Abstract
The present study centers on the supramolecular structure of a hairy rod conjugated polymer based on a poly(phenylenevinylene) backbone with oligo (oxyethylene) side chains attached, an alternating copolymer, poly{[2,5-di (2-(2-ethoxy-ethoxy)ethoxy)-1,4- phenylene vinylene]-alt-1,4-[phenylene vinylene]} (DTEO-alt-PV) in the neat state and the blends with other substances, including an oligomeric amiphiphile, a homopolymer and diblock copolymer. Due to the semiconductivity and electroluminescence of this conjugated polymer as well as its ability of ion transports, DTEO-alt-PV has the potential for applications in various fields, including photoelectric device and the ion-transportable separator between the electrodes. Nevertheless, the photophysical properties and the final device performance are expected to be strongly influenced by the structure and morphology of the polymer. In order to reveal the morphology and the structure-properties correlation of DTEO-alt-PV, for facilitating the optimization of optical and electronic properties, we proceed with a systematic study using SAXS, WAXS, TEM, UV, and PL as the major tools to achieve this goal. For the present results, the powder diffraction profile revealed that the crystal structure of DTEO-alt-PV consisted of rod-like PPV segments packed in a monoclinic unit cell with angles β=103o. TEM micrograph revealed a semicrystalline lamellar structure with the interlamellar distance of c.a. 60 nm and a spherulitic morphology, and thus showed that DTEO-alt-PV was a semicrystalline polymer. Moreover, we also found that DTEO-alt-PV formed an orthorhombic mesophase in the shear-oriented film. In order to examine the crystallization behavior of DTEO-alt-PV, isothermal crystallization kinetics was investigated on the basis of the well-known Avrami equation as well. Finally, it was demonstrated that the absorption and emission behaviors were significantly affected by the thermally induced changes in the morphology. The correlation between photophyscial properties and morphology of DTEO-alt-PV had also been showed in the present work. Another task is creating special supramolecular structure of DTEO-alt-PV (and thus possibly improve its physical and photophyscial properties) through the blending with an amiphiphile. The blend of DTEO-alt-PV and a surfactant, 4-n-dodecylresorcinol (DR), formed a lamellar structure which consisted of the parallelly-aligned DTEO-alt-PV layers and interdigitatedly-aligned DR layers.