Infrared absorption study of surface functional groups providing chemical modification of nanodiamonds by divalent copper ion complexes

Infrared (IR) absorption data evidence the presence of multiple carboxyl and anhydride groups together with hydroxyl and C(sp³)-H groups in the dried copper-modified detonation nanodiamonds (DND). Insignificant differences in IR spectra of initially purified and copper-modified nanodiamonds indicate that in the ion exchange process Cu²⁺ ions substitute protons just in a small fraction of the entire amount of carboxyl groups on the DND surface. Surface anhydride groups appear as the result of mutual conversion of the neighboring carboxyl groups into the anhydride ones. The observation of specific shape of IR absorption spectrum of DND is a good practical rule for primary selection of detonation nanodiamonds with oxygen-containing functional groups well suitable for targeted surface modification by double-charged metal ions.     

Effect of nanodiamond surface functionalization using oleylamine on the scratch behavior of polyacrylic/nanodiamond nanocomposite

Addition of hard particles such as nanodiamonds to polymers to improve their physical and mechanical properties is very common. However, nanodiamonds are usually hydrophilic so their tendency to form agglomerates in a polymeric matrix is quite strong. In this study, the effect of nanodiamond surface modification on its uniform dispersion in a polymeric matrix such as polyacrylic-base polymer clear coat was investigated. For this purpose, detonation nanodiamond (DND) with an average particle diameter of 4–6 nm was used. To improve dispersion of as-received DND (AR-DND) in the polymeric matrix, the surfaces of the particles were modified by heat treatment (oxidation) in air and followed by functionalization using oleylamine (OLA) as surfactant. So, nanocomposites with different contents of AR-DND, HT-DND and OLA treated HT- DND (OLA-HT-DND) particles were produced. Their characterizations were investigated by employing many analytical methods such as: Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermo-gravimetry analysis (TGA). Scratch resistance test and study of coating surfaces, using scanning tunneling microscopy (STM), were carried out on the polymeric nanocomposites. The results showed that the surface-functionalized nanodiamonds are highly dispersive and stable in the polymeric matrix. In addition, scratch resistance was increased with the addition of nanoparticles.     

Detonation nanodiamonds as UV radiation filter

The attenuation of ultraviolet radiation (UVR) by detonation nanodiamonds (DND) can be significant, depending on the concentration, composition of DND surface, size of DND particles and content of nitrogen defects in DND. The ability of DND to attenuate efficiently UVA (320–400 nm), UVB (290–320 nm) and UVC (190–290) radiation via absorption and scattering makes them attractive broad-spectrum UV-protecting agents. The studied DND exhibited red photoluminescence presumably due to the nitrogen-vacancy centers.     

Onion-like carbon for terahertz electromagnetic shielding

It is demonstrated that onion-like carbon (OLC) provides efficient attenuation of the electromagnetic spectrum over the wavelength range 12–230 THz as compared to detonation nanodiamonds (DND) at similar or higher concentrations. Some characteristics of OLC important for the processing of polymer composites such as surface functional groups, zeta-potentials and agglomerate sizes are reported.     

Thermochemistry of nanodiamond terminated by oxygen containing functional groups

The standard enthalpies of formation at 25 °C of nanodiamonds terminated by oxygen containing functional groups have been investigated by high-temperature oxidation calorimetry. Depending on the amount of oxygen containing functional groups, the nanodiamonds (plus oxygen and hydrogen as represented in the surface functional groups) can be up to 52 kJ mol⁻¹ more stable in enthalpy than graphite, which means that less heat is evolved during oxidation of nanodiamonds terminated by oxygen containing functional groups, since their surface carbon is already partially oxidized. The stability of the nanodiamonds terminated by oxygen containing functional groups increases (enthalpy of formation becomes more negative) with increasing surface area within the studied range, reflecting the dominant effect of higher content of surface functional groups over the destabilizing effect of higher surface-to-volume ratio typical for nanoparticles.     

Fluorinated‐plasma modification of polyetherimide films

Ultem 1000 polyetherimide films prepared by cast-evaporating technique were covered with a 1H,1H,2H-tridecafluoro-oct-1-ene (PFO) plasma-polymerized layer. The effects of the plasma exposure time on the surface composition were studied by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and surface energy analysis. The surface topography of the plasma layer was deduced from scanning electron microscopy. The F/C ratio for plasma-polymerized PFO under the input RF power of 50 W can be as high as 1.30 for 480 s and ∼0.4–2 at % of oxygen was detected, resulting from the reaction of long-lived radicals in the plasma polymer with atmospheric oxygen. The plasma deposition of fluorocarbon coating from plasma PFO reduces the surface energy from 46 to 18.3 mJ m⁻². © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3579–3588, 2006     

Effect of Modification of Tetryl Detonation Nanodiamonds on Combustion of Model Paste-Like Propellants

Combustion, Explosion, and Shock Waves - Detonation nanodiamonds (DND) represent a unique material combining the properties of a rather passive diamond core with an active carbon shell. The effect...     

水溶性酚醛树脂制备超级电容器用活性炭

以苯酚和甲醛为原料,氢氧化钠为催化剂,采用两步碱催化合成工艺,制备了水溶性酚醛树脂前驱体。使前驱体在高温下炭化,制备出以介孔为主的活性炭。将活性炭在2.5 mol•L^-1 HNO₃溶液中进行活化后得到产品。所得产品的物理性质用红外光谱（IR）、扫描电镜（SEM）和比表面（BET）测试进行表征。结果显示活化后活性炭比表面积略有下降,平均孔径变宽,但因活化增加了活性炭含氧官能团的含量,使得活性炭表面有效比表面积增加。电化学测试结果表明活化后的活性炭电极比容量增加,达到250 F•g^-1。     

Grain-boundary heat conductance in nanodiamond composites

Sintering of detonation nanodiamonds (DND) has been studied at a pressure of ～ 7 GPa in the 700–2000 °C temperature range. The X-ray coherent-scattering regions in DND have been found to grow with increasing sintering temperature. It is shown that diamond crystallites grow by the oriented attachment mechanism. It is demonstrated that the increase of thermal conductivity of the composites thus obtained is initiated by variation of the heat conductance of the boundaries separating DND crystallites.     

机械活化强化甘蔗渣铝酸酯表面改性

采用自制搅拌球磨机对甘蔗渣进行机械活化预处理,以改性甘蔗渣的活化度、润湿接触角及甘蔗渣/液体石蜡体系黏度为评价指标,分别研究了铝酸酯用量和机械活化时间对甘蔗渣改性效果的影响,并采用XRD、FTIR对甘蔗渣和改性产物进行了表征。研究结果表明：经铝酸酯处理后甘蔗渣的活化度、接触角增加,与液体石蜡体系的黏度降低,当铝酸酯用量为3%时效果最佳;机械活化明显强化了甘蔗渣与铝酸酯的反应,铝酸酯改性机械活化甘蔗渣的接触角和活化度明显增加,与液体石蜡组成的体系黏度降低,当机械活化120 min时效果最佳;甘蔗渣经表面偶联改性后,在有机相中的分散性明显增加,铝酸酯改性机械活化甘蔗渣效果更为显著;X射线衍射分析表明,机械活化降低了甘蔗渣纤维结晶度,提高了其对铝酸酯的反应活性;FTIR分析表明,甘蔗渣表面的羟基与铝酸酯中的烷氧基团发生化学反应,有新的官能团Al-O-C产生,并在甘蔗渣表面形成一层铝酸酯分子层。     

Absorption and scattering of light in nanodiamond hydrosols

Scattering and absorption of optical radiation in hydrosols of detonation nanodiamonds (DND) have been studied. Experimental data are presented on the spectral response of the optical density of DND hydrosols prepared by different techniques and in different concentrations. The size distribution of DND particles in these hydrosols was investigated by dynamic light scattering (DLS). The experimental data are compared with calculations. The calculations were performed on models including both the structure of a single DND particle made up of a diamond core and a thin graphite-like shell and the size distribution of the DND particles. A comparison of experiments with the calculation provided a possibility of refining the model of the DND particle and gaining insight into the nature of particle aggregation. It is demonstrated that the combined use of two methods of investigation, which deal with the spectral response of optical density and dynamic light scattering, offers valuable information on the nature of DND hydrosol coloring and the results of particle size determination.     

Nuclear spin-lattice relaxation in nanocarbon compounds caused by adsorbed oxygen

Nuclear spin-lattice relaxation measurement is an effective tool for studying electronic structure and magnetic properties of nanosized compounds. The present work deals with the effect of oxygen molecules, adsorbed onto the surface of carbon nanoparticles - in which the number of surface atoms is comparable with that in the sample's volume - on nuclear spin-lattice relaxation rate of the carbon nuclei. We measured ¹³C spin-lattice relaxation in as-prepared (air rich) and out-gassed samples of detonation nanodiamond (DND), activated carbon fibers (ACF) and glassy carbon (GC) samples having multishell onion-like structure.Our measurements showed that the paramagnetic oxygen molecules (the only magnetic agent in ambient air), being physisorbed onto the surface and in structural voids of ACF and GC, create an additional relaxation channel and definitely affect the ¹³C spin-lattice relaxation as do the unpaired electrons of the internal dangling bonds. Air removal results in 1.5-2 times elongation in T₁. In contrast, the relaxation time is nearly the same for as-prepared and out-gassed DND samples. The reason is that in DND oxygen molecules have access only to the surface carbon nuclei whereas the rest of carbons remain unaffected by oxygen. Thus the main relaxation agents in DND particles are dangling bonds with unpaired electron spins, which mask the relaxation effect of paramagnetic oxygen. These findings are in a good agreement with our EPR data, which show that oxygen affects the inherent paramagnetic defects in the aforementioned nanocarbons.     

Structural study of detonation nanodiamonds

The structure of spherical hollow detonation nanodiamonds (DND) previously ground in a planetary mill for 10 min has been studied by synchrotron radiation diffraction. The interference contribution of the diffraction pattern from DND calculated using different structural parameters has been compared with the experimental pattern of DND after mechanical treatment. It was shown that after mechanical treatment of spherical hollow DND (r_inner=19.94 A, r_outer=25.47 A), two kinds of particles were observed: one was non-hollow spheres of r=13.9 A size at the same lattice parameters a=b=3.85 A, c=3.45 A and the others, of the size 5a×13b×5c at the parameters a=c=3.567 A, b=3.85 A, were particles of non-spherical shape.     

Thermal properties of phosphorylated nanodiamond reinforced polyimides

Recently, the preparation of nanodiamond–polymer composites has attracted the attention of materials scientists due to the unique properties of nanodiamonds. In this study, novel polyimide (PI)/phosphorylated nanodiamonds (PNDs) composites were prepared. PNDs were achieved from the reaction of methylphosphonic dichloride with nanodiamonds in dichloromethane. Precursor of polyimide, which is the poly(amic acid) (PAA), was successfully synthesized with 3,3′, 4,4′‐benzophenonetetracarboxylic dianhydride and 4,4′‐oxydianiline in the solution of N,N‐dimethylformamide. Different ratios of phosphorylated nanodiamond particles were added into PAA solution and four different nanocomposite films were prepared. The amount of PNDs in the composite films was varied from 0 wt% to 3 wt%. The structure, thermal and surface properties of polyimide films were characterized by scanning electron microscopy (SEM), ATR‐FTIR, thermogravimetric analysis (TGA), ultraviolet visible spectroscopy, and contact angle. SEM and FTIR results showed that the phosphorylated nanodiamond and PI/PNDs films were successfully prepared. Phosphorylated nanodiamonds were homogeneously dispersed in the polymer matrix and they displayed good compatibility. TGA results showed that the thermo‐oxidative stability of PI/PNDs films was increased with the increasing amount of phosphorylated nanodiamond. POLYM. COMPOS., 37:2285–2292, 2016. © 2015 Society of Plastics Engineers     

Locating inherent unpaired orbital spins in detonation nanodiamonds through the targeted surface decoration by paramagnetic probes

Detonation nanodiamond (DND) produced by explosive method has been successfully modified by divalent copper ions via their exchange with protons of neighboring carboxyl groups in water suspension. These ions interact magnetically with all diamond defect sites (both surface and bulk) causing changes in parameters of electron paramagnetic resonance (EPR) signal originating from spins (S = 1/2) of dangling C-C bonds — i.e. unpaired lone orbital paramagnetic centers (PC). EPR on the series of well purified aggregated and disintegrated DND samples in powders and suspensions showed that EPR parameters of PC in DND are unique features characterizing the nanodiamond particle as an isolated object. Surface Cu²⁺ ions located on the DND surface have been used for probing the location of PC. Double component analysis of PC's EPR spectra showed quasilinear dependence of line broadening for both EPR spectra components on probe concentration. The concentration changes for the broader component were found to be more prominent than that for the narrower one. It allows attributing PC characterized by the broader and narrower components to different types of defects located closer to the DND surface and deeper towards the diamond core. The estimated depths of occurrence for two types of intrinsic PC are ~ 0.8 nm and ~ 1.5 nm from the DND surface for the shallow and deeper PC, respectively.     

Sulfonation of pyropolymeric fibers derived from phenol-formaldehyde resins

This research demonstrates that pyropolymeric fibers derived from phenol-formaldehyde resins can be successfully sulfonated providing advantages that are not currently available with traditional polymeric ion-exchangers. Benefits of this system include higher thermal stability, elimination of osmotic shock associated with beads, and enhanced ion-exchange capability. In this study, a series of thermally and chemically activated fibers were prepared by heating a phenolic precursor under inert atmosphere at temperatures between 350 and 600 °C. Subsequent sulfonation of the fibers in concentrated sulfuric acid incorporated sulfonic acid units as well as various oxygen-containing groups. The identification of functional groups and their thermal stability was carried out using elemental analysis (EA), diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), and thermal gravimetric analysis (TGA). The effect of sulfonation on pore volume and surface area is discussed. Functional groups added during the sulfonation process serve as either strong acid or weak acid cationic exchangers.     

Fabrication of PFO‐DBT:OXCBA nanostructured composite via hard template

Poly[2,7‐(9,9‐dioctylfluorene)‐alt−4,7‐bis(thiophen‐2‐yl)benzo‐2,1,3‐thiadiazole] (PFO‐DBT) and o‐xylenyl‐C₆₀‐bisadduct (OXCBA) nanostructured composite has been fabricated via the hard porous alumina template‐directed method. Spin‐coating technique at the spin rate of 1000 rpm is used to assist the infiltration of polymer solution into porous template. PFO‐DBT nanotube is fabricated by replicating the porous alumina template before the formation of PFO‐DBT:OXCBA nanostructured composite. Formation of nanostructured composite is completed once the infiltration of OXCBA solution into PFO‐DBT nanotubes is achieved. Detailed results of morphological, structural, and optical properties of PFO‐DBT nanostructures (nanorods and nanotubes) of different solution concentrations are reported. By tuning the optical properties of PFO‐DBT nanostructures, the effect of solution concentration on the optical properties can be realized. The promising PFO‐DBT nanotubes are chosen for the further fabrication of OXCBA:PFO‐DBT nanostructured composite that acts as a core and shell, respectively. Although the nanostructured composite of PFO‐DBT:OXCBA yield low light absorption intensity, the absorption spans the whole visible region and produce low optical energy gap. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44228.     

Dual‐bonding structured ternary composite film of poly(vinyl alcohol)–boric acid–nanodiamond

Ternary composite films of poly(vinyl alcohol) (PVA), boric acid (BA), and detonation nanodiamond (DND) were prepared by aqueous solution method. Because of its excellent mechanical/thermal properties and low friction coefficient, DND is expected to offer PVA film superior performance if the puzzles of particle agglomeration in polymer matrix and fragile interface reaction between DND and PVA can be settled. BA was used as a crosslinking agent to form a strong network structure between DND and PVA. Investigation on microstructure of PVA/BA/DND films and bonding mechanisms therein shows that BA, DND, and PVA may crosslink by oxo‐bridges owing to the interaction of hydroxyl groups. The Young's modulus (E) of composite films was enhanced by nearly 3.3 times with only 0.8 wt % DND loading, and the antiwear, thermal stability, and waterproof properties can be significantly improved after the crosslinking. Meanwhile, the transparency of composite films can be well preserved even with large DND content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45449.     

Survey study of mercury determination in detonation nanodiamonds by pyrolysis flameless atomic absorption spectroscopy

A set of 20 commercially available nanodiamond samples of eight manufacturers of various countries, which are most frequently used in basic and applied studies, was analyzed for the concentration of Hg. Conditions of mercury determination by flameless atomic absorption spectroscopy with thermal sample decomposition (pyrolysis) at 800 °C were proposed and confirmed by wavelength-dispersive X-ray fluorescence analysis. It was found that nanodiamonds have a significant diversity of amounts of mercury, from 20 μg/kg to higher than 0.7 g/kg. Thus, the need to control Hg impurity in nanodiamonds, especially for biological and medical research, was demonstrated. The precision of flameless pyrolysis atomic absorption determination of mercury in nanodiamonds is discussed.     

In vitro monocyte adhesion and activation on modified FEP copolymer surfaces

The functional group content and the ionic state of functional groups present on a series of surface modified poly(tetrafluoroethylene/hexafluoropropylene) (FEP) copolymers were characterized by electron spectroscopy for chemical analysis (ESCA), contact angle, and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Additionally, after a protein was preadsorbed on these surfaces, in vitro cell (monocyte) adhesion and activation were analyzed. The two proteins in this study were fibrinogen and immunoglobulin-G (IgG). Four modified FEP surfaces were prepared with increasing concentration of carboxyl groups relative to amide groups; ESCA was used to quantify the functional group content. To characterize the ionic state of the functional groups at physiological pH (7.1), the ATR-FTIR spectra were collected at various pH levels. Collectively, the contact angle, ESCA, and ATR-FTIR results suggested that the amide groups were unprotonated and the carboxyl groups were ionized at the physiological pH. The results from the in vitro studies showed that on the fibrinogen preadsorbed surfaces, monocyte adhesion was higher and monocyte activation was lower on the three surfaces that contained carboxyl groups compared to the FEP surface that had only amide groups. Conversely, the results indicated that the surface chemistry had no significant effect on monocyte adhesion or activation on the IgG preadsorbed surfaces. © 1995 John Wiley & Sons, Inc.