Well-defined triblock copolymers of polyethylene with polycaprolactone or polystyrene using a novel difunctional polyhomologation initiator

Abstract

α,ω-Dihydroxy polyethylene, valuable precursor for the synthesis of polyethylene-based terpolymers with polar blocks, was synthesized by polyhomologation of dimethylsulfoxonium methylide with 9-thexyl-9-BBN, a novel difunctional initiator with two active and one blocked sites.

Abstract

α,ω-Dihydroxy polyethylene was synthesized by polyhomologation of dimethylsulfoxonium methylide with 9-thexyl-9-BBN (9-BNN: 9-borabicyclo[3.3.1]nonane), a novel difunctional initiator produced from 9-BBN and 2,3-dimethylbut-2-ene, with two active and one blocked sites, followed by hydrolysis/oxidation. The terminal hydroxy groups were either used directly as initiators, in the presence of 1- tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ ⁵,4λ ⁵-catenadi(phosphazene) ( t-BuP2), for the ring opening polymerization of ε-caprolactone to afford polycaprolactone- b-polyethylene- b-polycaprolactone (PCL- b-PE- b-PCL) or after transformation to atom transfer radical polymerization initiating sites, for the polymerization of styrene to produce polystyrene- b-polyethylene- b-polystyrene (PSt- b-PE- b-PSt) triblock copolymers. Molecular characterization by ¹¹B, ¹³C and ¹H NMR as well as FTIR, and high temperature GPC (HT-GPC) confirmed the well-defined nature of the synthesized new difunctional initiator and triblock copolymers. Differential scanning calorimetry was used to determine the melting points of PE and PCL.