Details

Autor(en) / Beteiligte

• Janocha, B
• Bauser, H
• Oehr, C
• Brunner, H
• Göpel, W

Titel

Competitive Electrowetting of Polymer Surfaces by Water and Decane

Ist Teil von

• Langmuir, 2000-04, Vol.16 (7), p.3349-3354

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2000

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The present study deals with electrocapillarity effects in the three-phase system water−decane−polymer. This system consists of a decane droplet which adheres under water on a polymer surface. We applied an electric potential between an electrode beneath the polymer film and a platinum electrode immersed in the water. The polymer film acts as insulator:  no steady electrical current flows between the electrodes. When the voltage is increased, the contact angle of decane and water changes, in some cases by up to 100°. The shape of the electrowetting curve (contact-angle cosine versus voltage plot) strongly depends on the type of the polymer. A saturation at higher voltages, connected with a hysteresis, is interpreted in terms of charge carrier injection into the polymer surface. Other deviations of the experimental results from the Lippmann−Young parabola concern a broadening with the polyolefins, a strong shift, and apparent reduction to one branch with two fluoropolymers, and for PET and a heavily oxidized PE sample the deviations concern a nearly zero dependence of the voltage.