Functionalization of poly(organophosphazenes) .6. Substituent effect on the grafting reaction of maleic anhydride onto phenoxy-substituted phosphazene polymers

In this paper we describe the solution functionalization reaction of six phenoxy-substituted poly(organophosphazenes) with maleic anhydride and the effect of the phosphazene substituents on the overall grafting yield of anhydride moieties. It was found that the phosphazene polymer substituted with 4-ethylphenoxy groups is the most reactive of the whole series of exploited materials, while that bearing 4-t-butylphenoxy groups is the most inert one. This experimental reactivity trend observed in the grafting process is accounted for on the basis of both thermodynamic and steric factors.