The engineering of optical and acoustic material functionalities via construction of ordered local and global architectures on various length scales commensurate with and well below the characteristic length scales of photons and phonons in the material is an indispensable and powerful means to develop novel materials. In the current mature status of photonics, polymers hold a pivotal role in various application areas such as light‐emission, sensing, energy, and displays, with exclusive advantages despite their relatively low dielectric constants. Moreover, in the nascent field of phononics, polymers are expected to be a superior material platform due to the ability for readily fabricated complex polymer structures possessing a wide range of mechanical behaviors, complete phononic bandgaps, and resonant architectures. In this review, polymer‐centric photonic and phononic crystals and metamaterials are highlighted, and basic concepts, fabrication techniques, selected functional polymers, applications, and emerging ideas are introduced.

Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

Difluoroboron β-diketone complexes are versatile light-emitting molecules that exhibit tunable emission in both solution and the solid state. Among this class of dyes, difluoroboron dibenzoylmethane-polylactide (BF₂dbmPLA) polymers have been investigated for their molecular weight dependent fluorescence where the polymer chain plays an important role in BF₂dbm solid-state emission. Here the substituent effects were further examined with a lipid chain replacing polylactide. Surprising process dependent and reversible mechanochromic fluorescence was discovered for the boron dodecane complex (BF₂dbmOC₁₂H₂₅). A thermally annealed spin-cast film of the lipid dye on glass exhibited blue fluorescence under UV light but after shearing or scratching, the mechanically perturbed region turned yellow-green. The blue coloration could be rapidly recovered by thermal treatment of the film. The phenomena were investigated by steady-state fluorescence spectroscopy at room, low, and high temperatures, in situfluorescence microscopy, fluorescence lifetime measurements, and X-ray diffraction. Consistent with previous findings, the ordered-to-amorphous structural change that occurs upon mechanical perturbation may increase molecular rotational freedom, allowing for more efficient excimer emission, which typically occurs at longer wavelengths.