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Über dieses Buch

In this thesis, Claudia Backes guides the reader through her multidisciplinary research into the non-covalent functionalization of carbon nanotubes in water. Although one of the most remarkable materials of the 21st century, carbon nanotubes often have limited application because of their intrinsically low solubility and polydispersity. The author shows that rational surfactant design is a powerful tool for chemists because it can unmask the key to solubilization and allow us to tailor nanotube surface and optical properties in a fully reversible fashion. Aspects of organic, physical and analytical chemistry, as well as colloidal sciences are covered in this outstanding work which brings us one step closer to exploiting this super-material to its full potential.



Chapter 1. Introduction

Carbon nanotubes (CNTs) belong to the family of synthetic carbon allotropes and are characterized by a network of sp2 hybridized carbon atoms. The one dimensional (1D) carbon nanotubes can thus be queued between their zero dimensional relatives fullerenes and the two dimensional (2D) relative graphene. The structure of nanotubes has first been described as helical microtubules of graphitic carbon in 1991 by Iijima who generated the novel material by an arc discharge evaporation process originally designed for the production of fullerenes. Since then, extensive research has shed light into the structure and properties of this highly remarkable carbon allotrope.
Claudia Backes

Chapter 2. Proposal

Despite their unique physical, mechanical and electronic properties single-walled carbon nanotube-based technology has commenced slowly. This can be traced back to two major hurdles namely their poor solubility in common solvents on the one hand and the polydispersity of the as-produced material with regard to diameter, length and chirality on the other hand. SWCNT solubilization can conveniently be achieved by the aid of surfactants noncovalently anchored to the SWCNT surface. The resulting dispersion can be subjected to sorting scenarios recently developed. However, up to now, separation efficiencies and yields are poor as sorting is restricted to individualized SWCNTs. Individualization rates by common surfactants are below 25% (after mild centrifugation) so that novel SWCNT surfactants with superior properties are sought for.
Claudia Backes

Chapter 3. Results and Discussion

In the first section, the suitability of seven different perylene bisimide derivatives (17) with respect to nanotube dispersion and exfoliation in water has been investigated (Scheme 3.1) [1, 2]. The syntheses of these systems is described in the literature [2, 3]. As outlined by numerous studies [412], the inclusion of polycyclic aromatic units in nanotube dispersion additives enhances the interaction with the aromatic nanotube scaffold in comparison to classical detergents where the interaction is limited to van der Waals attraction.
Claudia Backes

Chapter 4. Conclusion

The work presented here served the purpose to gain fundamental insights in noncovalent functionalization of single-walled carbon nanotubes. The focus was directed towards establishing structure–property relationships of adsorbates and nanotubes in aqueous solution in order to understand nanotube dispersion and exfoliation, especially by designed surfactants. Up to now, despite the extraordinary progresses in the development of nanotube sorting techniques, the efficiency of nanotube separation as a foundation for their increased processability has been restricted by the limited exfoliation efficiencies of commercially available detergents. This is exactly the point where this work hooked in and enabled to pave the way to improved sorting.
Claudia Backes

Chapter 5. Experimental Details

The purified HiPco> SWCNTs (Batch P0343, residual weight 5%) were purchased from Unidym Inc. (U.S>). In case of the covalently functionalized SWCNTs, the batch P0261 has been the used for further processing. Laser ablation SWCNTs (batch R0448) were obtained from Carbon Nanotechnology Inc. (U.S.). The purified CoMoCAT> SWCNTs (batch SG65-0012, residual weight 20%) were purchased from Southwest Nanotechnology Inc. (U.S.). All SWCNT> materials were used as received without further purification
Claudia Backes


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