ABSTRACT:The reaction between a dihydroxyphenoxycyclotriphosphazene containing allylic functions, 3, and hexamethylene-1,6-diisocyanate (HDI) leads to a new cyclotriphosphazene-substituted polyurethane 4. The structures of both classes of compounds involved in that synthesis were investigated by 31 P-, 13 C-, and 1 H-NMR, infrared, and mass spectrometries, size-exclusion chromatography, and elemental analysis. The thermal behavior of 4 was investigated and compared to that of hexaphenoxycyclotriphosphazene, N 3 P 3 (OC 6 H 5 ) 6 , and of a polyurethane synthesized from 1,3-bis(hydroxy)benzene and HDI. The free-radicalpromoted grafting of 4 onto the polyethylene surface is described. The resultant surface was studied by ATR-IR, XPS, and contact-angle techniques.