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In this work, a molecular dynamic (MD) simulation method was employed to study the interfacial binding between the single-walled carbon nanotubes (SWCNTs) and some polymers and copolymers. The polymers studied include poly(vinyl pyrrolidone) as hydrophilic and poly(vinyl acetate) as hydrophobic polymers and also copolymers consisting of a series of vinyl pyrrolidone and vinyl acetate copolymers with different homogeneities in the backbone. The copolymers investigated have different structures and include alternative, diblock and triblock copolymers. This study has computed the intermolecular interaction energies between SWCNTs and polymers/copolymers in order to assess the effects of compositional heterogeneity on the interfacial binding between SWCNTs and polymers/copolymers. Also, the morphology of polymers/copolymers adsorbed to the surface of nanotubes has been studied. The obtained results showed that the intermolecular interactions in the simulated systems are strongly influenced by the monomer sequence distribution of hydrophilic and hydrophobic monomers in copolymers. The different values of intermolecular interaction energy for copolymers with identical numbers of hydrophilic and hydrophobic monomers but with different distributions suggest that an efficient load transfer through the interface between nanotube and copolymers is highly dependent on compositional heterogeneity of copolymers. Furthermore, we obtained the plots of the radial distribution function and the radius of gyration in order to study the effects of compositional heterogeneity on behavior of the studied nanocomposites. The results of the radial distribution function and the radius of gyration are in agreement with the findings of interfacial binding between SWCNTs and polymers/copolymers.

Adsorption and separation of binary mixtures of noble gases including Argon (Ar), Krypton (Kr), and Xenon (Xe) on (10,10) single-walled carbon nanotube (SWCNT) bundles is simulated by extensive equilibrium molecular dynamics (MD). Adsorption energies, diffusion coefficients, activation energies, and radial distribution functions (RDFs) were calculated to address the thermodynamics, transport and structural properties of adsorption process. The simulation results of exposing Ar–Kr, Ar–Xe, and Kr–Xe mixtures on (10,10) SWCNT bundles at temperatures of 75, 150, and 300 K, show that amount of adsorption is strongly influenced by the applied temperature. On the other hand, RDF plots show obviously that separation of binary gaseous mixture is occurred, where the heavier noble gas is adsorbed more than the lighter one in a selective manner by bundle. It is seen that the increase in the applied temperature results in more separation. These findings provide us a possible application of carbon nanotubes (CNTs) as efficient nanomaterials for separation and storage of gas mixtures.

In this work the behavior of the (8,2) single walled carbon nanotubes (CNTs) and functionalized carbon nanotubes (FCNTs) with four functional groups in water were studied using molecular dynamic (MD) simulation method. Glutamine as a long chain functional group and carboxyl as a short chain functional group have been used as functional groups in FCNTs. Four functional groups in each FCNT were localized at two positions: (i) all four functional groups were in the sidewalls of nanotube, (ii) two functional groups were at the ends and two functional groups were in the sidewalls of nanotube. The intermolecular interaction energies between CNTs or FCNTs and water molecules, the plots of radial distribution function and the diffusion coefficients of CNTs and FCNTs in water were computed for investigating the effects of type and position of functional groups on the behavior of FCNTs in water. The obtained results from three methods are consistent with each others. Results showed that the position of the functional groups in FCNTs has an important role in the interaction of hydrophilic groups of FCNTs with water molecules. Furthermore we also investigated the behavior of FCNTs with sixteen carboxyl functional groups in water. The presence of these large numbers of carboxyl functional groups on the carbon nanotubes prevents water molecules from moving towards hydrophilic carboxyl functional groups. This demonstrates the advantage of using lower number of functional groups each containing many hydrophilic groups like glutamine functional group.

Using molecular dynamics (MD) simulations, neon adsorption on an open-ended (10,10) single-walled carbon nanotube (SWCNT) was investigated at supercritical temperatures of neon, i.e. T=50, 70, and 90 K. Adsorption isotherms, heat of adsorption, self-diffusion coefficients, activation energy, and structural properties of neon gas were computed and analyzed in detail. All adsorption isotherms are predicted to be of Langmuir shape type І at this range of temperature. The results show that temperature is in a direct correlation with adsorption capacity, i.e. increase in temperature causes lower adsorption of neon gas by SWCNT. All aforementioned quantities confirm this fact and are in good agreement with previous experimental and theoretical works.