Biomedical Engineering Reference
In-Depth Information
What follows is a brief summary of the results of detailed TDMS
studies performed on UDD synthesized in different scientific centers.
All measurements were carried out under the same protocol in
order to ensure the possibility of quantitative comparisons. We
were trying to answer the following two key questions: (i) what are
the “fingerprints” left in UDD by different producers (certification),
(ii) is it possible to erase the “chemical memory” about the origin of
UDD (unification). Some results of the works were published in the
form of abstracts and regular papers [26, 58, 60-65].
6.3
Results of the Studies of Detonation
Nanodiamonds of Different Types
6.3.1
Objects and Methods
A number of UDD powders, produced by different scientific centers,
were used in this comparative study of their surface chemistry.
All samples were synthesized by the detonation of a mixture of
trinitrotoluene (TNT) and 1, 3, 5-trinitro-1, 3, 5-s-triazine (RDX) as
primary step. The samples used in this work differ in the details of
both the detonation synthesis and the chemical separation procedure
[26]. The powders have different colors, changing from brown to light
gray, depending on the UDD type. Also, the sedimentation stability
of aqueous colloidal solutions of UDD, an important factor for some
practical applications of UDD [66], was found to depend strongly on
nanodiamond type [26]. In some cases a total precipitation occurred
in few hours, for some samples the colloidal solution remained
stable during months [26].
The structure and chemical composition of as-received
samples of different types of UDD were characterized by means of
X-ray diffraction, IR and Raman spectroscopy, elemental analysis,
thermogravimetry, and TDMS.
Structure, Chemical Composition and Thermal
Stability of Various UDD
6.3.2
The X-ray diffraction analysis did not reveal noticeable differences
between crystal structures of the samples. The X-ray diffraction
patterns were similar to those observed in Ref. [67] and contained
