Silicone, also known as polysiloxane, is a typical semi-inorganic polymer material with repeated (-Si-O-Si-) bonds as the main chain and organic groups directly connected to silicon atoms. According to the required properties, the silicone polymer materials with different molecular structures can be prepared by changing the molecular structure of silicon, changing the organic groups bound to silicon atoms, and choosing different curing methods. Different modification methods, fillers, and processes are used to prepare organosilicon polymer materials with different molecular structures. It is customary to call silane monomer and polysiloxane as silicone compounds, polysiloxane liquid as silicone oil, and polysiloxane rubber as silicone rubber and polysiloxane resin as silicone resin.
In the power supply industry, silicone materials can be used in bonding and fixing adhesive for power supply components, power filling and sealing adhesive for modules, thermal conductive silicone grease and thermal conductive mud, etc. Medical silicone rubber can be widely used in medical devices, life sciences, drugs and other fields. With the development of technology, polysiloxane rubber and silicone oil will also be widely used in daily sealing, electronics, medical and health and other fields of the national economy, and people's life, and play an important role in the high-tech industry.
According to the side group on the silicone rubber main chain, silicone rubber can be divided into hydrosiloxane, epoxy terminated polysiloxane, epoxy terminated polysiloxane, hydroxyl polysiloxane, trifluoropropyl polysiloxane, and so on. According to the different side groups and compound formulations, silicone rubber with different uses can be obtained.
- Hydrogen-containing siloxane: Hydrogen-containing siloxane can be used to prepare side-chain liquid crystal ionomers with siloxane as the main chain. When liquid crystal ionomers are used in polymer blends, the interfacial properties of components can be effectively improved. Ionomers improve the compatibility of components by increasing the interaction between components. In the electronic industry, polysiloxane side-chain liquid crystals are expected to be used as electrical components, structural materials, electronic materials, and other devices because of their special optical properties, electromagnetism, and good mechanical properties. In addition, the biggest advantage of methyl hydrogen-containing silicone oil is its cross-linking film-forming property. Under the catalysis of metal salts, it can be cross-linked at a lower temperature, and a stable waterproof film is formed on the surface of many materials. It can be used as a waterproofing agent for glass, ceramics, fabrics, paper, and other materials.
- Epoxy-terminated polysiloxane: Hyperbranched amino modified polysiloxane is prepared by using diethylenetriamine and epoxy-terminated polysiloxane as raw materials through the nucleophilic ring-opening reaction between the epoxy group and amino group, which improve the softness and hydrophilicity of the finished fabric. The silicone resin modified by the epoxy group at both ends of the molecule has excellent adhesion, high mechanical strength after curing, good chemical stability, low coefficient of thermal expansion, and good heat resistance. It is widely used as the binder, electrical insulation material, foam, and so on.
- Vinyl-terminated polysiloxane: Some researchers have prepared electronic potting adhesives using vinyl-terminated liquid silicone oil as the matrix and oligosiloxane containing silicon-hydrogen bonds as the vulcanization crosslinking agent. Compared with pure silicone rubber, its thermal conductivity, tensile strength, and breaking strength have all been improved to varying degrees. The raw material of the electronic potting compound itself has electrical insulation performance, breathability performance, non-toxicity, heat resistance performance, and chemical stability performance, and is the first choice material for the potting of electronic and electrical assembly parts. Electronic potting adhesive products prepared with polysiloxane as a matrix are also environmentally friendly materials.
Figure 1. Vinyl-terminated dimethyl polysiloxane.
- Li Hongjing, Liu Weiqu, Wei Zhenjie.(2010) “Epoxy-terminated silicone oil modified epoxy resin performance study”. China Plastics. 24 (7):51-54.
- Liu Yanjie, Wu Minghua, Hou Yanmin.(2014) “Synthesis and application of hyperbranched amino-modified polysiloxane”. Journal of Textiles.35(12):73-80.