As a polymer material, silicone resin is widely used because of its excellent heat resistance, cold resistance, radiation resistance, water repellency, stain resistance, chemical corrosion resistance and other special properties. However, pure silicone resin has disadvantages such as long curing time, low coating adhesion at high temperature, and low mechanical strength, which limit its application. Since the molecular structure of the silicone resin still retains active groups such as hydroxyl groups, it provides more possibilities for the modification of the silicone resin. As the main film-forming substance of silicone resin coatings, silicone resin has received extensive attention in its modification. This paper mainly reviews the research progress of modified silicone resins in the fields of high temperature resistant coatings, wear resistant coatings and antifouling coatings.

1. High temperature resistant coating
The difference from organic polymers is that the bond energy of Si-O bonds in silicone resins is higher than that of C-C bonds in ordinary organic polymers, and silicon atoms and oxygen atoms form d-pπ bonds, so silicone resins have a very high bond energy. good thermal stability.

1.1 Epoxy resin modified silicone resin
Epoxy modified silicone resin is a graft condensation reaction between epoxy group and hydroxyl group of epoxy resin and polysiloxane active group, so the modified epoxy/silicone coating has good stability and compatibility. There are advantages of epoxy resin and silicone resin.
For epoxy-modified silicone resins, Zhenning Sun et al. prepared epoxy-modified silicone polymers and applied the modified resins to anti-splash coatings for engine blades.
Through Fourier transform infrared spectroscopy (FTIR) analysis, the hydroxyl groups in the silicone resin successfully reacted with epoxy groups, indicating that the epoxy resin is chemically modified to the silicone resin.
Thermogravimetric analysis (TG) showed that with the increase of hydroxysilicone oil content in the system, the thermal stability of the modified polymer was better, and it could be better applied to the blade anti-splash coating.

1.2 Inorganic filler modified silicone resin
When the branch chain of silicone resin contains phenyl group, its content can affect the heat resistance of the coating, because the electron-rich cloud in the phenyl group can interact with the pigment, filler and substrate to enhance the adhesion of the coating.
Therefore, the use of inorganic fillers to fill and modify the silicone resin film-forming material can give the coating better performance.
Ding Chao et al. used silicone resin as film-forming resin and added temperature-resistant fillers such as aluminum-silver paste and mica powder to develop a single-component high-temperature anti-corrosion coating that can be used for a long time at 500 °C.
The flaky structure of mica powder itself is beneficial to improve the temperature resistance of the coating. The experiment shows that the dosage of aluminum-silver paste in the formula should be controlled at 10%~15%, and the dosage of mica powder should be controlled at 12%~15%. The silicone high temperature resistant coating with this content ratio can show excellent thermal stability. sex.

1.3 POSS (polyhedral oligomeric silsesquioxane) modified silicone resin
The addition of nano-SiO2, carbon nanotubes, clay and other nanoparticles can improve the thermal and mechanical properties of polymers.
However, it is difficult to achieve nanodispersion by mechanical blending due to the agglomeration of nanoparticles.
While POSS is a unique organic/inorganic nanomaterial, the non-reactive group can improve the compatibility with silicone resin, and the reactive group can realize chemical bonding with silicone resin, which can well solve this problem. question.
Liu Y R et al. successfully synthesized methyl silicone resin/POSS composites with higher decomposition temperature by mixing functionalized trisiloxybutyl POSS with hydroxylated methyl silicone resin.
Yang Z synthesized a series of silicone resins containing silicon benzene units into the POSS framework, which improved the thermal stability of the silicone resins.
Yao X et al. synthesized 3 kinds of polyhedral oligomeric silsesquioxane, which significantly improved the thermal stability by adding POSS to the silicone resin, and obtained the thermal stability of aminopropyl POSS modified silicone resin The most significant increase is the conclusion that the decomposition temperature is nearly 45°C higher than that of pure silicone resin.

In addition, Yao X et al. also studied the thermal decomposition mechanism of silicone resins with different POSSs. Chemical simulations showed that hydrogen bonds were formed between POSS and silicone resins, which greatly improved the thermal stability of silicone resins. A unique mode of improving thermal stability has been developed: hydrogen bonds are formed to prevent the movement of resin chains.
Kong Guoqiang et al. used silanol group-containing POSS to improve the thermal stability of silicone resins.
They studied the effect of different POSS addition amounts and addition methods on the thermal properties of silicone resins. The results showed that with the increase of the addition amount of trisilanol phenyl (P-POSS), the thermal properties of modified silicone resins first increased decreased later.


When the mass fraction of P-POSS is 5%, the modified silicone resin with good thermal properties can be obtained when the heating reaction method is adopted.
In addition, there have also been new developments in silicone-modified organic resins. Yang Fei et al. prepared silicone resin by siloxane monomer and silica sol, used to modify polyester, and obtained silicone-silica sol/polyester composite resin.
According to TG analysis, the higher the content of silicone resin, the better the thermal stability of the composite resin.


In addition, the amount of silicone resin has a very important influence on the mechanical properties and hardness of the composite paint film: the increase of silicone resin increases the hardness of the paint film and improves the adhesion, but at the same time reduces its flexibility.
Chen Yanan used silica sol modified epoxy resin to prepare high-performance silicon-modified epoxy composite resin. According to SEM characterization, flocculation will occur when the system is in alkaline conditions.
The FT-IR analysis showed that the active hydroxyl groups in the silica sol successfully reacted with epoxy groups. A series of performance tests show that the emulsion has good thermal stability. When the content of silica sol is 10%, the composite resin has the best performance.