Trichloroethoxy-substituted polyphosphazenes: Synthesis, characterization, and properties

High polymeric organophosphazenes have been synthesized with trichloroethoxy side groups either as the sole substituents or as cosubstituents with trifluoroethoxy, phenoxy, or methoxyethoxyethoxy groups. Initially, small-molecule model compound studies were carried out between sodium trichloroethoxide and hexachlorocyclotriphosphazene at ambient temperature to yield the fully substituted product hexakis(trichloroethoxy)cyclotriphosphazene as a prelude to the synthesis of high polymeric trichloroethoxy homo-and cosubstituted phosphazenes. The cyclic trimeric and polymeric species were characterized by ¹H and ³¹P NMR, GPC, and DSC techniques. Physical property comparisons were made with the long-established elastomers that contain both trifluoroethoxy and longer chain fluoroalkoxy side groups by the use of DSC, TGA, and limited oxygen index tests. The introduction of trichloroethoxy side groups further improves the resistance of these polymers to combustion.