Cellulose Photonic Crystal For The Detection Of Harmful Gas

We developed a simple,ecomonical and efficient method to construct 3D and 2D opal and inverse opal cellulose photonic crystal film?CPCF?sensors by embedding 3D or 2D polymethyl methacrylate?PMMA?colloidal arrays into cellucarboxymethyl cellulose?CMC?and methyl cellulose?MC?,respectively.The morphology and optical properties of CPCFs were characterized with SEM,diffraction spectra,Debye rings and structural color.The results showed that both o fperiodic 3D and 2D arrays were highly ordered,and the obtained CPCFs werevisible to the eye in the entire visible spectrum,and their brilliant color can be controlled by varying the particle diameters or the lattice spacing.For the 3D CPCFs,the stopbands of the inverse opal CPCFs had a 220 nm blue-shifts compared with that of the PMMA opal.To the contrary,the particle spacing of 2D inverse opal CPCFs was increased about 100 nm,along with a 2.1 cm decrease of the Debye ring.By been exposed to acetone,benzene,toluene,dimethylbenzene,and formaldehyde gas,the 3D opal CPCFs displayed a quickly sensing performance with irreversible color changes from iridescent to white attribute to dissolved colloidal arrays.However,when opal CPCFs were exposed in different concentrations of NH_3,the lattice constant changed with the swelling PMMA particles,and eventually the diffraction wavelength red shifted about 12 nm when the concentraction of NH₃ reached up to 2100 ppm.The high stability,visual detection r esults,low requiremntes of detection conditions and environmental friendliness promised a new opportunity for the optical switching and sensing application.