Poly (styrene-alt-maleic anhydride) (SMA) may be conveniently used as an intermediate in preparing functional polymers since active agents containing amino or hydroxy groups can be linked to it via ring-opening reaction. In this study, SMA was reacted with 4-aminophenol (AP) to obtain SMA-AP conjugate. The glass transition temperature (218 degreesC) of the polymer was higher than that of SMA (202 degreesC) due to intermolecular hydrogen bonding. The polymer under-went thermal degradation in two steps where the initial weight loss began to occur at about 230 degreesC due to the formation of acid anhydride bonds with loss of water. SMA-AP exhibited bactericidal activity against E. coli and S. aureus, but it did not show any inhibition zone against the bacteria cells. No free AP was detected from the polymer incubated under similar conditions. Therefore, it was concluded that SMA-AP may be a bactericidal material by itself and its bactericidal activity may last for a fairly long period of time under neutral conditions. (C) 2002 Elsevier Science B.V. All rights reserved.