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Shahram Ajori

Shahram Ajori

Academic rank: Assistant Professor
ORCID:
Education: PhD.
ScopusId:
HIndex:
Faculty: 1
Address:
Phone: +98-41-37278900 #110

Research

Title
STACKING INTERACTIONS OF POLY PARA-PHENYLENE VINYLENE OLIGOMERS WITH GRAPHENE AND SINGLE-WALLED CARBON NANOTUBES: A MOLECULAR DYNAMICS APPROACH.
Type
Thesis
Keywords
MOLECULAR DYNAMICS
Year
2020
Researchers N. A. Dagadu(Student)، abu yaya(PrimaryAdvisor)، Shahram Ajori(PrimaryAdvisor)

Abstract

This work addresses the interactions between Poly (para-phenylene-vinylene) oligomers, PPV, graphene and single-walled carbon nanotubes using molecular dynamics simulation approach at 300 K. Binding energies of the PPV oligomers to graphene and single-walled carbon nanotubes, SWCNTs, were investigated. Calculations confirmed herringbone (HB) crystalline structure arrangement of oligo-PPV which is known to be the most stable conformation at 300 K. Interfacial interactions between crystal PPV, graphene and SWCNT were carried out. Molecular geometric optimisations performed with Universal Force Fields, UFF, were in good agreement with reported theoretical and experimental results. Hybrid Lennard-Jones parameters obtained through ab-initio and experimental parameterisation, B3LYP/6-31+G*/AMBER, gave the best results that matches with experiment and other theoretical calculations. Intramolecular energies of PPV chains were found to increase linearly, by approximately 50 kcal/mol, with each extending PPV monomer unit. The resulting binding energies between 3PPV-graphene and 3PPV-SWCNTs are comparable with existing calculations. For this work, it was found for; 3PPV-graphene ~-24 kcal/mol, 3PPV-(13,0) SWCNT ~ -22.5 kcal/mol, 3PPV-(8,8) SWCNT ~ -22 kcal/mol, and 3PPV-(6,6)SWCNT ~ -23 kcal/mol. Interfacial interactions properties analysis using radial distribution functions, RDF, for PPV-graphene and PPV-SWCNT, show significant disordering of molecules arrangement. This was much pronounced in PPV-SWCNT than in PPV-graphene. Finally, the radius of gyration, R_g, profiles show a net decrease of ~-0.8, for PPV-graphene with different surface coverage, and, a net increase of ~+0.6, for PPV-SWCNT; meaning, the binding between PPV-graphene is much stronger than with PPV-SWCNT.