A NEW CYCLOLINEAR PHOSPHAZENE POLYURETHANE: SYNTHESIS FROM A DIISOCYANATE AND A BIS-SPIRO-SUBSTITUTED CYCLOTRIPHOSPHAZENE DIOL

New cyclolinear polymers from bifunctional organic molecules and cyclotriphosphazenes containing two reactive groups have been synthesized. The reaction between 2,2-bis(4-hydroxyphenoxy)-bis[spiro(2',2 "-dioxy-1',1 "-biphenylyl)] cyclotriphosphazene 3, obtained by the reaction of 2,2-bis(4-methoxyphenoxy)- bis[spiro(2',2 "-dioxy-1',1 "- biphenylyl)] cyclotriphosphazene 2 with BBr3/H2O, and hexamethylene diisocyanate (HDI) led to the new cyclotriphosphazene containing polyurethane 4. The structures of 4 and also of compounds involved in its synthesis were investigated by P-31, C-13 and H-1 NMR, infrared spectroscopy, mass spectrometry and elemental analysis. The molecular weight was determined by SEC analysis. The thermogravimetric behaviour of 4 was compared with that of a similar polyurethane containing a cyclotriphosphazene as a pendant group. The results show that the incorporation of phosphorus atoms into the backbone improves the thermal properties of the polymers.