NOVEL MISCIBLE BLENDS OF ETHERIC POLYPHOSPHAZENES WITH ACIDIC POLYMERS

The miscibility of inorganic polyphosphazenes with organic polymers is investigated. The presence of acidic or proton-donating functional groups on the organic polymer is shown to increase the miscibility of the organic polymer with polyphosphazenes containing ethylene oxide side chains. Thus, poly(vinylphenol) (PVPh) is miscible over the entire composition range with poly[bis(methoxyethoxyethoxy)phosphazene] (MEEP) and with poly[bis(methoxyethoxyethoxyethoxy)phosphazene] (MEEEP) but is not miscible with poly[bis(trifluoroethoxy)phosphazene] or with poly[bis(phenoxy)phosphazenel. Differential scanning calorimetry is used to determine the glass transition temperatures of these blends. The shape of the T(g)-composition curves is found to be sigmoidal and is very similar to that reported for blends of polystyrene and poly(vinyl methyl ether). The enthalpy of mixing is determined for low molecular weight model compounds of the polymers. These results show that the interactions between the phenol and the etheric phosphazenes are strong and exothermic, whereas the interactions between the phenol and the trifluoroethoxy and phenoxy phosphazenes are endothermic. Interactions between PVP hand MEEP are also observed via infrared studies. Preliminary studies reveal miscibility of MEEP with a number of styrene or methyl methacrylate copolymers when a small amount of acidic comonomer is introduced.