Oxazoline-functionalized polypropylenes were synthesized by using the rac-Et[1-Ind](2)ZrCl2/MAO catalyst system. The used comonomers were 2-(9-decene-1-yl)-1,3-oxazoline (R-Ox1), 2-(9-decene-1-yl)-4,4-dimethyl-1,3-oxazoline (R-Ox2), and 2-(4-(10-undecene-1-oxy)phenyl)-1,3-oxazoline (R-Ox3). The oxazolines reduce the catalyst activity in the order R-Ox3 > R-Ox1 > R-Ox2. By the addition of triisobutylaluminum (TIBA), the catalyst poisoning is reduced and is most pronounced in the R-Ox1- and R-Ox2-containing systems. The oxazoline-containing copolymers were melt blended with carboxytic acid end-functionalized polystyrene (PS-COOH) at 200degreesC. Strong changes in the morphology of the reactive blends compared to the nonreactive blends, especially the cocontinuous morphology in a poly(propylene-co-R-Ox3)/PS-COOH blend, indicate the usefulness of the modified copolymers in the reactive blending processes. (C) 2002 Wiley Periodicals, Inc.