Non-covalent functionalisation

Non-covalent functionalised carbon nanotubes as highly specific electronic biosensors... 

Although SWCNTs show attractive features, the development of selective gas sensors based on SWCNTs remains a great challenge. Several methods exposed in Section 10.4 have been explored to overcome this problem. The most mature routes to reach gas selectivity are focused on the chemical covalent or non-covalent functionalisation of SWCNTs, the decoration of SWCNTs with metallic nanoparticles and the diversification of the metallic electrodes. 

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... 

The non-covalent functionalisation of nanotubes normally involves van der Waals, 71-71, CH-ti or electrostatic interactions between polymer molecules and the CNT surface. 

The advantage of non-covalent functionalisation is that it does not alter the structure of the nanotubes and therefore both the initial electrical and mechanical properties should also remain unchanged. However, the efficiency of the load transfer might decrease as the forces between the wrapping molecules and the nanotube surface may be relatively weak. 

Figure 4.2 Synthesis of the compatibilizer (P2) and schematic illustration of non-covalent functionalisation of MWNTs by P2. Reproduced with permission from Mandal and Nandi." EBIBT- 3-[l-ethyl-2(2-bromoisobutyrate)] thiophene DMAEMA- 2-(dimethylamino ethyl methacrylate) HMTETA- 1,1,4,7,10,10-hexamethyltriethylenetetra-mine ATRP- atom transfer radical polymerization.

Martinez and co-workers reported an interesting approach which is based on non-covalent functionalisation of SWNTs with amphiphihc block copolymers (BCs) containing polyethylenoxide (Figure 4.3). They have shown... 

Non-covalent functionalisation approaches also enable the preparation of polymer composites with significantly improved mechanical properties. For example, in the recent work of Yuan et al three different polymers such as polyimide without side-chain (PI), polyimide-graft-glyceryl 4-nonylphenyl... 

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