The compressive strengths of micron-sized, cross-linked poly(styrene-divinylbenzene) particles synthesized by conventional radical copolymerization (70 degrees C and nitroxide (TEMPO) -mediated radical copolymerization (125 degrees C in aqueous micro-suspension have been measured. In the conventional system, the breaking energies and the compressive strengths of the particles (after removal of unreacted monomer) remained approximately constant from low to high conversion, whereas in the NMP system, both quantities increased close to linearly with conversion. The results suggest that the network formation is more homogeneous in the NMP system than in the conventional system. (c) 2007 Elsevier Ltd. All rights reserved.