Structural Colors Derived from the Combination of Core–Shell Particles with Cellulose

Abstract

Combining cellulose-based components with functional materials is highlyinteresting in various research fields due to the improved strength and stiffnessof the materials combined with their low weight. Herein, the mechanical propertiesof opal films are improved by incorporating cellulose fibers and microcrystallinecellulose. This is evidenced by the increase in tensile strength of 162.8% afteradding 10 wt% of microcrystalline cellulose. For this purpose, core–shell particleswith a rigid, crosslinked polystyrene core and a soft shell of poly(ethyl acrylate) andpoly(ethyl acrylate-co-hydroxyethyl methacrylate) are synthesized via starved-feedemulsion polymerization. The synthesized particles’ well-defined shape, mor-phology, and thermal properties are analyzed using transmission electronmicroscopy, scanning electron microscopy, and differential scanning calorimetrymeasurements. Free-standing mechanochromic opal films with incorporatedcellulose and structural colors are obtained after processing the core–shell particleswith cellulose via extrusion and the melt-shear organization technique. Thehomogeneous distribution of the cellulose within the composite material isinvestigated using fluorescent-labeled cellulose. The opal film’s angle-dependentstructural color is demonstrated using reflection spectroscopy.