X-ray photoelectron spectroscopic studies of polyquinazolones. An assessment of the degree of cyclization

Abstract

Prepolymers of polyquinazolone have been prepared from 4,4′-diaminodiphenyl-3,3′-dicarboxylic acid and aromatic diacetoamido compounds by melt condensation. Optimum preparative conditions were established for each individual system on the basis of reduced viscosity and thermogravimetry (TG) results. The soluble prepolymers were converted to the quinazolone structure by thermal cyclization under two heating programmes. A significant amount of uncyclized carboxylic groups have been identified by X-ray photoelectron spectroscopy (XPS). Quantitative measurements of the C=O/COOH ratio at the surface of the resultant polymers have been carried out by XPS, which provide a reliable measure of the degree of cyclization. Comparison of XPS results with TG data indicates a direct correlation between degree of cyclization on the polymer surface and thermooxidative stability of the bulk polymer.