Ice-Templated Materials: Sophisticated Structures Exhibiting Enhanced Functionalities Obtained after Unidirectional Freezing and Ice-Segregation-Induced Self-Assembly

This review aims to demonstrate the capability of the ice-segregation-induced self-assembly (ISISA) process for the preparation of materials with highly sophisticated structures (e.g., hierarchical materials exhibiting organization at different scale levels). Cryogenic processes (consisting of the freezing, storage in the frozen state for a definite time, and defrosting of low - or high-molecular-weight precursors, as well as colloid systems, as either a water solution or suspension, or forming a hydrogel) have been widely used for the scaffolds preparation. However, the recent success in the control of the morphology (e.g., by unidirectional freezing in nitrogen liquid) and the possibility to extend the compositional nature of the resulting materials has recently attracted much attention to the ISISA process. Besides, this review aims to exemplify how the aqueous nature of the ISISA process allows for the in-situ incorporation of biological entities which provides not only hierarchy but also functionality to the resulting materials. The combination of hierarchy and functionality is characteristic of biological structures and must make these "smart" materials highly suitable in biotechnology and biomedicine. Thus, interesting examples of biocatalytic materials (for organic synthesis and fuel cell technologies) and biosensors, and scaffolds exhibiting enhanced functional (in terms of both biocompatibility and biodegradability) and mechanical performance, are reviewed in this work.