Organopolysilazane is a new type of inorganic-organic hybrid polymer with Si-N bonds as the main chain and organic groups as side chains. As a high-performance ceramic precursor and functional material intermediate, its unique molecular structure endows it with excellent high-temperature resistance, oxidation resistance, corrosion resistance and film-forming properties. Different from traditional organosilicon polymers, it can be converted into dense silicon-based ceramics (such as Si₃N₄, SiO₂) at low temperatures, making it a core raw material in high-end coatings, ceramic matrix composites and other fields. With the improvement of downstream high-end manufacturing requirements for material performance, the molecular structure optimization and synthesis process upgrading of organopolysilazane have become the core direction of industrial development.
The core advantage of organopolysilazane stems from its Si-N main chain structure and adjustable side chain substituents. The bond energy of Si-N bond (435 kJ/mol) is much higher than that of Si-O bond, endowing it with excellent high-temperature resistance, which can maintain structural stability above 800℃ and a maximum temperature resistance of up to 1500℃. At the same time, it has good chemical corrosion resistance, which can resist the erosion of strong acids, strong alkalis and organic solvents. The introduction of side chain organic groups (such as methyl, vinyl, phenyl) can flexibly adjust the solubility, film-forming property and reactivity of the product. Methyl-substituted type focuses on film compactness, vinyl-substituted type improves crosslinking activity, and phenyl-substituted type enhances high-temperature resistance and radiation resistance, adapting to the needs of different application scenarios.
At present, the mainstream synthesis processes of organopolysilazane mainly include ammonolysis, aminolysis and hydrosilylation. The ammonolysis method uses chlorosilane as raw material and undergoes substitution reaction with ammonia gas to generate organopolysilazane. The process is simple and the cost is low, but the product has wide molecular weight distribution, insufficient purity, and is prone to generate ammonium chloride impurities, which affect product performance. The aminolysis method uses organic amines instead of ammonia gas, which can prepare organopolysilazane with more regular structure and improved product purity, but the reaction rate is slow, there are many by-products, and the subsequent purification is difficult. The hydrosilylation method uses silanes containing Si-H bonds and amines containing unsaturated bonds as raw materials to react under the action of catalysts. The product has controllable structure and uniform performance, but the catalyst cost is high and large-scale production is difficult.
Process upgrades focus on three major directions: purity improvement, structural controllability and green efficiency. By optimizing the raw material purification process, high-purity chlorosilane and organic amine raw materials are used to remove impurity interference and improve the product purity to more than 99.5%; new composite catalysts are developed to accelerate the reaction rate of aminolysis and hydrosilylation, reduce the generation of by-products, and realize precise control of molecular weight and side chain structure. At the same time, solvent-free synthesis processes are promoted to replace traditional organic solvent systems, reducing volatile organic compound emissions and meeting the requirements of green chemical industry. In addition, the application of continuous production process improves production efficiency, reduces production costs, and promotes the transformation of organopolysilazane from laboratory synthesis to large-scale and high-end production, adapting to the needs of more high-end scenarios.