Christiansen Effect-Based Physical Coloration of a Cellulosic Monolith Conveniently Fabricated Using Thermally Induced Phase Separation

摘要

A cellulose acetate (CA) polymer monolith is conveniently fabricated using the thermally induced phase separation method. When a CA monolith in sheet form is immersed in a non-solvent mixture with a suitable refractive index, transparent coloration due to the Christiansen effect is observed. This colorization is arbitrarily controlled by temperature and the non-solvent composition. The wavelength of maximum transmission of the immersed monolith spectrum increases-with high sensitivity-at high temperatures and in non-solvent with a low refractive index, while being independent of the monolith morphology. Following the alkali hydrolysis of the CA monolith, the transmission spectrum of regenerated cellulose monolith immersed in mixed non-solvent clearly shifts by the Christiansen effect, whereas natural cellulose fibrils (wood cellulose and bacterial cellulose) with high crystallinity in the same non-solvent are opaque or shows no Christiansen effect, respectively. The results indicate the potential of the amorphous cellulose monolith for use as a chemosensor.