Regioirregular propene insertion in polypropenes synthesized with unbridged bis(2-aryl)indenyl zirconium dichloride catalysts: Implications on activity
S. Lin et Rm. Waymouth, Regioirregular propene insertion in polypropenes synthesized with unbridged bis(2-aryl)indenyl zirconium dichloride catalysts: Implications on activity, MACROMOLEC, 32(25), 1999, pp. 8283-8290
Catalysts of the type bis(2-(3,5-R2C6H3)indenyl)zirconium dichloride/MAO (2
, R = H; 3, R = CF3) were investigated for regioregularity of monomer inser
tion in bulk propene polymerization and compared to the isospecific catalys
t rac-(ethene)bis(indenyl)zirconium dichloride/MAO (1). The amount of regio
irregular propene insertions were in the range of 0.1-0.5 mol % and followe
d the trend 2 < 3 < 1. Comparison of polymerizations in the presence and ab
sence of hydrogen revealed a 4-10-fold increase in productivity for catalys
ts 2 and 3 in the presence of hydrogen but only a slight increase in produc
tivity with 1. For catalysts 2 and 3, only 2,1-erythro internal regioerrors
were observed, whereas 1 produced both 2,1-erythro and 2,1-threo misinsert
ions. Evidence for ethene insertion following a 2,1-regioerror was obtained
by copolymerization of (C2H4)-C-13 with propene using catalyst 3. The corr
elation between number of 2,1-misinsertions and catalyst activity is discus
sed.