Catalytic preparation of soluble poly(dichlorophosphazenes)

A process for the preparation of soluble polyhalophosphazene polymer consisting essentially of recurring structural units represented by the formula [X.sub.2 PN] and having an intrinsic viscosity of about 0.01 to about 3.0 dl/g (benzene, 30.degree. C), said polymer being soluble in benzene, toluene, chlorobenzene, and dichlorobenzene, which comprises heating at least one cyclic oligomer represented by the formula (X.sub.2 PN).sub.m where m is 3-7, wherein X is a halogen selected from the group consisting of F, Cl, and Br and all of the X's are not required to be identical, at temperatures of about 130.degree. C to 220.degree. C in the presence of an effective amount of at least one catalyst which is selected from the group consisting of A and B and mixtures thereof wherein:

• Group A consists of metallic or quaternary ammonium salts in which the anion is represented by one of the following formulae:
• ##STR4## where R.sub.1 is a monovalent member selected from the group consisting of polyhaloalkyl, where the halogen is F, Cl or mixtures thereof, perfluoroaryl and perchloroaryl;
• R.sub.2 is a monovalent member selected from the group consisting of F, Cl, lower alkyl (C.sub.1 -C.sub.5), aryl, substituted alkyl and substituted aryl with the proviso that R.sub.2 is not halogen when bonded to ##STR5## and the metal of the salt is a metal selected from the group consisting of Li, Na, K, Mg, Ba, Hg, Ag, Mn and Zn;
• Group B consists of at least one acid selected from the group consisting of acids represented by the following formulae:
• ##STR6## H.sub.3 PO.sub.4 and its dehydrated derivatives and wherein R.sub.1 and R.sub.2 are as defined in Group A.