Functional olefin copolymers: Uniform architectures of propene/7-methyl-1,6-octadiene copolymers by ATR-FTIR spectroscopy control of monomer composition

Propene and 7-methyl-1,6-octadiene (MOD) were copolymerized with the cataly st system rac-Et[Ind](2)ZrCl2/MAO in semibatch reactions and under constant comonomer concentrations using an autoclave setup that is equipped with an ATR-FTIR sensor coupled with a dosage system for the liquid MOD comonomer. The concentration of the monomer propane is regulated precisely in both ty pes of polymerization by a gas flow controller. This setup enables to monit or the MOD concentration on-line and in real-time during the reaction by fo llowing characteristic bands arising from the double bonds. Copolymers with poorly defined incorporation data and thermal properties were obtained wit hout control of the MOD concentration in time. This is caused by a nonunifo rm distribution of the MOD units over the polymer chains due to a relativel y large shift of the MOD concentration during the copolymerization reaction . By means of solvent extraction fractionation experiments, these copolymer s could be fractionated into three fractions with different amounts of inco rporated MOD, varying from 11.5 to 7.2 mol %. Functional copolymers with un iform architectures (up to 30.5 mol % incorporated MOD) were prepared by us ing the on-line ATR-FTIR data to control the MOD concentration during the c opolymerization reactions.