Shear-Coated Linear Birefringent and Chiral Cellulose Nanocrystal Films Prepared from Non-Sonicated Suspensions with Different Storage Time

Nanomaterials

Olga Rubi Juárez-Rivera¹  Reina Araceli Mauricio-Sánchez¹  Arturo Mendoza-Galván¹  Hans Arwin²  Kenneth Järrendahl² 

[1] Cinvestav-Unidad Querétaro, Libramiento Norponiente 2000, Querétaro 76230, Mexico;Materials Optics, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden;

关键词: cellulose nanocrystals;    structural color;    linear birefringence;    circular dichroism;    Mueller matrix;   

DOI  :  10.3390/nano11092239

来源: DOAJ

【 摘 要 】

Nanocelluloses are very attractive materials for creating structured films with unique optical properties using different preparation techniques. Evaporation-induced self-assembly of cellulose nanocrystals (CNC) aqueous suspensions produces iridescent films with selective circular Bragg reflection. Blade coating of sonicated CNC suspensions leads to birefringent CNC films. In this work, fabrication of both birefringent and chiral films from non-sonicated CNC suspensions using a shear-coating method is studied. Polarization optical microscopy and steady-state viscosity profiles show that non-sonicated CNC suspensions (concentration of 6.5 wt%) evolve with storage time from a gel-like shear-thinning fluid to a mixture of isotropic and chiral nematic liquid crystalline phases. Shear-coated films prepared from non-sonicated fresh CNC suspensions are birefringent, whereas films prepared from suspensions stored several weeks show reflection of left-handed polarized light. Quantification of linear and circular birefringence as well circular dichroism in the films is achieved by using a Mueller matrix formalism.

【 授权许可】

Unknown