Surface functionalization of polypropylene nanoparticles in a pulsed low pressure air plasma discharge

• Published in: Surface science 2022-03, Vol.717, p.121987, Article 121987
• Main Authors: Rayatnia, M., Foroutan, G.
• Format: Article
• Language: English
• Subjects: Air plasma; Carbonyls; Fluxes; Functional groups; Gas pressure; Gas temperature; Low pressure; Multi-fluid Simulations; Nanoparticles; Periodic variations; Plasma Discharges; Plasma jets; Polymer Surface Treatment; Polypropylene; Positive ions; Pressure effects; Propylene Nanoparticles; Radicals
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2021.121987

•Surface functionalization of polypropylene nanoparticles is simulated in a repetitively pulsed air plasma discharge.•The numerical model includes plasma fluid equations, chemistry model, and surface deposition model.•The surface coverages of all functional groups are continuously increased with the pulse number.•With increase in gas pressure, the fluxes of radicals and the surface coverages are increased but they are reduced by increase in gas temperature. [Display omitted] One dimensional multi-fluid model is combined with a surface model to study the functionalization of polypropylene nanoparticles immersed in a repetitively pulsed low pressure air plasma. It is found that, the number densities of the charged and metastable species show periodic variations with time, whereas the concentrations of radicals increase in successive pulses. O2+ is the most important positive ion and O, OH, O3, and HO2 are the most important radicals in the functionalization of the polypropylene nanoparticle. The surface coverages of all functional groups are increased with increase in the pulse number, while the coverage of alkyl sites decreases after 200 pulses. At high pressures, the most important functional group with highest surface coverage is peroxy, followed by carbonyl, alcohol, alkoxy, and hydroperoxy. The electron number density and the incident fluxes of O2+ ions and O, OH, O3, and HO2 radicals, as well as the surface coverages of all functional groups are increased with increase in the gas pressure. Completely reverse effects were observed with increase in the gas temperature such that the incident ion and radical fluxes and all surface coverages decrease with increase in the gas temperature.