The line tension values of n-octane and 1-octene on a hexadecyltrichlorosilane coated silicon wafer, are determined by contact angle measurements at temperatures near a first-order wetting transition $T_w.$ It is shown experimentally that the line tension changes sign as the temperature increases toward $T_w$ in agreement with a number of theoretical predictions. A simple phenomenological model possessing a repulsive barrier at $l_0=5.1\mathrm{}\pm 0.2\mathrm{nm}$ and a scale factor of $B=78\mathrm{}\pm 6$ provides a quantitative description of the experiments.

• Received 2 June 2000

DOI:https://doi.org/10.1103/PhysRevE.63.031601