| abstract |
A Brønsted-Lowry acid initiator system for cationic polymerization of an ethylenically unsaturated monomer involves an initiator having a structure of Formula (I) in an anhydrous polymerization medium:where: M is tantalum (Ta), vanadium (V) or niobium (Nb); R1, R2, R3 and R4 are the same or different and are independently H, F, Cl, Br, I, alkyl or aryl, or two or more of R2, R3, R4 and R5 on a same benzene ring are taken together to form a bicyclic, tricyclic or tetracyclic moiety with the benzene ring, with the proviso that all of R1, R2, R3 and R4 on the same benzene ring are not H; L is absent or a molecule that coordinates to H+; and, x is 0 when L is absent, or x is 0.5 or more when L is present. |