CONTROLLED FORMATION OF CARBOXYLIC-ACID GROUPS AT POLYPHOSPHAZENE SURFACES - OXIDATIVE AND HYDROLYTIC ROUTES

Two methods have been developed for the controlled formation of carbox ylic acid units at the surfaces of aryloxyphosphazene high polymers. T he first involves a permanganate-induced oxidation of p-methylphenoxy side groups, with the surface density of carboxylic acid units being c ontrolled by the ratio of p-methylphenoxy to phenoxy groups along the polymer chains. The second approach involves a base-induced hydrolysis of carboxylate ester functions at the para-positions of surface arylo xy side groups. In this method the surface density of carboxyl units i s controlled by the reaction conditions, especially by the temperature and the solvent for the base. The same ester functions were converted to alcohol moieties by surface reductions using lithium aluminum hydr ide in diethyl ether. The surface structures before and after these re actions were studied by a combination of contact angle measurements, X -ray photoelectron spectroscopy, scanning electron microscopy with X-r ay microanalysis, and ATR-IR spectroscopy.