What is "polysilazane"

Polysilazanes are polymers in which silicon and nitrogen atoms alternate to form the basic backbone. Since each silicon atom is bound to two separate nitrogen atoms and each nitrogen atom to two silicon atoms, both chains and rings of the formula [R1R2Si–NR3] occur. R1-R3 can be hydrogen atoms or organic substituents. If all substituents R are H atoms, the polymer is designated as Perhydropolysilazane, Polyperhydridosilazane or Inorganic Polysilazane ([HSi–NH]). If hydrocarbon substituents are bound to the silicon atoms, the polymers are designated as Organopolysilazanes. Molecularly, polysilazanes [R1R2Si–NH] are isoelectronic with and close relatives to Polysiloxanes [R1R2Si–O] ( silicones).