Nanodiamonds surface reactivity

One method of oxidizing nanodiamond surfaces has already been presented in Section 5.3.4 as a means of sample purification. The differing reactivity of graphitic and diamond carbon is utilized here. The unordered graphitic structures are oxidized and removed as gaseous products, whereas diamond particles are only modified on their surface. 

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 surface bromination occurs as a radical process with elemental bromine that is reacted with the nanodiamond as solution in chloroform. By the action of light, bromine radicals are generated to attack on the surface. For the reduced reactivity of bromine radicals, however, just a partial bromination is achieved, and the degree of surface covering remains comparatively low at 0.87 mmol g. ... 

---