Mechanical, electrical and optical properties of cellulose nanofiber films modified using polydopamine coating

Abstract

Cellulose, a natural fiber, has been employed vastly for structural components due to its high mechanical strength and young’s modulus. The hydrophilic hydroxyl groups on the surface of cellulose nanofiber enables formation of cellulose-based nanocomposites with high mechanical properties which has been widely studied. The interfacial bonding of the composites between cellulose and other polymers could be improved further by surface modification of cellulose. Aiming to improve the mechanical properties of cellulose nanofiber and its composites as well as functional properties, a bio-inspired approach to coating polydopamine onto cellulose nanofiber was developed. Due to strong adhesion ability and self-polymerization of dopamine in tris buffer, polydopamine could be easily coated on cellulose nanofiber under mild conditions. Prefabricated cellulose nanofiber film and filament were modified by coating with polydopamine. FTIR, XPS, SEM confirmed a homogeneous polydopamine coating on cellulose nanofiber film and filament. The mechanical strength and stiffness of the cellulose-polydopamine fiber and the respective composite materials were investigated. The photostability, antibacterial, and electrical properties of the polydopamine-cellulose nanofiber were also studied.