Polymer-immobilized 2D nonclose-packed colloidal crystals

Abstract We present a novel methodology for immobilizing 2D nonclose-packed colloidal crystals in polymer resins. In our previous work (Aoyama Y, Toyotama A, Okuzono T, Yamanaka J. Two-Dimensional Nonclose-Packed Colloidal Crystals by the Electrostatic Adsorption of Three-Dimensional Charged Colloidal Crystals. 2019. Langmuir 35, 9194.), we detailed a fabrication technique involving electrostatic adsorption of 3D charged colloidal crystals onto a glass substrate with an opposite charge. Drying is essential for producing durable materials as these structures are formed in an aqueous environment. However, merely drying the crystals can lead to considerable disruption of the particle arrangement because of the capillary forces that arise between the particles during water evaporation. In this study, we demonstrate the immobilization of 2D colloidal silica crystals in a polymer resin. First, we introduced a water-soluble polymer, poly(dimethyl acrylamide), which effectively adsorbs both the particles and the substrate to stabilize the crystals, followed by the evaporation of water. Various configurations of 2D colloidal silica crystals were successfully fixed onto the glass substrates. After immobilization with poly(dimethyl acrylamide), the dimethyl acrylamide monomer was added and underwent polymerization, resulting in a more robust entrapment of the colloidal crystals in the polymer resin. This method can be applied to other polymers and hydrophobic particles. The current findings are expected to be valuable for a broad range of photonic applications.