Highly soluble diphenylfluorene‐based cardo copolyimides containing perylene units

Abstract

AbstractTwo series of novel ternary copolyimides containing perylene and fluorene units in the backbone were synthesized by one‐step polycondensation of diamine (4,4′‐(9H‐fluoren‐9‐ylidene)bisphenylamine, FBPA) with perylene dianhydride (3,4,9,10‐perylenetetracarboxylic dianhydride, PTCDA) and a comonomer [4,4′‐(hexafluoroisopropylidene) diphthalic anhydride, 6FDA or 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride, BDTA]. The polymers were named as PFFx (PTCDA‐FBPA‐6FDA) and PFBx (PTCDA‐FBPA‐BTDA), respectively, and their chemical structures were identified by FT‐IR spectra and elemental analyses. Perylene contents in the copolyimides were determined through a quantitative UV‐vis spectroscopy method, which are in agreement with the values calculated from the added raw materials both for PFFx and PFBx. Gel permeation chromatography (GPC) measurement suggested that the weight average molecular weight (Mw) is in the range 2.1–5.09 × 104 and the molecular weight distribution (MWD) is 1.86–2.72 for PFFx, and those for PFBx are 2.64–4.73 × 104 and 2.44–2.92, respectively. Thermogravimetric analysis (TGA) measurements showed that the copolyimides are very thermally stable with a temperature of 10% weight loss (T10) in the range 546–563°C for PFFx, and 538–548°C for PFBx. The copolyimides also have good solubility in common organic solvents such as chloroform and tetrahydrofuran. These unique properties can be attributed to the existence of the bulky diphenylfluorene moieties in the polymer backbone. All the copolyimides can emit strong fluorescence both in solution and in films, which make them possibly be used as thermostable light‐emitting materials for organic light‐emitting diodes. Copyright © 2006 John Wiley & Sons, Ltd.