Nanoporous polystyrene prepared via the selective removal of the low Mw component in polystyrene blends

Herein, we report a straightforward technique for the creation of nanoporous polystyrene (PS) films. By preparing PS blend samples with Mws of 600 000 and 600 g mol−1 followed by rinsing with n-heptane, the low Mw component was dissolved and removed to afford a low-density network of high Mw PS. Nanoscale pores are formed as a result of the miscibility and stability of the initial state. The resulting materials were characterized using ellipsometry, atomic force microscopy and scanning electron microscopy. Materials with an effective refractive index as low as 1.1 can be prepared using this approach. The effects of varying the size of the low Mw polymer and the application of low friction surfaces prepared with the nanoporous samples were investigated.