| abstract |
A BrønstedLowry 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 (I) where: M is tantalum (Ta), vanadium (V) or niobium (Ni); each R 1 is independently H, OR 6 , F, Cl, Br, I or alkyl, where R 6 is H or alkyl; R 2 , R 3 , R 4 and R 5 are independently H, F, Cl Br, I, alkyl or aryl, or two or more of R 2 , R 3 , R 4 and R 5 on a same benzene ring form a bicyclic, tricyclic or tetracyclic moiety with the benzene ring, with the proviso that all of R 2 , R 3 , R 4 and R 5 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. |