CNT/PANI composites

However, the storage capability from the fiber electrode based on bare carbon nanomaterial is poor owing to the double-layer capacitance mechanism. Therefore, pseudocapac-itive materials, such as metallic oxide and conducting polymer can also be incorporated into the CNT fiber to enhance the capacitance. For example, CNT/PANI composite fibers... 

In recent decades, there have been many attempts to fabricate CNT/PANI composites [329-337]. The incorporation of nanotubes into PANI can result in novel composite materials with enhanced electrical, electrochemical, and mechanical properties. Eor example, Yu et al. prepared MWCNT/PANI nanocomposites through in situ inverse microemulsion synthesis [334]. Such nanocomposites are characterized by very strong interaction between MWCNTs and conducting polymers. Moreover, MWCNT/PANI core-shell nanowires exhibited better thermal stability and electrical conductivity than the pure PANI. The electrical conductivity of MWCNT/PANI composite containing 1 wt% of MWCNTs increased by one order of magnitude (pure PANI 0.02Scm MWCNT/PANI composite 0.20Scm-i) [334]. 

Due to the outstanding electrical and electrochemical properties of CNT/PANI, composite materials have also been applied as anode for a microbial fuel cell [335], high performance supercapacitors [333,336,337], and as modified electrode for the reduction of nitrite [331]. 

Fan s group at Tsinghua University described a novel method to prepare interesting paper-like CNT/PANI composites by using the CNT network as the template. Compared to the conventional brittle CNT/PANI composites, these paper-Mke composites were much thin and flexible (Figure 38). This work demonstrates a new approach, which... 

HGURE 4.4 Electrical properties of polymer composites. (A) The electrical conductivity of the PS/graphene composite as a function of graphene volume fraction. (B) The electrical conductivity of directly mixing (DM) CNT/PANI and CNT/ PANI nanofibers with different CNT contents in the directions being parallel and perpendicular to the fiber axis. 

Figure 10.17 Potentiodynamic curves acquired in 3.5% NaCl relative to EP PANI (crosses), EP PANI-CNT nanocomposite composite (circles) and EP PANI on EPD CNTs...

Figure 13.5 TEM images of oxidized CNTs (3a) and composite CNT/PANI (3b). Reprinted with permission from Polymer Bulletin, 53,127.138 (2005). Copyright 2005, Springer-Verlag [62].

CNTs are also widely used in actuators [168-171], The addition of CNTs to PANI fibers increased the electromechanical actuation because the CNTs improved the mechanical, electronic and electrochemical properties of the PANI fibers [172-174], Composites based on CNTs are studied for a variety of sensor applications [175-177], For example, polypyrrole or PANI deposited on single-walled CNT networks that can be used as solid state pH sensors [178], A DNA sensor was created fi om a composite of polypyrrole and CNTs fimctionalized with carboxylic groups to covalently immobilize DNA onto CNTs [179], In general, the presence of CNTs tends to increase the overall and selectivity of biosensors, The thermal transport properties of polymer composites can be improved with the addition of CNTs due to the excellent thermal conductivity of CNTs, Such composite are quite attractive for usages as printed circuit boards, connectors, thermal interface materials, heat sinks, lids, housings, etc, [92,180],... 

Regarding the second route mentioned, the colloidal CNT-polymer particle system can be obtained by in situ polymerization. Barraza et al. demonstrated the possibility of preparing SWCNT-filled thermoplastic PS and elastomeric styrene-isoprene copolymer by using a modified version of mini-emulsion polymerization with a cationic surfactant, whereas Deng et al. synthesized CNT/ polyaniline [PANI) composites by in situ emulsion polymerization. Alternatively, the colloidal system can be prepared by direct mixing of the CNTs and the polymer host particles, after the polymerization has already been carried out. 

Structure used for cathode is polymer-carbon such as PANI-CNTs. These composites show a high discharge capacity ( 139mAh/g) as well as a good cyclability in lithirun metal-polymer cells with ionic liquid electrolyte [98]. 

Sivakkumar and coworker have investigated that electrochemical behavior (especially conducting behavior) CNT/PANI nanocomposites-based cell much better than of that pure polyaniline nanofiber-based cell [46-48]. It is ultimate because of very efifective electric double-layer capacitance in the CNT-based electrode. During the study, it has been found that the current passed by the PANl/CNT composite-based device is higher than that of pure PANI nanofiber, which means that the capacitance of the nanocomposites is larger than that of flie pure PANI nanofiber. This indicates a synergistic effect from the combined contributions from PANI and CNT [46] (Fig. 6). 

Fig. 23 a, b are digital macrographs of the flexible Buckypaper/PANi composite and the brittle CNT/PANi tablet, respectively (Reproduced with permission from [91])... 

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