Free-Standing Polyimide Nanotips on Substrates for Preparation of Hollow TiO2 Nanotips

We report a facile method to fabricate free-standing polyimide (PI) nanotips on substrates by using plasma treatment with oxygen gas. The PI nanotips were prepared from the self-organization of unetchable materials deposited on a PI film during the plasma treatment. This approach provides a single-step process for the preparation of polymer nanotips in a large area (>inch scale). Furthermore, a selective patterning of the PI nanotips in a specific area was achieved by using a shadow mask. Due to excellent thermal resistance of PI, the PI nanotips maintained structural integrity at high temperature (similar to 300 degrees C). To demonstrate potential application of PI nanotips as a template for hollow nanostructures, hollow TiO2 nanotips were prepared after atomic layer deposition of TiO2 followed by the burning of PI layer.