Polyfluorene Derivatives with Hydroxyl and Carboxyl Substitution: Electrosynthesis and Characterization

Abstract

Novel high-quality poly(9-hydroxyfluorene) (PHF), poly(9-fluorenecarboxylic acid) (PFCA), and poly(9-hydroxyl-9-fluorenecarboxylic acid) (PHFCA) films can be easily electrodeposited by low-potential anodic oxidation of fluorene derivatives, which contain either the electron-withdrawing carboxyl group (-COOH) or the electron-donating hydroxyl group (-OH), using a midstrength Lewis acid boron trifluoride diethyl etherate (BFEE) as the solvent and supporting electrolyte. The complexing reaction between the -COOH or -OH groups at the C(9) position of these fluorene derivatives and BFEE increased the ionic conductivity of the BFEE system as an electrolyte significantly. The 13C NMR spectra clearly demonstrates that the chemical shift of carbons at the C(9) and C(14) positions has made a low-field shift. This change in the chemical shift of the carbon atoms confirms the formation of complexion cations when FCA or HFCA was mixed with BFEE. The as-formed polymer films showed good redox behavior and thermal stabil...