THE MEASUREMENT OF SURFACE-ENERGY BY VIDEO ANALYSIS OF CAPTIVE-BUBBLECONTACT-ANGLES

Surface energy has been demonstrated to have a significant effect upon the settlement and growth of many marine organisms. However, the meas urement of surface energy has either been too expensive for most marin e laboratories to consider its use, or the methods used have relied up on classical contact-angle theory. Modern contact-angle theory and a v ideo-based technique using captive bubbles are described. The techniqu e is non-destructive, inexpensive, rapid and accurate enough to compar e living and man-made surfaces. A precision of similar to 5 degrees ha s been achieved and rapidly-changing angles can be quantified. Data fo r PTFE sheet, Parafilm, acetate sheet, Geltek gel, sea-water-condition ed slate, Porphyra umbilicalis (L.) Agardh, Ciona intestinalis (L.), a nd Cyanea capillata (L.) are presented. The contact angles for the liv ing surfaces are smaller (31-44 degrees) than for all the non-living s urfaces (73-112 degrees), suggesting overall higher surface energies f or the biological materials studied.