Isoprene Polymerization by Catalyst Systems of Rhodium Complex and Allyl Alcohol

Abstract

Abstract To prepare polyisoprene of controlled microstructure and molecular weight in emulsion systems, a series of polymerizations was carried out with catalyst systems of rhodium complexes and allyl alcohol, with variation of the type of rhodium salts, emulsifiers, and other conditions. A dramatic change in the structure of polyisoprene and also an increase of the polymer yield were brought about by the addition of sodium dodecyl sulfate and allyl alcohol, p-Toluene sulfonic acid and other strong acids exhibited an effect similar to that of the sulfate type emulsifiers on the isoprene polymerization. The degree of polymerization of polyisoprene was increased from 150 to 2000 when the amount of allyl alcohol in the system was decreased from 100 mole % to less than 10 mole % with respect to isoprene monomer. Most samples of polyisoprene prepared with above catalyst systems were found to have almost equi-binary 1,4-cis- and trans- enchainments. The effects of several phosphines and phosphites as additives on the microstructure of polyisoprene prepared with the rhodium complex systems were also examined.