Surface engineering on cholesteric cellulose nanocrystals films inducing emulsification, organic pollutants detection and separation

Abstract

Nowadays, organic pollutants have been major concerns in many fields. Production of functional materials based on renewable and sustainable resources for organic pollutants detection and removal was of much interest. Herein, multi-functional nanocomposite films based on cellulose nanocrystals (CNCs) with high optical haze, organic pollutant detection and emulsion separation capabilities, have been successfully fabricated based on hydrophobically-modified CNCs suspensions by 2-dodecen-1-succinic anhydride (DDSA) followed by radical polymerization with tridecafluorooctyl (TFMA). The suspensions displayed satisfying oil-in-water emulsion stabilization capabilities and the vacuum-dried films showed birefringence, high transparency, and optical haze (~85 %), due to the ordered arrangements of cellulose nanocrystals. The organic pollutant can be detected through the iridescent colors disappearing by Polarizing Optical Microscope observation. In addition of improved mechanical strength for application (27 MPa) and high contact angle of 131.6°, the hydrophobic films performed as high separation efficiency as >90 % of emulsion, due to the successfully grafting of hydrophobic molecules on the surface of CNCs. Thus, the surface modification for CNCs provide a facile approach of emulsification, pollutants detection and separation properties, which would widen the application potentials of renewable cellulosic resources in fields of environmental protection, engineering control and petroleum industry.

Keywords: Cellulose nanocrystals; Chiral nematic structure; Emulsion separation; Hydrophobicity; Organic pollutants detection; Surface modification.