10-80nm Detonation Nanodiamond Suspensions
Colloidal suspensions of detonation nanodiamond (DND) in both water and a variety of organic solvents have a wide range of uses, including: (1) drug delivery research, (2) nanocomposite strengthening, (3) electroplating, (4) polishing, and (5) oil and fuel additives. Adámas offers a selection of nanodiamond particle suspensions ranging in size from the fully deagglomerated monodispersed 4-5 nm primary particles up to 200 nm tight aggregates of the primary particles. See below characteristics for 10 – 80 nm nanodiamond suspensions.
Technical Characteristics
Particles with sizes above the primary 5 nm particles of detonation nanodiamond do not exist as monolithic diamond particles. This is an important distinction from other nanoparticle systems and even other types of diamond (such as particles produced by high pressure high temperature (HPHT) method). Detonation nanodiamonds at these sizes exist as tight, semi-porous clusters of 5 nm primary particles. Adámas offers between 10 nm and 50 nm aggregates of carboxylated DND (negatively charged with zeta potential -45 mV) as well as 80 nm positively charged product with polyfunctional groups (with zeta potential +40 mV). Dynamic light scattering based size distributions for these products are shown in Figure 1. All of these products are sold as suspensions in DI water.
Figure 1. Volumetric DLS size distributions of DND suspensions in water.
Featured Applications
Nanodiamond as a surfactant for carbon nanotubes
ND smaller fractions are excellent surfactants for other nanocarbon materials, such as carbon nanotubes and graphene (U.S. patents 8,070,988 & 8,308,994). Most sp2 carbon nanostructures including carbon nanotubes are hydrophobic and unstable in polar solvents without special surface functionalization (Figure 2a). Nanodiamonds however can stabilize colloidal suspensions of multi-wall carbon nanotubes (MWCNTs) and single-wall carbon nanotubes (SWCNTs) (Figure 2b).
By adding suspensions of nanodiamond particles with either positive or negative zeta potential to otherwise unstable aqueous suspensions of CNTs and sonicating the nanocarbon mixture for a few minutes, suspensions of SWCNTs and MWCNTs have been produced maintaining colloidal stability for several weeks and months, correspondingly. Nanodiamond/ carbon nanotubes mixtures are also stable in methanol, isopropanol, DMSO, and DMF.
The mechanism for nanodiamond-assisted dispersion of carbon nanotubes and graphene includes formation of π–π bonding between sp2 patches on nanodiamond and sp2 carbon atoms on CNT and graphene surfaces, decorating the surfaces. Since nanodiamond particles are highly charged in polar solvents, the sp2 nanocarbons interdigitated with charged nanodiamond particles also acquire high repulsive forces and resist agglomeration. During sonication nanodiamonds also cause debundling of CNTs or graphene constituents. Charged nanodiamond particles can be used to effectively and uniformly disperse the carbon nanotubes or graphene in a polymer matrix, leading to a very homogenous film (Figure 3).
Figure 2. Photographs showing the colloidal stability of suspensions for SWCNT and MWCNT in water without (a) and with DNDs (b).
Figure 3. Excellent uniformity of CNT distribution within a polymer film can be obtained with assistance of NDs
