Cationic Polymerization of Vinyl Monomers Initiated by Carbon Black Surface

Abstract

The polymerization of vinyl monomers initiated by carboxyl groups on the surface of carbon black has been investigated. Channel blacks were found capable of initiating the cationic polymerization of vinyl monomers such as vinyl ethers, indene, and acenaphthylene but unable to initiate that of styrene and vinylpyridines. The rate of polymerization, Rp, of isobutyl vinyl ether (IBVE) initiated by Carbolac 1 in polar solvent (CCl4/C6H5NO2=50 v/v%) is expressed by the following equation: Rp=const [IBVE]2 [Carbolac 1]. The features are explained on the basis of a conventional cationic mechanism. The overall activation energy is estimated to be 27 kcal mol−1. This value is larger than that of the polymerization of IBVE in nonpolar solvent (CCl4). In addition, during polymerization, the polymer is grafted onto the surface of carbon black and the carbon black obtained from the reaction gives a stable colloidal dispersion in good solvents for the polymer. The grafting sites of the polymer were found to be carboxyl groups present on the surface.