Kinetic Studies of the Alternating Copolymerization of Butadiene with Acrylonitrile Catalyzed by the Ethylaluminum Dichloride–Vanadyl Chloride System
The mechanism of the alternating copolymerization of butadiene with acrylonitrile catalyzed by EtAlCl<SUB>2</SUB> and VOCl<SUB>3</SUB> was investigated experimentally using various concentrations of catalysts at varying temperatures. A step-growth polymerization was postulated from the characteristic feature of polymerization that the molecular weight of a resultant polymer increases in the course of polymerization. A linear correlation was found to exist between the ratio of the yield to the degree of polymerization and the yield, which suggests that polymerization proceeds with rapid initiation and chain transfer reactions. The overall rate of polymerization was found to be expressed as a function of (EtAlCl<SUB>2</SUB>)<SUP>3⁄2</SUP>×(VOCl<SUB>3</SUB>)<SUP>1⁄2</SUP> and the concentration of the active species as a function of (EtAlC<SUB>2</SUB>)<SUP>1⁄2</SUP>×(VOCl<SUB>3</SUB>)<SUP>1⁄2</SUP>. These facts suggest that the active species is generated from the dissociation of the EtAlCl<SUB>2</SUB>–VOCl<SUB>3</SUB> complex through a redox mechanism and the propagation reaction takes place between the polymer radical and a complexed monomer of butadiene–acrylonitrile–EtAlCl<SUB>2</SUB>. Vanadium compound acts not only as a generator of the active species but also as a useful cocatalyst capable of regenerating the complexing agent for the monomer and preventing the polymer from gel formation.
- Polymer Journal
Polymer Journal 1(2), 155-163, 1969
The Society of Polymer Science, Japan