This article presents the development and characterization of transparent poly(styreiie-r-maleic anhydride) (SMA)/alumina nanocomposites for potential use in optical applications. Chemically treated spherical alumina nanoparticles were dispersed in an SMA matrix polymer via the solution and melt-compounding methods to produce 2 wt % nanocomposites. Field emission scanning electron microscopy was used to examine the nanoparticle dispersion. When the solution method was used, nanoparticle reagglomeration occurred, despite the fairly good polymer wetting. However, through the coating of the alumina nanoparticles with a thin layer (ca. 20 nm) of low-molecular-weight SMA, reagglomeration was absent in the melt-compounded samples, and this resulted in excellent nanoparticle dispersion. The resultant nanocomposites were semitransparent to visible light at a 2-mm thickness with improved UV-barrier properties. Their impact strengths, tensile strengths, and strains at break were slightly reduced compared with those of their neat resin counterpart, whereas a small enhancement in their moduli was achieved. (C) 2007 Wiley Periodicals, Inc.