Synthesis and properties of a novel brush-type copolymers bearing thiophene backbone and 3-(N-carbazolyl)propyl acrylate side chains for light-emitting applications

A new light-emitting and hole transporting copolymer 2,5-Poly(3-[1-ethyl-2-(2-[poly(3-(N-carbazolyl)propyl acrylate)]propionate)]thiophene) (PT-g-PCPA) was prepared via atom transfer radical polymerization (ATRP) of a 3-(N-carbazolyl)propyl acrylate (CPA) monomer, initiated by a macroinitiator with ATRP initiating sites distributed along polythiophene (PT) backbone. The resulting polymers were characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (H-1 and C-13 NMR) spectroscopy and differential scanning calorimetry (DSC). The optical properties of polymers were investigated by UV-vis and fluorescence analyses. The electrochemical properties of polymers were investigated by cyclic voltammetric (CV) measurements. The results confirmed that the introduction of the PCPA side chains trapped the polythiophene backbone in a solution-like conformation, which inhibited the aggregation of polythiophene backbone effectively. Additionally, the energy transfer process from PCPA side chains to the PT backbone in both solution and film states were also evidenced. Electroluminescence devices fabricated from the copolymer demonstrated that copolymer could act as both light emissive and hole-transporting materials.