络。总之，