Morphologies and optical properties of poly(2,5-diethoxyphenylene) nanofibril arrays

An anodic aluminum oxide (AAO) membrane can be used as a template for the synthesis of nanostructures. In this paper, we have fabricated poly(2,5-diethoxyphenylene) (EtO-PPP) nanofibril arrays by oxidative coupling polymerization of 1,4-diethoxybenzene (DEB) within the pores of an AAO template. The detailed molecular structure of the polymer nanofibrils was characterized by using the infrared spectrum and the ¹H-NMR spectrum. We have used transmission electron microscopy, scanning electron microscopy, and atomic force microscopy to confirm the morphologies and images of the template and the fabricated nanometer scale of poly(2,5-diethoxyphenylene)nanofibril arrays. The experimental results demonstrate that the pores of the AAO membrane are regular and uniform, and parallel to each other. Furthermore, the EtO-PPP chains in the narrowest template-synthesized fibrils were oriented parallel to the pore axes of the AAO membrane, and perpendicular to the surface of the aluminum substrate. The polymer chain orientation is partially responsible for the enhanced conductivity. The ultraviolet absorption maximum shows that the polymer contains a better extended π-conjugation system along the poly(p-phenylene) backbone, which results in a longer-wavelength shift of the absorption band. The photoluminescence (PL) spectrum of nanofibril arrays exhibits a 5-nm blue shift of the emission in comparison with the unordered molecules. Received: 3 January 2002 / Accepted: 7 January 2002 / Published online: 17 December 2002 RID="*" ID="*"Corresponding author. Fax: +86-931/891-1100, E-mail: lihl@lzu.edu.cn