Similar to imprint nanolithography, capillary nanolithography employs a patterned elastomeric mold. However, instead of utilizing high pressure, when the temperature is raised above the Tg, capillary forces enable the polymer to fill the voids within the mold. Suh and Jon used molds made from  (PUA). These were placed on spin coated, water-soluble polymer, polyethylene glycol (PEG), which was raised above PEG's Tg. This study found that the addition of nanotopography increased the contact angle, and this increase was dependent on the height of the nanotopography.  Often, this technique produces a meniscus on the tip of the protruding nanostructures, characteristic of capillary action. The mold can later be dissolved away. Combinatorial lithography approaches are also used. One study used capillarity to fill PDMS molds with PUA, first partially curing the polymer resin with UV light. After microstructures were formed, pressure was applied to fabricate nanostructures, and UV curing was used again. This study is a good example of the use of hierarchical structures to increase surface hydrophobicity.