Copolymerization of ethylene and halogenated styrenes using scandium catalysts

Abstract Copolymerization of ethylene (E) and halogenated styrenes is screened by half-sandwich scandium catalyst 1 and constrained geometry scandium catalysts 2–4. The methyl-substituted N-heterocyclic carbene fluorenyl catalyst 3 initiates the E copolymerization with para-fluorostyrene (pFSt), para-chlorostyrene (pClSt) and para-bromostyrene (pBrSt) to pseudo-random copolymers with an incorporation level of up to 46.3 mol%, 45.1 mol% and 37.5 mol%, respectively. Increasing reaction temperatures from 20 to 60 oC results in an increment of E/pFSt copolymerization activity from 5.64×105 to 8.10×105 g molSc-1h-1. In contrast, a higher temperature dramatically depresses the E/pClSt copolymerization (4.86×105 g molSc-1h-1 at 20 oC vs 0.90×105 g molSc-1h-1 at 60 oC). At 20 oC, the E/pBrSt copolymerization only affords a little pure polyethylene, and the E-pBrSt copolymer with 37.5 mol% pBrSt is obtained at 0 oC. The pseudo-random copolymers of E and halogenated styrenes give one glass transition temperature and decomposition temperature on DSC and TGA curves.