HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS

This article is devoted to the synthesis and characterization of the hydrosol of C70 of the son/nC70 type and to its coagulation by sodium chloride and cetyltrimethylammonium bromide (CTAB). At C70 concentration of 3.3×10–6 M, the electrokinetic potential is ζ= –40 ± 4 mV, the particle size expressed as Zeta-average is 97±3 nm; at higher C70 concentrations, 1.7×10–5 and 6.9×10–5 M, the size stays the same: 99 – 100 nm. The critical concentration of coagulation (CCC) values, were determined using the diameter increasing rate (DIR) on NaCl concentration. The CCCs are concentration-dependent: 250, 145, and 130 mM at C70 concentrations 3.3×10–6, 1.7×10–5, and 6.9×10–5 M, respectively. The CCC for the CTAB surfactant is much lower, about 5×10–3 mM. At 0.02 mM CTAB, however, the overcharging up to ζ = + 40 mV and stabilization of the colloidal particles take place. Interpretation of the hydrosol coagulation by NaCl using the Derjaguin–Landau–Verwey–Overbeek theory makes it possible to determine the Hamaker constant of the C70–C70 interaction in vacuum, if only electrostatic repulsion and molecular attraction are taking into account: AFF ≈ 7×10–20 J. On the other hand, if we use the value AFF = (16.0–16.6)×10–20 J, obtained earlier in the study of organosols, then the data for hydrosols can be explained only by the introduction of an additional type of interactions. Following the terms of Churaev and Derjaguin, one should take into account the structural contribution to the interaction energy, which stabilizes the hydrosol.

Theoretical Concepts of the Modification Effect on the Interparticle Energy of the Polymer-Mineral Dispersions for 3D Printing

The molecular gravity and electrostatic repulsion energies were calculated taking into account the structural forces between the modified particles of the polymer-chalk dispersion, which was chosen as a model polymer-chalk system when studying systems for the innovative construction industry using additive technologies (3D printing). In the above calculations, differences for the studied systems are taken into account in such quantities as the complex Hamaker constant, the ionic strength of the solution, and the diffuse layer potential. The calculation of the total potential curves of modified and unmodified polymer-chalk dispersions and the contribution of various factors of aggregative stability analysis showed that as a result of the adsorption of modifier molecules on the particles surface, the action of molecular attraction forces is overcome by the combined action of electrostatic and adsorption-solvate factors of aggregative stability.

Simulation of CO2 Adsorption to Enhance Adsorbent Material Efficiency

Computer simulation techniques have gained many attentions. The objective of this research was to study influence of the exchangeable cations of Group 1A (Li+, Na+, K+, Rb+, Cs+) on the CO2 adsorption in the system using Grand Canonical Monte Carlo (GCMC) simulation. In this simulation, zeolite is a simulation box. The interaction potential simulation with Lennnard-Jones potential showed that Li+ and CO2 had the greatest molecular attraction with Li+ having the highest number of CO2 molecules in the simulation box. The number of CO2/molecules in the simulation box are as followed with Li+ > Na+ > K+ > Rb+ > Cs+.

INVESTIGATION FOR MOLECULAR ATTRACTION IMPACT BETWEEN CONTACTING SURFACES IN MICRO-GEARS

The aim of this research work is to provide a systematic method to perform molecular attraction impact between contacting surfaces in micro-gear train. This method is established by integrating involute profile analysis and molecular dynamics simulation. A mathematical computation of micro-gear involute is presented based on geometrical properties, Taylor expression and Hamaker assumption. In the meantime, Morse potential function and the cut-off radius are introduced with a molecular dynamics simulation. So a hybrid computational method for the Van Der Waals force between the contacting faces in micro-gear train is developed. An example is illustrated to show the performance of this method. The results show that the change of Van Der Waals force in micro-gear train has a nonlinear characteristic with parameters change such as the modulus of the gear and the tooth number of gear etc. The procedure implies a potential feasibility that we can control the Van Der Waals force by adjusting the manufacturing parameters for gear train design.