Synthesis of Block Copolymers of Ethylene with Styrene and n-Butyl Acrylate via a Tandem Strategy Combining Ethylene “Living” Polymerization Catalyzed by a Functionalized Pd−Diimine Catalyst with Atom Transfer Radical Polymerization

Abstract

We report a new two-step tandem strategy combining two versatile “living” polymerization techniques, Pd−diimine catalyzed ethylene “living” polymerization and atom transfer radical polymerization (ATRP), for the synthesis of functionalized polyethylene (PE) diblock copolymers containing an ethylene block and a functional monomer block, such as styrene and n-butyl acrylate. The key to the success of this tandem strategy is the development of a novel functionalized Pd−diimine catalyst, [(ArNC(Me)−(Me)CNAr)Pd(CH2)3C(O)O(CH2)2OC(O)C(CH3)2Br]+SbF6- (Ar = 2,6-(iPr)2C6H3) (3), which uniquely contains a 2-bromoisobutyryl substituting group on its chelate structure. This catalyst was synthesized by convenient equimolar reaction of the acetonitrile Pd−diimine adduct, [(ArNC(Me)−(Me)CNAr)Pd(CH3)(N⋮CMe)]+SbF6- (Ar = 2,6-(iPr)2C6H3) (1), with a functional acrylate monomer, 2-(2-bromoisobutyryloxy) ethyl acrylate (BIEA). The remarkable feature of 3 lies in its unprecedented ability to catalyze ethylene “living” polymer...