Abstract: Phenolic impurities are removed from polyaryloxyphosphazenes by extracting a solution of the crude polyaryloxyphosphazene with an aqueous lower alcohol alkali metal base solution such as aqueous methanolic sodium hydroxide.

Abstract: Polymer-grade cyclic phosphonitrilic halide trimer can be obtained by (i) reacting ammonium halide with phosphorus pentahalide in an inert solvent containing pyridine, substituted pyridines or mixtures thereof or hydrogen halide complexes thereof, (ii) washing the solvent phase with an aqueous alkali metal hydroxide and (iii) crystallizing cyclic trimer and/or distilling the cyclic trimer to obtain polymer-grade trimer.

Abstract: Cyclic phosphonitrilic halides are formed rapidly and in high yield in a controllable multi-step process including the step of reacting a nitrogenous base (e.g. pyridine) with a phosphorus tetrahalide (e.g. phosphorus pentachloride) in a suitable inert liquid reaction medium (e.g. monochlorobenzene) to form a complex and in a subsequent step reacting this complex with an ammonium halide (e.g. ammonium chloride) at a temperature above about 90.degree. C. up to the reflux temperature of the reaction medium to form cyclic phosphonitrilic halides, mainly trimer.

Abstract: Cyclic phosphonitrilic halide trimer is made in high yield and at a rapid rate by adding NH.sub.3 or ammonium halide to a pyridine-hydrogen halide complex and adding phosphorus pentahalide and a solvent for the trimer (e.g. monochlorobenzene) and heating the mixture to above 90.degree. C. to form trimer which dissolves in the solvent and then separating the trimer-solvent phase from the residue phase of pyridine-hydrogen halide complex and recovering trimer from the solvent phase and recycling the pyridine-hydrogen halide phase to a subsequent procedure conducted in the same manner. The process can also be adapted to produce linear species in high yield also.

Abstract: Polyetheroxy-substituted polyphosphazenes useful in making solid electrolytes are purified by dissolving the impure polyphosphazene in water at a low temperature (e.g. below 40.degree. C.) and heating the water solution to a temperature high enough to cause the purified polyphosphazene to precipitate (e.g. above 50.degree. C.).

Abstract: Polymer-grade cyclic phosphonitrilic chloride trimer can be obtained from crude cyclic polyphosphonitrilic chlorides by forming a solution of the crude cyclics, water washing the solution, distilling solvent to form a hot concentrate, cooling to form a precipitate and distilling the precipitate to form polymer-grade trimer.

Abstract: Cyclic phosphonitrilic chloride trimer suitable for polymerization to light colored, high molecular weight, linear polyphosphonitrilic chloride can be made by (1) reacting PCl.sub.5 and NH.sub.4 Cl in an inert solvent (e.g. monochlorobenzene) to form a solution of a low molecular weight linear and cyclophosphonitrilic chlorides, (2) evaporating solvent to form a concentrate, (3) adding water and cooling the mixture to precipitate cyclic trimer, (4) separation of the trimer precipitate and (5) distillation of the separated trimer.