| Abstrakt: |
Living cationic polymerization of N-vinylcarbazole (NVC) has successfully been achieved with iodine initiator in both polar (CH2Cl2) and less polar (CH2Cl2–CCl4, 1/1, v/v) solvents at -50°C. Under these conditions, the molecular weight of polymers increased linearly with increasing conversion, and it further increased on addition of a new-monomer feed to a completely polymerized solution. The number-average molecular weights of the polymers produced in a CH2Cl2–CCl4(1/1, v/v) mixture were in fair agreement with theoretical values based on the assumption that one initiator molecule yields one polymer chain. At a higher temperature (-15°C), living poly(NVC) could be obtained only in a nonpolar solvent (toluene). Polymerizations by oxo acids (CF3COOH, CH3SO3H, and CH3COClO4) or BF3OEt2failed to give living polymers even at low temperatures. It was concluded that long-lived propagating species are generated specifically by iodine initiator from a monomer giving a stable carbocation with an electron-donating substituent. |
