Molecular dynamics simulation of polystyrene copolymer with octyl short-chain branches in toluene
- 16 March 2020
- journal article
- research article
- Published by Springer Science and Business Media LLC in Journal of Molecular Modeling
- Vol. 26 (4), 1-14
- https://doi.org/10.1007/s00894-020-4339-2
Abstract
In this study, dimensional, conformational and dynamic behaviors of a short-chain branched styrene/1-octene copolymer chain with different 1-octene percentages, i.e., 0, 2, 4 and 6%, in toluene are investigated at the temperature of 298.15 K via molecular dynamics simulation. The chain dimensions and flexibility in the solvent are evaluated by calculating the radius of gyration (Rg), end-to-end distance (<r0>), surface area (Ach), and volume (Vch) of the copolymer chain. The mean square displacement (MSD) and diffusivity coefficient for each copolymer chain are measured to determine its dynamic behavior and mobility in aromatic media. To consider the effect of increasing the 1-octene co-monomer percentage on the copolymer chain affinity to the solvent molecules, the interaction energy (Eint) and Flory-Huggins (FH) interaction parameter are calculated for each equilibrated solution model. The simulation results indicate that the co-monomer level increment in the copolymer structure reduces the chain Rg amount and its interaction with the solvent. The <r0> of the chain increases up to 4% co-monomer content, while further co-monomer content decreases the <r0> value. Additionally, the viscosity of the equilibrated dilute solutions is calculated via non-equilibrium molecular dynamics simulation (NEMD). Moreover, the steric hindrance of the copolymers and the solvent molecules capturing in the dilute solution is determined via radial distribution function (RDF) analysis. Helmholtz free energy and the system entropy changes are calculated to evaluate the tendency of the copolymer to the solvent molecules and its dilute solution irregularity, respectively. The figure shows the variations trend of the poly(styrene-co-1-octene) chain dimensions in toluene aromatic solvent by increasing the 1-octene content (x), after the equilibration state. Red and blue colors represent the carbon atoms of the copolymer chain backbone and 1-octene side chains, respectively. The styrene rings and the hydrogen atoms of the chains were removed for better view.Keywords
This publication has 56 references indexed in Scilit:
- Molecular Dynamics Simulation Studies of Viscosity and Diffusion of n-Alkane Oligomers at High TemperaturesBulletin of the Korean Chemical Society, 2011
- Molecular simulation of CO2/CH4 permeabilities in polyamide–imide isomersJournal of Membrane Science, 2010
- Folding and Unfolding of Individual PNIPAM-g-PEO Copolymer Chains in Dilute Aqueous SolutionsMacromolecules, 2005
- Non-equilibrium molecular dynamics simulation of the shear viscosity of liquid methanol: adaptation of the Ewald sum to Lees-Edwards boundary conditionsMolecular Physics, 1997
- Molecular packing and small-penetrant diffusion in polystyrene: a molecular dynamics simulation studyPolymer, 1996
- Molecular Dynamics Computer Simulation of Polyisoprene Local Dynamics in Dilute Toluene SolutionMacromolecules, 1995
- Excluded-volume effects on the mean-square radius of gyration of oligo- and polystyrenes in dilute solutionsMacromolecules, 1993
- Excluded-volume effects on the intrinsic viscosity of oligomers and polymers of styrene and isobutyleneMacromolecules, 1993
- Non-Equilibrium Molecular Dynamics Calculation of the Shear Viscosity of Carbon Dioxide/Ethane MixturesMolecular Simulation, 1993
- Dynamics of dilute polymer solutionsMacromolecules, 1981