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 intrisic 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 at least one catalyst which is selected from the group consisting of phosphazene derivatives consisting of the reaction product formed by reacting (1) at least one cyclic oligomer represented by the formula (X.sub.2 PN).sub.m in which X represents a halogen selected from the group consisting of F, Cl and Br are not all of the X's are required to be the same, and m is an integer from 3-7, with at least one salt (2) of an anion selected from the group consisting of metallic or quaternary ammonium salts in which the anion is represented by one of the following formulae:

• [M.sup.r Z.sub.r+t ].sup.-t, I.sup.-, [NCS].sup.-, PF.sub.6.sup.-, BF.sub.4.sup.-, and [QX'.sub.r-x ].sup.-(2-x)
• where Z is F or Cl;
• M is selected from the group consisting of metals and non-metals from Groups Ia, Ib, IIa, IIb, Vb, and VIII of the Periodic Table, Al, Mo, Re, Sn, Zr, As, Sb, Ti, Pb, Mn, and Th, with the proviso that when the anion is iodide the cation is selected from alkali, alkaline earth and quaternary ammonium, r is the valence of Metal M;
• t is an integer designating the magnitude of the negative charge of the complex ion [M.sup.r Z.sub.r+t ].sup.-t ;
• and Q is a metal selected from the group consisting of Hg, Cd, and Zn and X' is either Br, or I, and x is 0 or 1;
• and ##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 then bonded to ##STR5## whereby at least one X in the compound (X.sub.2 PN).sub.m is replaced, and all of the displacing groups are not required to be the same.