Mechano-Optical Octave-Tunable Elastic Colloidal Crystals Made from Core−Shell Polymer Beads with Self-Assembly Techniques

Abstract

Elastic colloidal crystals, even without a full photonic band gap, hold promise for fascinating applications and for easy large-scale fabrication by self-assembly. However, high mechanical robustness is required for optical, decorative, or security applications, such as tunable optical modulators/filters or optical tension indicators. Here, we present brilliantly colored filled-pore colloidal crystals that withstand elongation by 100%, i.e., one optical octave. We employ a variety of vertical deposition techniques to self-assemble monodisperse core-shell polymer beads with a film-forming shell and flexible core. We find a good theoretical description of crystal thickness for all techniques. The crystals have centimeter-sized macroscopic order, and their orientation is fully controlled by the substrate plane and meniscus line.

Tunable Colors in Opals and Inverse Opal Photonic Crystals

“…[ 111 ] The core/shell particles were prepared by two-step or multi-step emulsion polymerization either with hard cores or with fl exible cores and fi lmforming soft shells. Softer cores provided more fl exible fi lms but compromised the refractive index contrast.…”

Artificial Opals as Nanophotonic Materials for Optical Communication

“…For self-assembly the polymer dispersions were diluted as is, without any purification step. We grow the photonic crystal in near-vertical deposition without any mechanical movement in order to fabricate large-volume thick crystals [5,6]. The contraction of the crystal in the latest stages of drying induces mechanical stress that ultimately leads to adhesive failure at the polymer-substrate interface.…”

Mechanoresponsive Color Change in Cholesteric Liquid Crystal Film

“…Attempts have been made to create these materials by polymer chains covalently bonded with mechanophores [1,2], polymers blended with chromophores [3], colloidal crystal assemblies [4][5][6], or polymeric hydrogels containing self-assembled polymeric surfactants [7]. The colloidal crystal and surfactant bilayer assemblies, have periodic structures, which can generate iridescent colors of structural origin based on the Bragg diffraction.…”