Rapid, Large-Area Synthesis of Hierarchical Nanoporous Silica Hybrid Films on Flexible Substrates.

We report a simple strategy for the creation of large-area nanoporous hybrid films of silica, carbon, and gold on polyethylene terephthalate via photothermal processing. This method enables the selective heating of light-absorbing thin films on low-temperature substrates using submillisecond light pulses generated by a xenon flash lamp. The film contains gold nanoparticles as the nano-heaters to convert light energy into heat, a sacrificial block copolymer surfactant to generate mesopores, and cross-linked polyhedral oligomeric silsesquioxane (POSS) as the silica source to form the skeleton of the porous structure. Hierarchical porous structures are achieved in the films after photothermal treatment with uniform mesopores (44~48 nm) on the surface and interconnected macropores (>50 nm) underneath resulting from a foaming effect during release gaseous decomposition products. The loading of gold nanoparticles is up to 43 wt % in the product with less than 2 wt % organic residue. This rapid and large-area synthetic process of porous structures is compatible with roll-to-roll manufacturing for the fabrication of flexible devices.