Linear Birefringent Films of Cellulose Nanocrystals Produced by Dip-Coating

• Main Authors: Arturo Mendoza-Galván, Tania Tejeda-Galán, Amos B. Domínguez-Gómez, Reina Araceli Mauricio-Sánchez, Kenneth Järrendahl, Hans Arwin
• Format: Article
• Language: English
• Published: MDPI AG 2018-12-01
• Series: Nanomaterials
• Subjects: nanostructured films; birefringence; nanocrystalline cellulose; Mueller matrix
• Online Access: http://www.mdpi.com/2079-4991/9/1/45
• ISSN: 2079-4991

Transparent films of cellulose nanocrystals (CNC) are prepared by dip-coating on glass substrates from aqueous suspensions of hydrolyzed filter paper. Dragging forces acting during films’ deposition promote a preferential alignment of the rod-shaped CNC. Films that are 2.8 and 6.0 µm in thickness show retardance effects, as evidenced by placing them between a linearly polarized light source and a linear polarizer sheet in the extinction configuration. Transmission Mueller matrix spectroscopic ellipsometry measurements at normal incidence as a function of sample rotation were used to characterize polarization properties. A differential decomposition of the Mueller matrix reveals linear birefringence as the unique polarization parameter. These results show a promising way for obtaining CNC birefringent films by a simple and controllable method.