Electrochemically Generated Conjugated Microporous Polymer Network Thin Films for Chemical Sensor Applications

Abstract

various chemicals with high sensitivity and shorter response times if compared to small molecules, linear polymer analogues, and other porous materials. [14] In most cases, CMPNs synthesized chemically via metal catalyzed C-C coupling reaction are insoluble, unprocessable powder solids, and pose difficulties to fabricate portable sensor devices. [1] In this regard, CMPN materials in the form of thin films are appropriate for the construction of portable detection devices and they also find applications in organic electronics and photovoltaics.Electrochemical oxidative polymerization technique is a promising approach to grow high-quality CMPN thin films with controlled thickness and surface roughness suitable for device fabrication. [15] It requires shorter times, easy purification process as it does not involve any metalcatalyst; hence the films are of high chemical purity and the films can be coated on various substrates including flexible electrodes. Electropolymerization is carried out in a cell connected to potentiostat and containing monomer solution with a supporting electrolyte, three electrodes viz. working electrode (WE) where the polymerization occurs, counter electrode (CE), and a reference electrode (RE). Electrochemical process of CMPN thin film preparation is understood in a similar way as electrochemical synthesis of linear conducting polymers described by Nelson, Lapkowski, and Ludwigs. [16] During the last few decades, studies on conducting polymers provided detailed understanding of polymerization process and effect of essential parameters such as applied potential, overoxidation, supporting electrolyte, temperature, and solvents on polymer growth and its properties. [16] All these studies were concentrated on electrochemical oxidation of bisubstituted monomers having carbazole, thiophene, or pyrrole functional groups to corresponding linear polymers for electrochromic devices, optoelectronics, and sensors applications. [17] Similar electrochemical principles were adopted for the fabrication of CMPN thin films using various multicarbazolyl or thienyl monomers having different aromatic cores for applications like organic solar cells, organic light emitting diodes, supercapacitors, and chemical sensors. [15] The scope of this short trend article is limited to CMPN films generated from carbazolyl-or thienyl-based monomers by electrochemical oxidative polymerization for electrochemical or optical-sensing applications. In the first part, preparation of CMPNs via electrochemical approach from multicarbazolyl-/ thienyl monomers containing different aromatic cores, their CMP Thin Film SensorsElectrogenerated π-conjugated microporous polymer network (CMPN) thin films are potential materials for highly sensitive detection of harmful chemical species as they show fast response, high signal amplification, and easy fabrication of devices. In the last few years, several CMPN thin films from carbazolyl and thienyl monomer building blocks having a variety of aromatic cores have been reported for different...

Electropolymerization of robust conjugated microporous polymer membranes for rapid solvent transport and narrow molecular sieving

“…In the cathodic sweep scan, the dimeric carbazole cations were reduced to their neutral state, resulting in a reduction peak at 0.60 V. In the second and further scan cycles, both the oxidation and reduction peak currents increased with the number of cycles owing to the extension of polymerization and the membrane growth. Eventually, a highly crosslinked film was formed on the support 16 . Figure 2d shows the membrane thickness vs. the number of growth cycles.…”

Thin Functional Polymer Films by Electropolymerization

“…However, the formed conjugated polymer chains are usually twisted and entangled, leading to a disordered solid-state structure that might result in lower performance in applications where high order is required (e.g., organic electronics). On this ground, over the past years, electrochemical generation of polymer films has been intensively studied, starting from multifunctional monomers (with three or more linkable sites) [19,20,21,22,23]. This methodology usually leads to the formation of films with a 3D network structure that not only maintains all advantages of 1D polymer films but also shows a more robust electronic structure, often accompanied by the occurrence of inherent microporosity with high surface area values [24,25,26].…”

The efficient preparation of carbazole‐based conjugated porous polymer films using electrochemical method and their fluorescence property study

“…Relatively, another effective method for preparing CPPs films is the electropolymerization, which is cost-efficient and labor-saving. [19][20][21][22] And polymers films polymerized using this method also have good porosity and large specific surface area. Also, for electrochemical methods, different preparation conditions will result in different properties of CPPs.…”

“…In fact, the reprocessing is difficult, and some properties of these polymers are still undetermined. Relatively, another effective method for preparing CPPs films is the electropolymerization, which is cost‐efficient and labor‐saving 19‐22 . And polymers films polymerized using this method also have good porosity and large specific surface area.…”