Living cationic polymerization of isobutyl propenyl ether as β‐substituted vinyl ether

Abstract

AbstractIsobutyl propenyl ether [IBPE; CH3CH=CHOCH2CH(CH3)2] was polymerized with a mixture of hydrogen iodide and iodine (HI/I2 initiator) in n‐hexane at −40°C to yield living polymers with a nearly monodisperse molecular weight distribution (MWD) (M̄w/M̄n ≈ 1.1). The number‐average molecular weight (M̄n) of the polymers increased proportionally to IBPE conversion and further increased when a new monomer feed was added to a completely polymerized solution. The M̄n was controlled by the initial concentration of hydrogen iodide if the acid was charged in excess over iodine. In polymerization by iodine alone the M̄n of the polymers obtained in nonpolar solvents (n‐hexane and toluene) also increased with conversion, but their MWD was broader (M̄w/M̄n = 1.3–1.4) than in the HI/I2‐initiated systems under similar conditions. The iodine‐initiated polymerization in polar CH2Cl2 solvent, in contrast, led to nonliving polymers with a broad MWD (M̄n/M̄n = 1.6–1.8) and M̄n, independent of conversion. The living polymerization of IBPE was also compared with that of the corresponding isobutyl vinyl ether, to determine the effect of the β‐methyl group in IBPE.