Conjugated Polymer Network Films from Precursor Polymers:  Electrocopolymerization of a Binary Electroactive Monomer Composition

Abstract

We report the synthesis and electropolymerization of a precursor polymer with a binary molecular composition of thiophene and carbazole electroactive groups to form ultrathin films of conjugated polymer networks (CPN) on flat indium tin oxide (ITO) substrates. In the past we have demonstrated the precursor polymer approach based on a single pendant electroactive group. In this work, we describe the interesting electrocopolymerization mechanism and properties of precursor polymers prepared with two different types of pendant electroactive groups (statistical copolymer) and compared behavior to their respective homopolymers. The presence of a smaller amount of carbazole induces the electropolymerization of the higher oxidation potential thiophene units via the reaction of a radical cation and a neutral molecule pathway. These electrochemically generated thin films gave unique optical, electrochemical, and morphological properties as a function of composition. The film properties were investigated by cyclic voltammetry (CV), spectroelectrochemistry, EQCM, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS).

RAFT “grafting-through” approach to surface-anchored polymers: Electrodeposition of an electroactive methacrylate monomer

“…The peak of the oxidation potential shifted to higher values as the thickness of the film increased. This potential shift is attributed to the heterogeneous electron-transfer kinetics, IR drop of the film (V total = V across film + I(R film + R soln )), and the decrease of the film conductivity [23]. The CV exhibited a re- versible process, with an almost constant current increase after each cycle.…”

“…Electropolymerization of heteroaromatic monomers such as thiophene, pyrrole, aniline, and carbazole to form π-conjugated or conducting polymers has been well documented [19][20][21][22] The study of such electropolymerizable monomers is interesting, as it can yield unique polymerization mechanisms and electro-optical applications including electrochromic properties [23]. In our group, carbazolecontaining polymers and dendrimers have been synthesized and studied [24][25][26][27][28] because of their potential applications on electroluminescent devices [29][30][31], photorefractive materials [32,33], electrochromic materials [34,35], and memory devices [36].…”

“…In our group, carbazolecontaining polymers and dendrimers have been synthesized and studied [24][25][26][27][28] because of their potential applications on electroluminescent devices [29][30][31], photorefractive materials [32,33], electrochromic materials [34,35], and memory devices [36]. In all the above applications, the main use of carbazole-derivatized polymers for electro-optical function involves efficient hole transport, good solution processing properties, and high chemical stability [37][38][39][40].…”

“…In all the above applications, the main use of carbazole-derivatized polymers for electro-optical function involves efficient hole transport, good solution processing properties, and high chemical stability [37][38][39][40]. Using the precursor polymer approach, polymers with electroactive side-chain functional groups can form conjugated polymer networks (CPNs) on the electrode surface upon chemical or electrochemical oxidation processes [24][25][26][27][28]37]. The CPN formation [41,42] has also been applied to dendrimeric precursors forming shape-persistent conjugated nano-objects and electrooptically active films [43,44].…”

Electro‐Copolymerization of Layer‐by‐Layer Deposited Polythiophene and Polycarbazole Precursor Ultrathin Films

“…In the past we have demonstrated the precursor polymer approach based on both single and mixed pendant electroactive groups to form uniformly smooth films. [10][11][12][13][14] We hereby report the synthesis and properties of precursor polyelectrolytes with thiophene and carbazole pendant electroactive groups deposited on ITO using the LbL approach and their electrochemical copolymerization and cross-linking behavior. In principle, by using the LbL approach, one can force the two electroactive groups to copolymerize as the degree of cross-linking increases within the layers on the ITO surface.…”