Radical copolymerization of (−)-menthyl 2-acetamidoacrylate and styrene or methyl methacrylate near ceiling temperature

Radical copolymerization of chiral monomer, (−)-menthyl 2-acetamidoacrylate (1), with low ceiling temperature (Tc = 62.0 °C in [monomer] = 1.0 mol/L) and styrene or methyl methacrylate (MMA) has been studied near ceiling temperature (60 °C) and at the temperature lower than Tc (30 °C). Monomer reactivity ratios and Alfrey-Price Q and e-values of 1 are estimated to be r1 = 0.27, r2 = 0.067, Q = 3.0, and e = 1.2 at 30 °C, and r1 = 0.32 and r2 = 0.046 at 60 °C for the copolymerization of 1 (M1) and styrene (M2), suggesting an alternating tendency at both temperatures, whereas for the copolymerization of 1 (M1) and MMA (M2) r1 and r2 are estimated to be 2.9 and 0.019 at 30 °C, respectively, indicating longer sequence length of 1. Specific rotation and circular dichroism of the resulting copolymer indicate that styrene, in particular, is effectively incorporated into a helical copolymer structure at 60 °C and even only 25 mol% incorporation of the acetamidoacrylate unit in the copolymer induces the helix formation in solution.