POLYPHOSPHAZENE MOLECULAR COMPOSITES .1. INSITU POLYMERIZATION OF TETRAETHOXYSILANE

Composite materials have been prepared by combining polyphosphazene polymers with a silicon oxide precursor, tetraethoxysilane (TEOS), which is polymerized in situ. Poly[bis(methoxyethoxyethoxy)-phosphazene] (MEEP), a polymer that flows at room temperature, forms a clear, flexible, free-standing film when TEOS is polymerized in situ. The storage moduli (E) for the MEEP/TEOS composites exceed 10(9) dyn/cm2 and the shore A hardness obtained for these materials is ca. 83. In contrast, the corresponding values for the amorphous homopolymer were so low that they could not be measured at room temperature. Preliminary evidence indicates that the etheric side groups of the MEEP are adsorbing to the silicate network and pseudo-cross-linking results. Improved mechanical properties of a (fluoroalkoxy)phosphazene, partially hydrolyzed poly[bis(trifluoroethoxy)phosphazene] (TFEP-OH), were evident in that a rubbery plateau region above (T1) is observed in the storage modulus. The oxide particles are thought to be retarding the movement of the polymer crystallites.