Nanodiamond surface modification

Mochalin VN, Osswald S, Portet C, Yushin G et al (2008) High temperature functionalization and surface modification of nanodiamond powders. Mater Res Soc Symp Proc 1039 1039-P11-03... 

A modification of functional groups already attached to the nanodiamond surface is of considerable interest for the development of new diamond materials for biomedical or mechanical applications. 

For C-based QDs, nanodiamond and carbon dots are most extensively reported. Synthesis techniques include surface modification, oxidation with concentrated acid, electrochemistry, laser ablation, organic carbonization, and template methods. ... 

Surface modification of nanomaterials has been the subject of much interest in recent years [180]. Some of these modifications have been performed by diazonium chemistry and include nanoparticles, nanodiamonds, fullerene, carbon nanotubes, and graphene (Table 3.7). 

In comparison to bulk diamond, nanodiamond particles are distinctly more reactive. This may be explained by the larger number of defects and by a markedly enlarged surface. Both effects increase the number of potential sites for the attack of a reagent, thus facihtating chemical modifications of nanodiamond particles. These include not only a functionalization of the surface, but also a conversion into other forms of carbon as discussed in Section 5.5.3. Due to the defective structure and to the presence of small graphitic domains on the particle surface, these transformations as well proceed much easier here than with macroscopic diamond particles. 

The carboxyl groups available from oxidation of the diamond surface also represent good anchoring sites for further functionalizations. Derivatives can be obtained by acid-catalyzed esterification as well as by a base-catalyzed formation of amides (Figure 5.41). Employing bifunctional alcohols or amines allows for subsequent grafting steps. In principle, the same compounds can be used here like in the modification of chlorinated nanodiamond with alcohols or amines. 

Furthermore, nanodiamond is suitable to applications in liquid chromatography. A directed modification of surface polarity and adsorptive properties is feasible here by functionalization of the particles. Apart from this versatility, the nanodiamond material also stands out for another advantage the large mechanical resistance and the small particle size allow a use in high-pressure applications, which is where the best separating power is achieved. 

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