Bio-Inspired Silica Films Combining Block Copolymers Self-Assembly and Soft Chemistry: Paving the Way toward Artificial Exosqueleton of Seawater Diatoms.

This review is in line with the principles of bio-inspiration and biomimicry in order to envisage a softer and more environmentally friendly chemistry. Here, the source of inspiration is a microalga from the oceans with the ability to build an exoskeleton of silica under ambient conditions. Following this model, this review is interested in different ways of creating porous silica films with a hierarchical porosity similar to diatoms. For this purpose, polymeric/hybrid/inorganic films structured in honeycomb using the breath figure method are reported. This versatile and easy to implement method based on the principle of rapid evaporation of a solvent in a humid atmosphere is widely used in the formation of structured films with micron-sized pores. In addition to this, the self-assembly of copolymer at the nanoscale can be addressed to obtain a hierarchically structured film. Following this structuration step, the degradation of a sacrificial block is then described from the most energy-intensive to soft process, allowing an added nanoporosity to the micron porosity of the BF method. Finally, hierarchical porous silica films are described using the sol-gel process, which is known as a soft chemistry process.