Hyperthermal Atomic Oxygen and Argon Modification of Polymer Surfaces Investigated by Molecular Dynamics Simulations

Abstract

The deposition of reactive and unreactive particles on polymer surfaces at hyperthermal incident energies is investigated using classical molecular dynamics simulations. The forces are calculated with the second‐generation reactive empirical bond‐order potential with modified parameters for C,H,O interactions. Three prototypical polymers, polyethylene (PE), polypropylene (PP) and polystyrene (PS), are modified by atomic oxygen and argon that are deposited with kinetic energies of 25, 50 and 100 eV. The non‐reactive argon is predicted to primarily break carbon–carbon bonds and remove hydrogen as a secondary process, while the reactive oxygen is more efficient at removing hydrogen during new bond formation with the polymer. The PE and PP are found to have similar responses to hyperthermal argon and oxygen deposition, while PS is found to be the most susceptible to oxygen modification.

Low-energy irradiation effects in cellulose

“…2) are considerably bigger than the bond energies for C-C and C-O bonds in cellulose ($3 À 4 eV for REBO potential 14 ). Similar effect can be seen in other materials, such as Si: E bond ¼ 2.3 eV and E thresh ¼ 13 eV, 16 and Fe: E bond ¼ 1.1 eV and E thresh ¼ 16 À 20 eV.…”

Primary Radiation Defect Production in Polyethylene and Cellulose

“…For cellulose simulations involving oxygen, we used the REBO potential for C, H, and O interactions by Ni et al 23 that was recently improved and updated by Kemper and Sinnott. 24 These simulations were carried out using a MD code written by Travis Kemper, the same code that was used in ref 24. Often irradiation of materials is simulated as a bombardment by a high-energy particle, like argon or deuteron, into the surface of the specimen. For example in the work of Beardmore et al 14 HDPE was bombarded by argon atoms with an energy of 1 keV.…”

“…For cellulose simulations involving oxygen, we used the REBO potential for C, H, and O interactions by Ni et al that was recently improved and updated by Kemper and Sinnott . These simulations were carried out using a MD code written by Travis Kemper, the same code that was used in ref .…”

Charge Transfer Potentials

“…The reactive term in the name indicates that this potential has the capacity to model bond breaking and bond formation. The second-generation REBO potential (REBO2) 15 provided even more accurate descriptions of short-range bonding in solid state carbon materials and hydrocarbon systems, and was subsequently further extended to C-H-O, [16][17][18] C-H-F, 19 and C-H-S 20 systems. Most recently, Liang et al 21 parameterized REBO2 to model the metallic, ionic and covalent bonding present in Mo-S systems.…”