Metallocene/Borate-Catalyzed Copolymerization of 5-N,N-Diisopropylamino-1-pentene with 1-Hexene or 4-Methyl-1-pentene

Metallocene/borate catalysts, generated from zirconocene dimethyl compounds, L n ZrMe 2, and anilinium borate, [HNMe 2 Ph] + [B(C 6 F 5 ) 4 ] -, were used to copolymerize 5- N, N -diisopropylamino-1-pentene with 1-hexene and 4-methyl-1-pentene. The selected zirconocenes, bis(pentamethylcyclopentadienyl)zirconium(IV) dimethyl (Cp* 2 ZrMe 2 ) and rac -ethylenebis(4,5,6,7-tetrahydroindenyl)zirconium(IV) dimethyl ( rac -EB(THI)ZrMe 2 ), provided atactic and isotactic materials, respectively. The isotactic polymers produced were amorphous or crystalline depending of the monomer. The calculated reactivity ratios for the copolymerization of 5- N, N -diisopropylamino-1-pentene with 1-hexene and metallocene rac -EB(THI)ZrMe 2 indicate that this system approximates an ideal azeotropic copolymerization with r 1 = 1.11 and r 2 = 0.87. Estimates for the reactivity ratios for the copolymerization of 5- N, N -diisopropylamino-1-pentene with 4-methyl-1-pentene were r 1 = 3 and r 2 = 1 for rac -EB(THI)ZrMe 2 and r 1 = 5 and r 2 = 0.5 for Cp* 2 ZrMe 2 . The polymerization of 1-hexene in the presence of the saturated 1- N, N -diisopropylaminopentane with rac -EB(THI)ZrMe 2 /borate was compared with analogous copolymerizations of 1-hexene/5- N, N -diisopropylamino-1-pentene. The aminopentene was more effective than the aminopentane in inhibiting the rate of total monomer conversion, implicating both intra- and intermolecular mechanisms for inhibition by the amine. Copolymers of 4-methyl-1-pentene/5- N, N -diisopropylamino-1-pentene produced with rac -ethylenebisindenyl zirconium(IV) dimethyl ( rac -EBIZrMe 2 )/borate have higher decomposition temperatures with increasing amounts of aminopentene. This copolymer can be protonated with HCl to yield a methanol-soluble material.