The Relative Reactivities of Alkyl Acrylates in Their Radical Copolymerizations

In order to clarify the effect of the alkyl groups in alkyl acrylates (RA) on their reactivities to the attack of a radical, the copolymerization of RA (M2) with styrene (M1) has been carried out at 60°C. From the results obtained, the monomer reactivity ratios and the Q2 and e2 values were determined. It was found that the relative reactivities (1/r1) of RA to a polystyryl radical were correlated only by the polar substituent constant (σ*) of the alkyl group in RA, not by their steric substituent constant (Es) in Taft’s equation: log(1⁄r1)=ρ*σ*+δEs According to the above equation, the ρ* and δ values were obtained as 0.56 and 0, respectively. It was also observed that the Q2 and e2 values for RA were correlated by Taft’s σ* substituent constant.