Barrier Diamond-like Carbon Coatings on Polydimethylsiloxane Substrate

Area of Science:

• Materials Science
• Surface Chemistry
• Plasma Physics

Background:

• Polydimethylsiloxane (PDMS) modification via plasma treatment alters surface geometry, enabling wrinkle formation.
• Hydrophobic property recovery is a common issue after PDMS plasma modification.

Purpose of the Study:

• To investigate the stability of surface properties of PDMS after plasma treatment under various conditions.
• To evaluate the effectiveness of diamond-like carbon (DLC) coatings in maintaining hydrophobicity.

Main Methods:

• Plasma treatment of PDMS substrates using radio frequency plasma-assisted chemical vapor deposition (RF PACVD).
• Treatments were performed in argon, nitrogen, oxygen, and methane atmospheres with negative biases from 100 V to 500 V.
• Characterization of DLC coatings, including thickness and chemical structure (ID/IG ratio).

Main Results:

• Only DLC-coated PDMS surfaces exhibited stable contact angles for deionized water.
• DLC coating thickness ranged from 10 to 30 nm, with ID/IG ratios between 0.41 and 0.8.
• Plasma treatments with other gases resulted in a transition from hydrophilic to hydrophobic properties.

Conclusions:

• DLC coatings produced via RF PACVD on PDMS substrates demonstrate stable hydrophobic properties.
• DLC coatings act as effective barriers, preventing the typical hydrophobic recovery observed with other plasma treatments.
• The study highlights the potential of DLC coatings for applications requiring stable surface hydrophobicity on PDMS.