Carboxylic functionalized SWCNTs

An amount of 1.20 mg (0.9 mmol) of pentyl carboxylate-functionalized SWCNTs (Scheme 1.23) was mixed with 150 mg (0.9 mmol) of 4,5-benzo-l,2-oxathiin-2-oxide in 40 mL of ODCB and the mixture was irradiated in a focused microwave reactor at 150 W for 45 min. The ODCB was removed by vacuum distillation and the residue was purified by washing several times with pentane and diethyl ether to obtain benzobutenylene-functionalized SWCNT as a dark-brown solid [171]. 

Carboxyl-functionalized SWCNT/PANI In-situ chemical polymerization Drop coating HCI and NH3 [52]... 

In the thermal studies conducted by Song et al. (76), the Tg increased modestly with the addition of pure and carboxylic-functionalized MWCNTs in PLA matrix. Also, the T and Tm of the nanocomposites were found to be lower than pure PLLA. Tsuji et al. (63) also observed the same trend of decreasing T in the nanocomposites compared with pure PLA however, here the nano-fillers are SWCNTs. In addition, several studies reported the Tg of the nanocomposites was lower than that of pure PLLA (61, 63,65). 

Another H2/O2 biofuel cell based on a hyperthermophihc 02-tolerant hydrogenase and bilirubin oxidase was reported by Lojou and coworkers [41]. Both electrodes were based on SWCNTs bearing carboxylic functions on which the enzymes were covalently finked. The electrodes were plunged into separate electrolyte baths separated by a membrane and fueled by pure H2 and O2. The biofuel cell delivers power densities up to 0.3mW/cm at 0.6 V with an open-circuit voltage of 1.1 V, with 24 h stability under continuous operation. 

Marques et al. [49] used hydrothermal oxidation in HNO3 at elevated pressure (0.5 MPa) and temperature (120-200°C) to functionalize SWCNTs and to control both the type and amount of surface functional groups. Their results showed that the degree of surface functionalization is correlated with the HNO3 concentration by a first-order exponential function. Lebron-Colon et al. [53] used dye-assisted photo-oxidation to functionalize SWCNTs. Their stndy revealed that photo-oxidized SWCNT contain np to 40% more oxygen (11.3 at.%) bound to the tnbe snrface (chemisorption), as compared to H2S04-treated samples (6.7 at.%), primarily in the form of carboxylic, carboxylate, and ester groups. 

Mugadza et al. [58] described the synthesis of conjugates based on carboxylic acid functionalized SWCNTs and 2,(3)-tetra-(4-oxo-benzamide)phthalocyaninato cobalt(II) (CoTOBPc) applied in the detection of amitrole (herbicide). The chemical bonding (imides linkages) that are formed between the CoTOBPc and SWCNTs are... 

Almost at the same time Nyokong et al. [125] used a similar method to covalently bind Ni(II)-2 to carboxylic acid functionalized SWCNT. More recently, Nyokong et al. [126] have reported a method of functionalization of SWCNTs, with amine groups using a previously developed diazonium approach. This makes it possible the direct attachment of the Zn(II)-10 by an amide bond to the CNT as illustrated in Fig. 4. Kim and Jeon [129] have reported on the immobilization of a cobalt porphyrin (cobalt tetrakis(o-aminophenyl)porphyrin) of several carbon nanomaterials via the diazonum strategy, but in this case, the diazotation was performed on the macrocycle, by the diazotation of aromatic amine groups of the porphyrin. 

Carboxylic functionalized single-walled carbon nanotubes (SWCNTs) Carbon nanotubes if appropriately functionalized can provide desired microenvironment condncive to neurogenesis (Sridharan et al., 2009). Tay et al. (2010) from Nanyang Technological University,... 

Newkome-type dendrons were attached to the carbon scaffold of SWCNTs and MWCNTs by defect group functionalization [108], First- and second-generation amine dendrons such as those depicted in Fig. 1.5 were condensed with the carboxyl groups of purified and opened SWCNTs and MWCNTs according to the car-bodiimide technique [108], These CNTderivatives can be expected to combine the characteristics of carbon nanotubes with those of dendrimers, potential building blocks for supramolecular, self-assembling and interphase systems. 

HiPCO-SWCNTs were oxidized in a UV-03 gas-solid interface reaction and subsequently assembled on a rigid oligo(phenylenethynylene) self-assembled monolayer (SAM). In a chemical assembly , based on condensation between the carboxylic acid functionalities of the 03-oxidized SWNTs and the amine functionalities of the SAMs, SWCNT-amides were formed in ordered arrays [116]. 

Carboxylic groups positioned at the open ends of SWCNTs were coupled to amines to form AFM probes with basic or hydrophobic functionalities by Wong et al. [117] (Scheme 1.8). Force titrations recorded between the ends of the SWCNT-AFM tips and hydroxy-terminated SAMs confirmed the chemical sensitivity and robustness of the AFM tips. Images recorded on patterned SAM allowed real molecular-resolution imaging [117]. 

Functionalization of SWCNTs and MWCNTs was shown to alter significantly the ability of these materials to induce oxidative stress. The addition of polyethylene glycol (PEG), sulfur (SH), or amine (NH2) groups reduced the biological oxidative damage, while it was slightly increased in the presence of carboxylic or hydroxide functionalization [14]. 

As has been pointed out by Cantalini et al. (2003), the cross-sensitivity of SWCNT gas sensors can lead to false alarms in a complex atmosphere. To exploit CNT-based devices, it is crucial to find ways to give them selectivity. To modify the chemical activity of SWCNTs and enhance their sensitivity to a specific gas, the common approach is to functionalise the nanotube side-wall. There are two types of functionalisation depending on the binding of the functional group onto the nanotube sidewall covalent functionafisation and non-covalent functionalisation. Covalent functionalisation of SWCNTs is often obtained from the esterification of carboxylic add groups formed on... 

Recently, Gao and co-workers " developed a facile approach to the functionalization of MWCNTs and SWCNTs via nitrene chemistry, and functional groups such as hydroxyl, carboxyl and amino could be immobilized... 

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