LINE TENSION OF A SESSILE DROP ON A FLUID FLUID INTERFACE MODIFIED BY A PHOSPHOLIPID MONOLAYER

The line tension of the three-phase contact zone of a sessile drop was determined experimentally. Droplets of dibutyl phthalate ranging in maximum diameter from 13 to 400 mu m were placed on a monolayer of dipalmitoyl phosphatidylcholine spread at a fluorocarbon (FC43)-saline interface. The contact radii and contact angles and a linearized form of the modified Young equation were used to calculate the line tension values at five FC43-saline interfacial tensions. The line tensions found varied from 1. 0 to 2. 4 multiplied by 10** minus **8 J/m. It was not possible to determine from our data if any dependence on contact angle or interfacial tensions exists.