The chemical modification of poly(vinyl alcohol) (PVA) was performed through oxidation followed by nucleophilic addition. PVA was oxidized by KMnO4 to form vinyl ketone units along the polymer backbone. The chemical modification of PVA was then conducted through the reaction of the carbonyl group of the vinyl ketone unit with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as a nucleophile. Through this approach, the phosphorous DOPO group was attached onto the carbon atom of the polymer main chain rather than onto the pendent hydroxyl groups of PVA. The formed DOPO-containing PVA showed improved thermal stability, organosolubility, and flame retardance. (C) 2003 Wiley Periodicals, Inc.