Diethylaluminum chloride-co-initiated cationic polymerization of isoprene: dramatic effect of the nature of alkyl halide on the properties of synthesized polymers

The cationic polymerization of isoprene using alkyl halide/Et2AlCl initiating system (alkyl halide: tert-butyl chloride, tert-butyl bromide, 2-chloro-2-methylbutane and isopropyl chloride) at different temperatures has been studied. It was shown for the first time that using of tertiary alkyl halide in conjunction with Et2AlCl allowed to synthesize fully soluble solid thermoplastic polymers with reduced unsaturation (41-48 mol%) as well as relatively high glass transition temperature (52-60?) and softening point (102-128?). The substitution of tertiary alkyl halides on the secondary one (isopropyl chloride) results in the obtaining of cross-linked polymers due to the low activity of isopropyl chloride in chain transfer to alkyl halide. It was found that alkyl halide nature, the ratio of alkyl halide to Et2AlCl, duration and temperature of the polymerization of isoprene have dramatic effect on the unsaturation of synthesized polymers as well as their molecular weight, polydispersity, physical and chemical properties.