Polyorganosilazanes

Abstract Since dialkyldichlorosilanes yield almost entirely the cyclic trimeric and tetrameric silazanes by ammonolysis, a method had to be found to convert these oligomers into polymers. This can be done by heating the cyclic compounds with a catalytic amount of ammonium halides, preferably ammonium bromide or ammonium iodide, at 160°C. or more over a period of 6–8 hr. at atmospheric pressure. During this time ammonia is evolved, and there remains an oily polymer containing some silicon–halogen bonds. These are converted into SiN bonds by treating the raw polymer in ethereal solution with gaseous ammonia, yielding colorless waxy polysilazanes after evaporation of the solvent. The structures, spectra, properties, and reactions of these new polymers are discussed.