Adhesion and Interface Properties of Polydopamine and Polytetrafluoroethylene Thin Films

2020 ◽  
Vol 87 (12) ◽  
Author(s):  
Matthew Brownell ◽  
Arun K. Nair
Keyword(s):  
Thin Films ◽  
Molecular Dynamics ◽  
Wear Rate ◽  
Density Functional ◽  
Md Simulations ◽  
Deformation Mechanisms ◽  
Adhesive Properties ◽  
Functional Theory ◽  
Ptfe Film ◽  
Scratch Tests

Abstract Polytetrafluoroethylene (PTFE) has been studied as a low friction surface coating since its discovery. The high wear-rate of PTFE reduces the usefulness of the polymer for mechanical purposes; however, combining PTFE with polydopamine (PDA) has been shown to greatly reduce the film wear-rate. During rubbing tests involving PDA/PTFE thin films, a tenacious layer of PTFE remains intact after substantial testing even though pure PTFE film layers are destroyed quickly. Understanding the interface mechanics that allow PTFE and PDA to adhere so well during experimental rubbing tests is necessary to improve the wear-rate of PDA/PTFE thin films. In this study, we use density functional theory (DFT) and molecular dynamics (MD) simulations to investigate the adhesive properties and interface deformation mechanisms between PDA and PTFE molecules. Steered molecular dynamics (SMD) is then performed on isolated pairs of PDA and PTFE molecules to investigate different modes of deformation from equilibrium. PDA trimer oligomers were identified as the most adhesive to PTFE and selected to use in a PDA/PTFE thin film, where nano-indentation and scratch tests are performed. Our results indicate that a combination of the unique deformation mechanisms of PDA molecules and the penetration of PTFE molecules into the PDA substrate provide the PTFE/PDA interface with its wear resistance.

scholarly journals Polydopamine and eumelanin molecular structures investigated with ab initio calculations

2017 ◽  
Vol 8 (2) ◽  
pp. 1631-1641 ◽  
Author(s):  
Chun-Teh Chen ◽  
Francisco J. Martin-Martinez ◽  
Gang Seob Jung ◽  
Markus J. Buehler
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Md Simulations ◽  
Molecular Structures ◽  
Brute Force ◽  
Functional Theory

A set of computational methods that contains a brute-force algorithmic generation of chemical isomers, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations is reported and applied to investigate nearly 3000 probable molecular structures of polydopamine (PDA) and eumelanin.

Energetics and diffusion of liquid water and hydrated ions through nanopores in graphene: ab initio molecular dynamics simulation

2017 ◽  
Vol 19 (31) ◽  
pp. 20551-20558 ◽  
Author(s):  
Raúl Guerrero-Avilés ◽  
Walter Orellana
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Functional Theory ◽  
Hydrated Ions ◽  
And Diffusion

The energetics and diffusion of water molecules and hydrated ions (Na+, Cl−) passing through nanopores in graphene are addressed by dispersion-corrected density functional theory calculations and ab initio molecular dynamics (MD) simulations.

Simulating Surfactant-Iron Oxide Interfaces: From Density Functional Theory to Molecular Dynamics

2019 ◽  
Author(s):  
Carlos Ayestaran Latorre ◽  
James Ewen ◽  
Chiara Gattinoni ◽  
Daniele Dini
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Iron Oxide ◽  
Dft Calculations ◽  
Density Functional ◽  
Md Simulations ◽  
Oxide Surfaces ◽  
Interaction Energies ◽  
Functional Theory ◽  
Oxide Interfaces

<div>Understanding the behaviour of surfactant molecules on iron oxide surfaces is important for many industrial applications. Molecular dynamics (MD) simulations of such systems have been limited by the absence of a force-feild (FF) which accurately describes the molecule-surface interactions. In this study, interaction energies from density functional theory (DFT) + U calculations with a van der Waals functional are used to parameterize a classical FF for MD simulations of amide surfactants on iron oxide surfaces. The Original FF, which was derived using mixing rules and surface Lennard-Jones (LJ) parameters developed for nonpolar molecules, were shown to signi cantly underestimate the adsorption energy and overestimate the equilibrium adsorption distance compared to DFT. Conversely, the Optimized FF showed excellent agreement with the interaction energies obtained from DFT calculations for a wide range of surface coverages and molecular conformations near to and adsorbed on a-Fe2O3(0001). This was facilitated through the use of a Morse potential for strong chemisorption interactions, modi fied LJ parameters for weaker physisorption interactions, and adjusted partial charges for the electrostatic interactions. The Original FF and Optimized FF were compared in classical nonequilibrium molecular dynamics (NEMD) simulations of amide molecules con fined between iron oxide surfaces. When the Optimized FF was employed, the amide molecules were pulled closer to the surface and the orientation of the headgroups was more similar to that observed in the DFT calculations compared to the Original FF. The Optimized FF proposed here facilitates classical MD simulations of amide-iron oxide interfaces in which the interactions are representative of accurate DFT calculations.</div>

Stabilization of DPPC lipid bilayers in the presence of co-solutes: molecular mechanisms and interaction patterns

2021 ◽  
Author(s):  
Fabian Keller ◽  
Andreas Heuer ◽  
Hans-Joachim Galla ◽  
Jens Smiatek
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Lipid Bilayers ◽  
Density Functional ◽  
Molecular Mechanisms ◽  
Md Simulations ◽  
Water Molecules ◽  
Interaction Patterns ◽  
Conceptual Density Functional Theory ◽  
Functional Theory

The interactions between DPPC lipid bilayers in different phases with ectoine, amino ectoine and water molecules are studied by means of atomistic molecular dynamics (MD) simulations and conceptual density functional theory (DFT) calculations.

C2N: an excellent two-dimensional monolayer membrane for He separation

2015 ◽  
Vol 3 (42) ◽  
pp. 21351-21356 ◽  
Author(s):  
Lei Zhu ◽  
Qingzhong Xue ◽  
Xiaofang Li ◽  
Tiantian Wu ◽  
Yakang Jin ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Md Simulations ◽  
Separation Performance ◽  
Two Dimensional ◽  
Functional Theory

Using the first-principles density functional theory (DFT) and molecular dynamics (MD) simulations, we investigate the He separation performance of a porous C2N monolayer synthesized recently.

Molecular motions in a fluxional (η6-indenyl)tricarbonylchromium hemichelate: a density functional theory molecular dynamics study

2018 ◽  
Vol 47 (27) ◽  
pp. 8906-8920 ◽  
Author(s):  
Nicolas Sieffert
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Density Functional ◽  
Md Simulations ◽  
Atomic Level ◽  
Molecular Motions ◽  
Comprehensive Understanding ◽  
Intramolecular Dynamics ◽  
Functional Theory

DFT-MD simulations provided atomic-level insights into the intramolecular dynamics of a highly fluxional Pd(ii) hemichelate and a comprehensive understanding of the thermodynamics and the kinetics associated with each motion.

scholarly journals Simulating Surfactant-Iron Oxide Interfaces: From Density Functional Theory to Molecular Dynamics

2019 ◽  
Author(s):  
Carlos Ayestaran Latorre ◽  
James Ewen ◽  
Chiara Gattinoni ◽  
Daniele Dini
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Iron Oxide ◽  
Dft Calculations ◽  
Density Functional ◽  
Md Simulations ◽  
Oxide Surfaces ◽  
Interaction Energies ◽  
Functional Theory ◽  
Oxide Interfaces

<div>Understanding the behaviour of surfactant molecules on iron oxide surfaces is important for many industrial applications. Molecular dynamics (MD) simulations of such systems have been limited by the absence of a force-feild (FF) which accurately describes the molecule-surface interactions. In this study, interaction energies from density functional theory (DFT) + U calculations with a van der Waals functional are used to parameterize a classical FF for MD simulations of amide surfactants on iron oxide surfaces. The Original FF, which was derived using mixing rules and surface Lennard-Jones (LJ) parameters developed for nonpolar molecules, were shown to signi cantly underestimate the adsorption energy and overestimate the equilibrium adsorption distance compared to DFT. Conversely, the Optimized FF showed excellent agreement with the interaction energies obtained from DFT calculations for a wide range of surface coverages and molecular conformations near to and adsorbed on a-Fe2O3(0001). This was facilitated through the use of a Morse potential for strong chemisorption interactions, modi fied LJ parameters for weaker physisorption interactions, and adjusted partial charges for the electrostatic interactions. The Original FF and Optimized FF were compared in classical nonequilibrium molecular dynamics (NEMD) simulations of amide molecules con fined between iron oxide surfaces. When the Optimized FF was employed, the amide molecules were pulled closer to the surface and the orientation of the headgroups was more similar to that observed in the DFT calculations compared to the Original FF. The Optimized FF proposed here facilitates classical MD simulations of amide-iron oxide interfaces in which the interactions are representative of accurate DFT calculations.</div>

Nitrogen-Modified Graphdiyne as a Promising Membrane for Helium Separation: First-Principles and Molecular Dynamics Simulations

2017 ◽  
Vol 381 ◽  
pp. 20-25 ◽  
Author(s):  
Jing Xu ◽  
Jing Li ◽  
Hai Jun Liu ◽  
Lian Ming Zhao
Keyword(s):  
Molecular Dynamics ◽  
First Principles ◽  
Density Functional ◽  
Strong Stability ◽  
Md Simulations ◽  
Separation Performance ◽  
Functional Theory ◽  
Gas Separation Membrane ◽  
Separation Membrane ◽  
Dynamics Simulations

The He separation performance of the N-modified graphdiyne monolayer (N-GDY) was studied by using both the first-principles density functional theory (DFT) and molecular dynamics (MD) simulations. The high cohesive energy of 7.24 eV/atom confirmed the strong stability of N-GDY for a gas separation membrane. Based on the calculations, the N-GDY membrane was found to exhibit extremely high He permeance (4.8 ×10-3 mol/m2·s·Pa at 100 K) and selectivities of He/H2O, He/Ar, He/N2, He/CO, He/CO2, and He/CH4 (102~1012 at 300 K). Therefore, N-GDY should be a good candidate for He separation from natural gas.

scholarly journals Investigation of the reactivity properties of a thiourea derivative with anticancer activity by DFT, MD simulations

2021 ◽  
Author(s):  
Sheena Mary ◽  
Y. Shyma Mary ◽  
Anna Bielenica ◽  
Stevan Armaković ◽  
Sanja J. Armaković ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Density Functional ◽  
Spectroscopic Analysis ◽  
Md Simulations ◽  
Distribution Functions ◽  
Solubility Parameters ◽  
Functional Theory ◽  
Quantum Molecular Descriptors ◽  
Combined Application ◽  
Local Reactivity

Abstract Spectroscopic analysis of 1-(2-fluorophenyl)-3-[3-(trifluoromethyl)phenyl]thiourea (FPTT) is reported. Experimental and theoretical analysis of FPTT, with Molecular Dynamics (MD) simulations, are reported for finding different parameters like: identification of suitable excipients, interactions with water, and sensitivity towards autoxidation. Molecular dynamics and docking show that FPTT can act as a potential inhibitor for new drug. Additionally, local reactivity, interactivity with water, and compatibility of FPTT molecule with frequently used excipients have been studied by combined application of density functional theory (DFT) and MD simulations. Analysis of local reactivity has been performed based on selected fundamental quantum-molecular descriptors, while interactivity with water was studied by calculations of radial distribution functions (RDFs). Compatibility with excipients has been assessed through calculations of solubility parameters, applying MD simulations.

THE ROLE OF SUBSTRATE IN PACKING STRUCTURES OF SEXITHIOPHENES ON AG (111) SURFACE: MOLECULAR DYNAMICS SIMULATIONS AND QUANTUM CHEMICAL CALCULATIONS

2009 ◽  
Vol 08 (04) ◽  
pp. 677-690 ◽  
Author(s):  
JIN WEN ◽  
JING MA
Keyword(s):  
Molecular Dynamics ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Md Simulations ◽  
Site Preference ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Dynamics Simulations

Packing structures and orientation of sexithiophene (6T) molecules on Ag (111) surface are investigated by molecular dynamics (MD) simulations and quantum chemical calculations. Both the cluster and the slab models are employed. The density functional theory and molecular mechanism calculations demonstrate a weak physisorption and little site-preference in thiophene/ Ag (111) system. The MD simulations show that in the first layer close to the surface, the nearly coplanar 6T strips lie parallel with long axes deviating from [Formula: see text] direction about 20° – 30° and 75° – 90°. The average adsorption height of the monolayer is about 3.2 Å with most of the sulfur atoms in thienyl rings sitting on the bridge site of Ag (111) surface. The 6T molecules tend to take tilted orientations when they are far away from the surface. The packing structures of 6T layers deposited on the surface resulted from the competition between the molecule–substrate and intermolecular interactions.

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