Plots used to determine the co-polymerization parameter (reactivity ratio) for the co-polymerization of HCBI and styrene by the methods of Mayo-Lewis. The conditions include bulk polymerization and AIBN at 65 °C. All three methods yield co-polymerization parameters r HCBI/styrene = 0.79 ± 0.3 and r styrene/HCBI = 0.046 ± 0.05, indicating the formation of statistical co-polymers with a preference for the incorporation of HCBI over styrene into the growing polymer chain. The data are shown in Supplementary Table 1.