Pristine SWNT

Modified CNTs feature various spectral changes depending on the methods and the location of modifications. These changes include variations in band frequencies, width, and intensities. For example, aryldiazonium salts [139] were used to modify individual sodium dodecyl sulphate (SDS) coated SWNTs with aryl group. The Raman spectrum of functionalized (SDS-free) SWNTs shows a disorder mode much higher than pristine SWNT the radial breathing modes are nearly unobservable. 

Proper solution electrochemical experiments on pristine SWNTs were only possible after the recent discovery of an innovative way to form thermodynamically stable solutions of unmodified and uncut SWNTs.17,60 Upon reduction with alkali metals, SWNTs produce polyelectrolyte salts (Scheme 9.16) that are soluble in polar organic solvents without the use of sonication, surfactants, or functionalization. Polyelectrolyte SWNT salts were obtained by reacting arc-discharge samples (a-NT) or HiPco samples (h-NT) with different alkali metals (Na, K). 

Fig. 11.9 Raman spectra of (a) pristine SWNTs, (b) SWNTs treated at high pressure and high temperature in the absence of a hydrogen atmosphere, and (c) hydrogenated SWNTs after annealing in vacuum at =550°C for 1 h...

Noncovalent interaction of SWNTs with organic molecules (pyrene and naphthalene) and surfactants of different types in aqueous solutions leads to the spectral shift of lines and its intensity redistribution in spectra in comparison with the spectra of pristine SWNT. 

Figure 14.2. The mechanical properties of 0.5 wt% SWNT/Epoxy composites (a) tensile test of neat epoxy resin (b) tensile test of pristine-SWNT/epoxy ...

Figure 14.3. TEM images of epoxy-grafted SWNTs (a) pristine SWNT and (b) epoxy-grafted SWNT [11].

Figure 14.11. Tensile strength of CNT/Epoxy composites with the 0.5 wt% SWNT loading (a) neat epoxy resin, (b) pristine SWNT/epoxy, (c) cut-SWNT/Epoxy (11).

Chemical functionalization of CNT surfaces could improve their dispersion in the polymer matrix and enhance the nanotube-polymer interfacial interaction and the mechanical load transfer. The effects of nanotube functionalization on the properties of CNT-TPU composites have been investigated in details. Xia and Song have synthesized polycaprolactone polyurethane (PU)-grafted SWNTs (PU-g-SWNTs) and corresponding PU-g-SWNT-PU composites by in-situ polymerization. The results show that PU-g-SWNTs improve the dispersion of SWNTs in the PU matrix and strengthen the interfacial interaction between the PU and SWNTs. Compared with neat PU and pristine SWNT PU composites, PU-g-SWNT-PU composites demonstrate remarkable enhancement on Young s modulus. The Young s modulus of a 0.7 wt /o PU-g-SWNT-PU composite increases by 178% over the blank PU and 88% over the 0.7 wt% pristine SWNT-PU composite, respectively. 

Figure 4.7 Preparation of CE composites with SWNTs functionalised by a method that combines covalent and non-covalent approaches. p-SWNTs -pristine SWNTS O-SWNTs - epoxidized SWNTs. Reproduced with permission from Yuan and Chan-Park. ...

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