Insights into the Mass Transfer through Vapor-Liquid Interfaces from Molecular Dynamics Simulations | AIChE

Insights into the Mass Transfer through Vapor-Liquid Interfaces from Molecular Dynamics Simulations

Authors 

Stephan, S. - Presenter, Laboratory of Engineering Thermodynamics (LTD), TU Kaiserslautern
Here, poly(4,4′-oxydiphenylene-co-pyromellitimide) (polyimide, PI) film was treated with low-pressure plasmas gases such as hydrogen (H2), carbon tetrafluoride (CF4), carbon dioxide (CO2), oxygen (O2), and air to change the surface properties. The contact angle (CA, θ) value of the plain PI film measured as 64.5°±2.1 and increased to 117.2°±1.7 after the CF4 plasma treatment. Additionally, H2, CO2, O2, and air plasma-treated PI films became more hydrophilic with the CA values of 18.7°±1.1, 11.3°±0.8, 2.7°±0.5 and 11.6°±0.3, respectively. The surface free energy (SFE) of PI films were also changed to 12.7±1.4 mN/m, 75.3± 0.8 mN/m, 74.1±0.3 mN/m, 80.8±0.4 mN/m, and 73.2±0.6 mN/m from 49.7±1.7 mN/m after CF4, H2, CO2, O2, and air plasma treatments. Furthermore, the surface of the PI film was exposed to successive plasmas of CF4 and O2, O2 and CF4, CF4 and CO2, CO­2, and CF4 multiple times for several times. Upon multiple treatments the CA value was increased as high as 120.3°±0.4 and the SFE value was decreased as low as 10.3±1.2 mN/m. The stability tests of the surface-modified PI tested in an ambient environment were found intact and unchanged even after 20 days of aging.