Functionalization of Poly[(alkoxy)phosphazenes]: Synthesis and Characterization of Poly(phosphazenes) Containing Hydroxyl Groups

Methoxy end groups mere cleaved from poly[bis(methoxyalkoxy)phosphazenes] {NP[(OCH2CH2)(m)OCH3](2)}(n), where m = 2 (2, MEEP) and m = 1 (3, MEP) by reaction with trimethylsilyl iodide to give silylated polymers {NP[(OCH2CH2)(m)OSiMe(3)](x) [(OCH2CH2)(m)OCH3](y)}(n) (x + y = 2; m = 2 (4), m = 1 (5)). The silylated polymers 4 and 5 were hydrolyzed in a second step to yield the alcohol-functionalized polymers {NP[(OCH2CH2)(m)OH](x) [(OCH2CH2)(m)OCH3](y)}(n) (m = 2 (6), m = 1 (7)). The structures of both classes of compounds were investigated by (31)p, C-13,.,and H-1 NMR and infrared spectroscopies. The correlation between the amount of ISiMe(3) and the percentage of resultant alcohol functions was established. This latter was estimated by first using H-1 NMR and secondly P-31 NMR. In the latter case use was made of the reaction of a bicyclophosphane 8 with the OH groups in 6 and 7, which leads to bicyclophosphorane-functionalized polymers. The two results are in agreement. The presence of the alcohol function was confirmed by the observation of cross-linking through the reactions of 6 and 7 with a diisocyanate and a polyphosphazene functionalized by succinic anhydride groups. This functionalization reaction induces chain degradation of the polymer as the percentage of alcohol functions increases.