The thermolysis of labile 1,2-bis(trimethylsilyloxy)tetraphenylethane groups pendant along polystyrene chains in the presence of various vinyl monomers leads to the direct synthesis of graft copolymers. Depending on the monomer chosen, the polymerization temperature, and the number of active sites by the macroinitiator molecule, crosslinked or total soluble graft copolymers can be prepared. Several conditions were studied in order to attain soluble polystyrene-g-poly(methyl methacrylate) copolymers under a controlled polymerization mechanism. (C) 2002 John Wiley & Sons, Inc.