Nanomaterials, conducting polymer

J. Jang, Conducting polymer nanomaterials and their applications, Adv. Polym. Sci., 199,189-260 (2006). 

Another area of intense interest in conducting-polymer nanomaterials for chemical sensing is their combination with carbon nanostructures, most particularly carbon nanotubes, either single-walled (SWNT) or multiwaUed (MWNT). This again reflects the desire to combine the beneficial properties of both types of material to create new combinations with novel properties. CNTs empart high conductivity and high aspect ratios, which yield low percolation thresholds with nanodimensional stmctural order. This has led to their application as chemical sensors. However, CNT-based devices are difficult to fabricate, an issue which may be overcome by their dispersion in a conductive polymeric matrix. 

Jang, J. Conducting Polymer Nanomaterials and Their Applications. Vol. 199, pp. 189-260. 

H. Yoon, Current Trends in Sensors Based on Conducting Polymer Nanomaterials. Nanomaterials 2013,3,524-549. 

Keywords Conducting polymer Nanomaterial Polyaniline Polypyrrole... 

Next section covers extensive discussions of various fabrication methods for conducting polymer nanomaterials in detail. This section is divided by the soft template method, hard template method, and template-free method. 

Based on conducting polymer nanomaterials, various apphcations are reviewed in the final section. These applications include chemical sensor and biosensor, transistor and switch, data storage, supercapacitor, photovoltaic cell, electro chromic device, field emission display, actuator, optically transparent conducting material, surface protection, and substituent for carbon nanomaterials (Fig. 1). Because large amounts of research have been dedicated to this field, it is very difficult to cover whole apphcation fields of conducting polymers. Some comprehensive review articles related to applications of conducting polymers are available [67-73]. 

In general, template method is classified by soft and hard templates. Whereas anodic aluminum oxide (AAO) membrane, track-etched polycarbonate (PC) and zeolite can be used as hard templates, soft templates include surfactant, cyclodextrin, liquid crystal, etc. Compared with soft and hard templates, template-free method represents the fabrication technique of conducting polymer nanomaterials without the template, which is discussed in this section [115]. 

However, it is difficult to control the micelle formation during microemulsion polymerization, hi general, polymerization process is kinetically and thermodynamically unstable because of Ostwald ripening, the growth by collision between monomer droplets and monomer consumption during polymerization [154,155]. It is noteworthy that precise control of the micelle is essential to produce monodisperse and nano-sized conducting polymer nanomaterials. 

Hard template method has been used for the 1-D nanostructures such as nanotubes, nanorods and nanofibers of conducting polymers. The commonly used templates are AAO membrane, and track-etched PC membrane, whose pore size ranges from 10 nm to 100 pm. Hard template methods for synthesizing conducting polymer nanomaterials have been extensively reviewed in recent years [156-160]. 

Template-free techniques have been extensively studied for the fabrication of conducting polymer nanomaterials fabrication. Compared with hard and soft template methods, these methodologies provide a facile and practical route to produce pure, uniform, and high quality nanofibers. Template-free methods encompass various methods such as electrochemical synthesis, chemical polymerization, aqueous/organic interfacial polymerization, radi-olytic synthesis, and dispersion polymerization. 

Tremendous research works have been performed on the synthesis of conducting polymer nanomaterials using dispersion polymerization method [181-188]. There are two categories of dispersion polymerization in order to fabricate the conducting polymer colloids. The first approach forms polymer stabilizer coated conducting polymer nanoparticles. In this case, the monomer and oxidant are dissolved in a stabilized liquid mediiun and the formation of insoluble conducting polymer nanoparticles occurs as the polymerization proceeds. 

Thermal evaporation of PANI has been also developed to fabricate PANI thin film by vacuum deposition of PANI powder on the reference electrode [310]. The chemically synthesized PANI powder was formed in pellet type and the pelletized PANI was evaporated on glass substrates at a pressure of 10 mm Hg to form PANI thin film. The pre-cleaned glass substrate was covered uniformly with PANI thin film and this thin film was utihzed as a carbon monoxide sensor. Thus, thermal evaporation method could be used for thin film formation of conducting polymer nanomaterials [311-313]. 

Owing to the recent push toward conducting polymer nanomaterials, the creative design and development of new PT nanomaterials have provided... 

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