Duty cycle dependent chemical structure and wettability of RF pulsed plasma copolymers of acrylic acid and octafluorocyclobutane

• Published in: Applied surface science 2018-04, Vol.436, p.411-418
• Main Authors: Muzammil, I., Li, Y.P., Li, X.Y., Lei, M.K.
• Format: Article
• Language: English
• Subjects: Plasma copolymerization; RF pulsed plasma; Superhydrophilicity; Superhydrophobicity; Surface adhesion; Tunable wettability
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2017.11.261

[Display omitted] •C4F8-co-AA polymers were deposited using pulsed wave RF plasma polymerization.•Plasma pulsation regulates the chemical structure and surface wettability.•Emergence of hydrophilic contents leads to surface heterogeneity causing water adhesion.•Tunable water adhesiveness from repulsive to adhesive superhydrophobicity was demonstrated.•Controllable wettability was confirmed from superhydrophobicity to superhydrophilicity. Octafluorocyclobutane and acrylic acid (C4F8-co-AA) plasma copolymer coatings are deposited using a pulsed wave (PW) radio frequency (RF) plasma on low density polyethylene (LDPE). The influence of duty cycle in pulsed process with the monomer feed rate on the surface chemistry and wettability of C4F8-co-AA plasma polymer coatings is studied. The concentration of the carboxylic acid (hydrophilic) groups increase, and that of fluorocarbon (hydrophobic) groups decrease by lowering the duty cycle. The combined effect of surface chemistry and surface morphology of the RF pulsed plasma copolymer coatings causes tunable surface wettability and surface adhesion. The gradual emergence of hydrophilic contents leads to surface heterogeneity by lowering duty cycle causing an increased surface adhesion in hydrophobic coatings. The C4F8-co-AA plasma polymer coatings on the nanotextured surfaces are tuned from repulsive superhydrophobicity to adhesive superhydrophobicity, and further to superhydrophilicity by adjusting the duty cycles with the monomer feed rates.