A good way of achieving compatibility in polymer blends of poly(styrene-co-acrylonitrile) (S/AN) and bisphenol A polycarbonate (PC) is the chemical modification of S/AN in the melt. A catalyzed reaction of the nitrile groups with a substituted 2-amino alcohol or 2-amino phenol resulted in a conversion of nitrile groups of 55-75% in 60 min. The introduced heterocyclic structures were ethyl hydroxymethyl oxazoline (EHMOXA) and benzoxazole (BenzOXA), respectively. The use of dibutyltin oxide as a catalyst led to the highest efficiency. The modified polymer was characterized by Fourier transform infrared and NMR spectroscopy, elemental analysis, and reactions with organic acids and anhydrides. The modified S/AN showed good technical compatibility (single glass-transition temperature) with PC in blends made from solution and from the melt. All blends were characterized with oscillating rheometry and differential scanning calorimetry. Rheological measurements showed that EHMOXA-S/AN reacted with PC and had crosslinked structures, whereas BenzOXA-S/AN showed compatibilization without any (crosslinking) reaction. The melt blends of BenzOXA-S/AN and PC showed a downward shift in the complex viscosity due to the influence of the BenzOXA group. (C) 2003 Wiley Periodicals, Inc.