Figure 12.

(a) Protein-based multilayer reflector of Loligo pealeii squid and the corresponding electrochemically tunable BCP lamellar structure using a voltage to create H⁺ in a PS-b-P2VP system that triggers large swelling of the P2VP domains. Inset a1) TEM cross section of a squid iridophore showing periodic layers, a2) electrically tunable BCP, a3) TEM of 1D lamellar BCP layer.¹⁷⁵ (b) Single gyroid chitin network and a model constant mean curvature surface clipped to a truncated octahedron shape and SEM images of a wing scale of Callophrys rubi butterfly. The network's single type of 3-coordinated vertices are at Wyckoff sites 8a in space group I4₁32 (no. 214 in ref.226) Reproduced with permission.²²⁵ Copyright 2011, American Physical Society (c) Schematic of hierarchical photonic structure of butterfly wing scales and their tunable reflectivity corresponding to uptake of vapor.