Deagglomeration and surface modification of thermally annealed nanoscale diamond

Thermally annealed nanodiamond has been functionalized by C–C coupling of the partially graphitized diamond surface using aryl diazonium salts. Depending on the terminal functional groups, the modified bucky diamond nanoparticles show good solubility (up to 0.63 mg mL−1) in different solvents. The agglomerate size of the originally strongly bound detonation diamond (>0.5 μm) is substantially reduced to ∼20–50 nm by this chemical procedure and without using mechanical techniques such as strong ultrasound or milling. Arylation with functionalized aryl diazonium salts carrying COOH, SO3H, NO2 or bromoethyl groups opens the way for further covalent grafting of organic structures. Arylation with Ar–COOH or Ar–SO3H leads to the formation of stable colloidal solutions in water and physiological media (i.e. PBS buffer), an important prerequisite for biomedical applications.

Thermally annealed nanodiamond is surface arylated. The established terminal groups are sites for the grafting of larger moieties but also achieve the chemical deagglomeration of the material in various solvents.Figure optionsDownload high-quality image (52 K)Download as PowerPoint slideResearch highlights
► Nanodiamond is deagglomerated using thermal annealing and surface functionalization.
► sp2 carbon on diamond readily reacts with diazonium salts.
► Stable C–C bonds are formed by arylation of nanodiamond.
► ND solubility can be tuned by selecting suitable terminal groups.