Copolymerization of Styrene and 2-Methyl-5-Vinyl Pyridine by Al(C₂H₅)₃-TiCl₄ Catalyst System

Abstract

Copolymerization of styrene with 2-methyl-5-vinyl pyridine was carried out by Al (C₂H₅)₈-TiC1₄, catalyst system at the Al/Ti mole ratio of 2.5: 1 and at 70°C. In order to compare with this catalyst system, copolymerization by azo-bis-isobutyronitrile initiator and Na catalyst was also carried out. The monomer reactivity ratios were obtained as follows:γ_st (±0.1), γ_mvp=2.9 (±0.3), γ_stγ_mvp=1.45 (ALEt₃-TiCl₄),
γ_st=0.60 (±0.1), γ_mvp=0.68 (±0.1), γst_mvp=0.41 (AZN)
γ_st=0.3 (±0.1), γ_mvp=2.9 (±0.3), γst_mvp=0.87 (Na)
These results indicate that the copolymerization by Al (C₂H₅) ₃-TiCl₄ is anionic. Solubility in methyl ethyl ketone, infrared absorption spectrum and X-ray diffraction pattern were measured on this copolymer. From these experimental results, it may be concluded that the isotactic regular sequence of 30-40 styrene units is necessary in order that this copolymer exhibits the characteristic properties of isotactic polystyrene.