Synthesis and properties of polyethylene with side-chain triphenylamines as hole-transporting materials

Abstract

The copolymerization of ethylene with triphenylamine (TPA)-containing a-olefin monomer 1 using a rac-Et(Ind)(2)ZrCl2 (EBIZr)/MAO catalytic system was investigated to prepare polyethylene with pendent TPA groups. Despite the presence of a large excess of TPA moieties, the polymerization reactions efficiently produce copolymers of high-molecular-weight with the comonomer incorporation up to 6.1 mol % upon varying the comonomer concentration in the feed. Inspection of the aliphatic region of the C-13-NMR spectrum and the estimated copolymerization parameters (r(1) approximate to 0 for 1 and r(E) approximate to 43 for ethylene) reveal the presence of isolated comonomer units in the polymer chain. While UV-vis absorption measurements of the copolymers show an invariant absorption feature, PL spectra exhibit a slightly red-shifted emission with increasing content of 1 in the polymer chain. All the copolymers show high thermal stability (T-d5 > 436 degrees C), and the electrochemical stability toward oxidation is also observed. Particularly, the copolymer displays hole-transporting ability for the stable green emission of Alq(3) when incorporated into the hole-transporting layer of an electroluminescence device. (c) 2008 Wiley Periodicals, Inc.