To improve the interfacial adhesion between poly(vinyl chloride) (PVC) and bamboo flour in PVC/bamboo flour composites, a novel coupling agent, poly(styrene-co-maleic anhydride)-block-poly(styrene-coacrylonitrile) {P[(SMA)-b-(SAN)]}, was synthesized through living free-radical polymerization in a one-pot reaction. P[(SMA)-b-(SAN)l was synthesized by a nitroxide-mediated polymerization technique in the presence of 2,2,6,6-tetramethylpiperidin-l-oxyl with azobisisobutyronitrile. The conversion of maleic anhydride (>99%) and styrene (>65%) was relatively high and yielded P[(SMA)-b-(SAN)l with a narrow molecular weight distribution (weight-average molecular weight/number-average molecular weight <138). PVC was blended with bamboo flours in the presence of the synthesized coupling agent with a two-roll mill. P[(SMA)-b-(SAN)] was added to the PVC matrix at a concentration of 55 or 20 wt%. As the content of P[(SMA)-b-(SAN)] in the wood-polymer composite increased, improved morphological and mechanical behaviors were observed. (c) 2008 Wiley Periodicals, Inc.