Photoinitiated bulk polymerization of liquid crystalline thiolene monomers

The photoinitiated bulk polymerization of liquid crystalline thiolene monomers based on a phenyl benzoate core was investigated and the structure of the corresponding polymers analyzed. We show that polymerization occurs substantially in bulk, and can be initiated on demand by UV-irradiation. The liquid crystalline thiolene polymers exhibit a nematic mesophase, and the molecular weight, molecular weight distribution and overall conversion are characteristic for polymers obtained by a step-growth polymerization. Using NMR spectroscopy, we show that anti-Markovnikov structures are predominantly formed, with a small fraction of the structures displaying different configurations that can be attributed to thiol olefin addition - cooxidation processes or to homopolymerization of the olefinic moiety. The conversions of the thiol and vinyl groups were monitored using time-resolved, Raman spectroscopy and dissimilar partial reaction rates were observed.