Reactivities of Dialkyl Dithiol Mesaconates in Radical Copolymerization with Styrene

Nine novel types of dialkyldithiol mesaconates (DRTM, M₁) were synthesized and copolymerized with styrene (Ma) in tetrahydro-furan at 60 °C in order to clarify the polymerization behavior of DRTM and the substituent effects on the copolymerization. From the results obtained, the monomer reactivity ratio r₁, r₂ and Q₁, e₁ values were determined. It was found that the relative reactivities l/r₂ of DRTM toward an attack by polystyryl radical were correlated only by the polar substituent constant σ? of the alkyl group in DRTM, but not by the steric substituent constant E, in Taft's equation: log (l/r₂) = σ?σ? + ΔE_s. It was also observed that the Q₁ and e₁ values for DRTM were correlated by Taft's σ? constant. The number-average molecular weights of the DRTM-ST copolymer were found to be between 5.0 × 10³ and 1.2 × 10⁴.