Metastable Network Phases from Controlled Self-Assembly of High-χ Block Copolymers for Biomimetic Materials*

Well-ordered nanonetwork materials are appealing and promising for innovative properties such as optical and mechanical metamaterials as inspired by nature (photonic property from wing structure of butterfly and high impact property from dactyl club of mantis shrimp). Here, this work aims to suggest a facile method for acquiring network phases from self-assembly. By taking advantage of controlled self-assembly for high-χ polystyrene-block-polydimethylsiloxane block copolymers (BCPs), it is feasible to acquire metastable network phases from the use of selective solvent for self-assembly under controlled evaporation of the solvent. A variety of kinetically trapped network phases with high degree of ordering can be obtained from a single-composition lamellar phase, giving an easy method to acquire network phases even with large packing frustration (entropic penalty). Furthermore, the windows for the formation of metastable network phases can be even expanded through controlled self-assembly of star-block BCPs as compared to diblocks. The easy fabrication of network phases from the bottom-up approach gives rise to the feasibility for biomimicking the outstanding properties of butterfly wing structure and mantis shrimp dactyl club.