The free-radical polymerization of styrene with p-nitrobenzyl triphenyl phosphonium ylide as an initiator in dioxane at 80 +/- 1 degrees C in a dilatometer under a nitrogen atmosphere for 150 min resulted in a syndiotactic polymer, as evidenced by IR, H-1 NMR, and C-13 NMR spectroscopy. A H-1 NMR spectrum showed methylene protons as triplets; C-13 NMR signals of the phenyl ipso carbons were used for the determination of the tacticity. The system followed ideal kinetics. Gel permeation chromatography data were used evaluate the weight-average molecular weight. The overall activation energy was 47 kJ/mol. Electron spin resonance spectroscopy confirmed the initiation by the phenyl radical obtained by the dissociation of the ylide and the free-radical mode of polymerization. Differential scanning calorimetry studies showed the glass-transition temperature of the polymer to be 342 K. (c) 2005 Wiley Periodicals, Inc.