Surface Aminated Modification And Characterization Of Nanodiamond

Detonation nanodiamond(DND) and broken high-temperature high-pressurenanodiamond (HTHP-ND) were amined by chemicals. Infrared spectroscopy andthermal gravimetric were used to analyze the surface structural characteristics.Particle size and zeta potential test were used to research the dispersion performanceof ND samples. The amination steps were followed: carboxyl functional group on NDsurface was changed into acyl chloride functional group which has a higher activityby thionyl chloride; then acyl chloride reactied with thylenediamine(EDA) to formsecondary amide bond(-CONH-). At the same time, another amino of EDA waslinked to ND surface, aminated ND was obtained. Oxidation treatment could increasethe content of carboxyl functional group on DND. Then, quantitative analyzed thecontent of ND surface carboxyl functional groups by Boehm titration. The mainconclusions obtained through research are followed:1. Content of carboxyl group on the DND surface was0.18mmol/g determinedby Boehm titration, which increased to be0.33mmol/g after oxidized. The content ofcarboxyl group on the HTHP-ND surface was0.21mmol/g;2. There ware a large amount of amino functional groups on aminated ND: Thepeaksa of1521cm-1in the IR spectra corresponded to secondary amide bond and thepeak of1665cm-1corresponded to blue shift of carbonyl in secondary amide bond,and the peak intensity increased with the amination time; The thermal weight losspeak of266oC in DTG corresponded to amino on aminated ND, which did notappeare in none-aminated ND, showed that ND connected with EDA by secondaryamide bond;3. Dispersion ability of DND in water had a substantially increase after aminatd,but the dispersion ability of HTHP-ND showed no obvious change after aminatd:DND sample falled soon in the water, but uniformly dispersed after aminated, and theaverage particle size was218nm. The isoelectric point of aminated DND was aboutpH=5, and absolute value of zeta potential reached maximum at about pH=10.3, which was-36.6mV. HTHP-ND sample had a good dispersion ability, the averageparticle size was178nm, which was193nm after aminated. The isoelectric point ofaminated HTHP-ND was about pH=6, and absolute value of zeta potential reachedmaximum at about pH=10.4, which was-41mV.