If , then

And since the component could never be positive, will always be negative.

Negative interfacial tension implies that there will be a spontaneous increase in the area in order to minimize the energy. In case of gels, this leads to swelling.

3. Apolar or weakly polar surfaces in water

If

This is strongly negative because AB interactions are much larger compared to LW interactions. This strong interaction is termed as hydrophobic attraction (force) and this could be a long range force.