and redox characteristics to this end we will prepare and study triarylverdazyl radicals having ar p me 2 nc 6 h 4 or ar p o 2 nc 6 h 4 see fig8 as a means of assessing how polymerization behavior is affected by electronic effects analogous radicals lacking the carbonyl group will be studied if necessary steric factors play a significant role in affecting the nitroxide polymer bond through kinetic and or thermodynamic stabilization of the stable free radical similar effects in analogous verdazyl chemistry are anticipated to this end we will prepare verdazyls bearing bulkier substituents in the 1 3 5 positions such as t butyl or ortho disubstituted aryl e g mesityl as described above the polymerization runs are typically carried out under established sfrp conditions i e monomer x mol radical y mol initiator complementary to these studies will be the synthesis and study of so called u201c unimers u201d unimolecular precursors based on the stable radical coupled to one monomer unit that are upon dissociation capable of acting as both initiator and sfrp mediator nitroxide based u201c unimers u201d have been developed as single component initiator sfrp mediators and they also have been useful as model systems with which to study the nature of the radical polymer bond through studies of bond dissociation energies polymerization rates and byproduct formation the utility of unimers as model compounds is the primary motivation.