Aqueous colloidal solution2.5 w/v %
Soft hydrogelabout 13 w/v ％
The concentration of our major product, aqueous solution, is increased from the previous 2.0% to more stable level of 2.5%, taking into account of a new characteristic in the nanodiamond solution called “Dilution Aggregation, Concentration Dispersion.” This interesting phenomenon will be mentioned in some detail in our next news.
[Dec.]Stable production of the elementary particles of detonation nanodiamond (EPDND) with an average diameter of 2.6nm achieved！We have begun distributing single-nano diamond particles in 2006, but never been sure if our products are perfectly monodispersed primarily because the elementary particle of detonation nanodiamond (EPDND) was unknown. If the strongest-bound oligomers like dimers and trimers were still present even in small amounts, we should expect lognormal distribution (which we actually observe all the time) and the average or modal diameter could shift to a larger value. In the absence of any handy method to detect oligomers, we adopted quality engineering technique to optimize the beads-milling conditions and reach the smallest possible diameter value. To our surprise, average diameter of EPDND began decreasing from our old value in the 4 nm range, and reached to below 3nm in 2013 for the first time. A key factor was revealed to be tremendous increase in the number of diamond particles in going from micron-sized agglutinates to single-nano particles. We will reveal our new methodology to find the true size of EPDND. During 2016, the size-distribution almost constantly showed a narrow range of 2.6±0.4 nm. We now presume that complete disintegration of the agglutinates has been accomplished.
The only problem remaining is to remove persistent contamination of zirconia nanoparticles (about 40 nm), which came from direct contact of the elementary diamond particles with the attritter media of zirconia, and are very difficult to remove by conventional chemical means. Although zirconia nanoparticles are generally harmless and non-toxic, and present in our nanodiamond product only in less than 0.01% on the number or volume basis, we are now testing several new methods of removing contamination and will soon finish purification.