I. Definition and Structural Characteristics of Polysilazanes
Polysilazanes (PSZs) are a class of inorganic-organic hybrid polymers with a main chain composed of alternating silicon (Si) and nitrogen (N) atoms, possessing the general chemical formula [R₁R₂Si-NR₃]ₙ (where R₁~R₃ are hydrogen or organic groups). The Si-N bond energy in their structure is as high as 355 kJ/mol, endowing the materials with excellent thermal stability and chemical inertness. Based on the type of substituents, polysilazanes can be divided into all-hydrogen polysilazanes (PHPS, all substituents are hydrogen) and organopolysilazanes (OPSZ, containing hydrocarbon substituents). The latter can have its performance further improved through modification.

II. Core Properties and Applications of Polysilazane
High Temperature Resistance and Ceramicization Potential:
Polysilazane can be converted into Si₃N₄, SiC, or SiCN ceramics through high-temperature pyrolysis (1000~1500℃) in an inert atmosphere. Theoretically, it can withstand temperatures up to 1800℃, and its hardness after curing reaches 8H or higher. This characteristic makes it an ideal precursor for aerospace engine components, high-temperature coatings, and ceramic matrix composites.

Chemical Stability and Protective Properties:
The Si-N bond is highly stable against acids, alkalis, salt spray, and high-energy radiation, with a dielectric strength ≥10V/mm. Polysilazane coatings can withstand 2400 hours of condensate corrosion testing. After modification, the water contact angle exceeds 120°, achieving superhydrophobicity and self-cleaning functions, making it widely used in metal corrosion protection, industrial coating, and electronic packaging.

Breakthroughs in Optoelectronics and New Energy:
All-hydrogen polysilazane (PHPS) exhibits outstanding performance in the optoelectronic field. It can be used to prepare dielectric layers, barrier layers, and optical coatings. Its converted silica layer has a visible light transmittance >95% and excellent gas barrier properties. In solar cells, PHPS, used as an encapsulation layer, can significantly improve anti-aging properties and extend the lifespan of flexible perovskite cells by over 400 hours.

III. Technological Challenges and Development Prospects
Despite the excellent performance of polysilazanes, their high reactivity makes storage and transportation difficult, and the synthesis process is complex with challenging product control. With breakthroughs in modification technologies (such as elemental doping and blending modification), the application potential of polysilazanes in extreme environment materials, flexible electronics, and structural functional composite materials continues to be realized, and the market is expected to maintain a high growth rate.