Molecular dynamics simulation of polystyrene copolymer with octyl short-chain branches in toluene
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ORIGINAL PAPER
Molecular dynamics simulation of polystyrene copolymer with octyl short-chain branches in toluene Sajad Rasouli 1 & Mohammad Reza Moghbeli 1
&
Sousa Javan Nikkhah 1
Received: 19 September 2019 / Accepted: 4 March 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
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 (), 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 of the chain increases up to 4% co-monomer content, while further co-monomer content decreases the 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. Keywords Chain dynamics . Dilute solution . Molecular dynamics simulation . Poly(styrene-co-1-octene) . Thermodynamic properties
Introduction The thermodynamic behavior of polymer solutions and the affinity of polymers to solvents have attracted the interest of scientists and industries [1, 2]. For instance, the solvent and oil absorption phenomenon using a cross-linked polymer network with a high capacity depends on its compatibility with solvent molecules. Some researchers studied the effect of polymer molecular composition and its affinity on the sorption of different solvents and its spill oil recovery [3–11]. Ceylan et al. [4] studied the aromatic hydrocarbon absorption from
* Mohammad Reza Moghbeli [email protected] 1
Smart Polymers and Nanocomposites Research Group, School of Chemical Engineering, Iran University of Science and Technology, Tehran 16846–13114, Iran
seawater using butyl rubber. Their results showed that the use of the rubber was more efficient than that of polypropylene in oil absorption process. Lin et al. [6] studied the preparation conditions of nan
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