Synthesis of grafted poly(p-phenyleneethynylene) with energy donor-acceptor architecture via atom transfer radical polymerization:: Towards nonaggregating and hole-facilitating light-emitting material

In this contribution, we demonstrate a new effective methodology for constructing highly efficient and durable poly(p-phenyleneethynylene) (PPE) containing emissive material with nonaggregating and hole-facilitating properties through the introduction of hole-transporting blocks into the PPE system as the grafting coils as well as building the energy donor-acceptor architecture between the grafting coils and the PPE backbone. Poly(2-(carbazol-9-yl)ethyl methacrylate) (PCzEMA), herein, is chosen as the hole-transporting blocks, and incorporated into the PPE system as the grafting coils via atom transfer radical polymerization. The chemical structure of the resultant copolymer, PPE-g-PCzEMA, was characterized by NMR and gel permeation chromatography, showing that the desirable copolymer was obtained with the narrow polydispersity. The increased thermal stability of PPE-g-PCzEMA was confirmed by thermogravimetric analysis and differential scanning calorimetry along with its macroinitiator. The optoelectronic properties of this copolymer were studied in detail by ultraviolet-visible absorption, photoluminescence emission and excitation spectra, and cyclic voltammogram (CV). The results indicate that PPE-g-PCzEMA exhibits the solid-state luminescent property dominated by individual lumophores, and also the energy transfer process from the PCzEMA blocks to the PPE backbone with a relatively higher energy transfer efficiency in the solid-state compared to that of the solution state. Additionally, the hole-injection property is greatly facilitated due to the presence of PCzEMA, as confirmed by CV profiles. All these data indicate that PPEg-PCzEMA is a good candidate for use in optoelectronic devices. (c) 2007 Wiley Periodicals, Inc.