Characterization of a series of phenyl-capped vinyl-terminated oligomers of styrene

Low molecular weight (MW) polystyrenes were synthesized by radical polymerization in the presence of catalytic chain-transfer agents. Synthetic conditions are controlled to produce molecules containing one methyl group at one end as well as a double bond at the other end, capped with a phenyl group. Individual oligomers were separated by liquid chromatography, and the properties were analyzed using NMR, ultraviolet–visible (UV–vis) spectroscopy, and size exclusion chromatography with light scattering. The UV–vis spectra, proton NMR spectra, and differential refractive-index increments exhibit an MW dependence of up to six–eight monomer units. The obtained dependencies can be used for precise characterization of the molecular weight distribution of polystyrene obtained by catalytic chain transfer. The double-bonded end groups were found to be exclusively in the transconfiguration for all oligomers.