Graft polymerization of ethyl acrylate and n-butyl acrylate onto surface of polypropylene (PP) beads (diameter: 3.2 mm) were carried out by using a redox system composed of triethylborane (Et3B) and molecular oxygen in air. The amounts of the grafted polymers increased by prolonging a period of soaking PP beads in a solution of Et3B in hexane, a less polar solvent of which affinity with PP would be higher than that of tetrahydrofuran, a highly polar solvent. These results implied that the present graft polymerization involved: (1) interpenetration of Et3B into the surface area with the aid of hexane as a solvent, (2) its aerobic oxidation to generate a radical species, (3) abstraction of proton from PP by the radical species, and (4) initiation of polymerization from the resulting radical on the PP surface. Besides the acrylates, acrylic acid, and glycidyl methacrylate were also grafted onto the surface of PP to endow it with carboxyl and epoxy moieties, respectively. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6163-6167, 2009