Formation of Polyimide Membranes via Non-Solvent Induced Phase Separation: Insight from Molecular Dynamics Simulations.

Molecular dynamics simulations were applied to investigate the formation of P84 polyimide membranes through the non-solvent induced phase separation (NIPS) process, considering two scenarios: one using a conventional organic solvent like n-methyl-2-pyrrolidone (NMP) and the other a greener alternative, γ-butyrolactone (GBL), with water serving as the non-solvent. Different compositions of polymer solutions were established along the binodal boundaries of the respective systems, derived from experimental cloud point data on the ternary phase diagram. The resulting polymer membranes were analyzed and compared in terms of their morphology.

Solvent-Assisted Graphene Exfoliation from Graphite Using Umbrella Sampling Simulations.

We employed molecular dynamics (MD) simulations coupled with umbrella sampling to explore the thermodynamics governing the exfoliation of a single graphene layer from a graphitic substrate in five different solvents such as dimethylacetamide (DMA), -methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), cyclohexane (CHX), and water. The substrate was modeled as a stack of three identical graphene layers with the graphene sheet undergoing exfoliation positioned on top of this stack. The initial configurations for each umbrella simulation were generated through steered MD simulations carried out along two distinct coordinates: one parallel and the other perpendicular to the graphene layers.

Umbrella Sampling Simulations of Carbon Nanoparticles Crossing Immiscible Solvents.

We use molecular dynamics to compute the free energy of carbon nanoparticles crossing a hydrophobic-hydrophilic interface. The simulations are performed on a biphasic system consisting of immiscible solvents (i.e.

On the Consistency of the Exfoliation Free Energy of Graphenes by Molecular Simulations.

Monolayer graphene is now produced at significant yields, by liquid phase exfoliation of graphites in solvents. This has increased the interest in molecular simulation studies to give new insights in the field. We use decoupling simulations to compute the exfoliation free energy of graphenes in a liquid environment.

Binding Free Energy Calculations of Bilayer Graphenes Using Molecular Dynamics.

Bilayer graphenes are dimeric assemblies of single graphene layers bound together by π-complexation interactions. Controlling these assemblies can be complicated, as the layered compounds disperse in solvents or aggregate into higher columnar configurations and clusters. One way to assess the interactions that contribute to the stability of the layered compounds is to use molecular simulation.

Enhancement of Flux Performance in PTFE Membranes for Direct Contact Membrane Distillation.

This work focused on enhancing the flux on hydrophobic polymeric membranes aimed for direct contact membrane distillation desalination (DCMD) process without compromising salt rejection efficiency. Successful coating of commercial porous poly-tetrafluoroethylene membranes with poly(vinyl alcohol) (PVA) was achieved by solution dipping followed by a cross-linking step. The modified membranes were evaluated for their performance in DCMD, in terms of water flux and salt rejection.

Calculating adsorption isotherms using Lennard Jones particle density distributions.

The computation of particle density distributions in pore channels is a fundamental post process practice in molecular adsorption simulations. The distributions, although not appropriate for direct experimental interrogation, when expressed in variable temperature, may be used to evaluate thermodynamic properties. As with molecular simulations, we can spotlight any frame or region of interest inside the computational cell, the distributions and subsequently the thermodynamic evaluations can be pore or site specific.

The effect of gme topology on multicomponent adsorption in zeolitic imidazolate frameworks.

We employ a simulation approach to study the adsorption of single, binary and ternary mixtures on eight gme Zeolitic Imidazolate Frameworks (ZIFs) at 298 K. Four adsorbate fluids were considered; carbon dioxide, methane, nitrogen and water. We compute the high pressure adsorption density profiles inside the micropore channels of each crystal.