Modification of surface wetting properties of a substrate

A method of modifying the anisotropic wetting properties of the surface of a polymer substrate, the method comprising the steps of:

• (A) applying a first mold having an imprint forming surface including patterns to said polymer substrate at a first temperature to form a first imprint on said polymer substrate;
• (B) applying a second mold having an imprint forming surface including patterns having a smaller dimension than the patterns of said first mold to said first imprint at a second temperature that is different to said first temperature to form a second imprint that is in the same polymer substrate as the first imprint, said second mold configured to vary the size of said first imprint along the height of said first imprint when forming a second imprint on said first imprint which comprises a hierarchical structure;
• and
• (C) orienting, during said applying step (B), said second mold relative to said first imprint to form said hierarchical structure on said polymer substrate for modifying the wetting properties of the polymer substrate surface.