Effect of surface wettability on the antibacterial activity of nanocellulose-based material with quaternary ammonium groups

Cellulose nanocrystals (CNCs) is a kind of natural, renewable, and biocompatible materials that can be functional via the surface modification. A covalently bonded CNCs-g-PDMAEMA was prepared by grafting 2-(dimethylamino) ethyl methacrylate (DMAEMA) on the CNCs' surface via atom transfer radical polymerization (ATRP). Subsequently, the tertiary amino groups of the CNCs-g-PDMAEMA were transferred to quaternary ammonium groups by adding alkyl bromides with different carbon chain lengths (C10-C18). It was found that the antibacterial activity of the prepared materials is related to the quaternary group structure. The material containing C10 alkyl in quaternary group exhibited the best antibacterial efficiency, which was closely associated with the wettability of the quaternary CNCs-based polymers. The lower wettability of materials with higher hydrophobicity may impose a restriction on the polymeric antibacterial groups' accessibility to the cytoplasmic membrane of bacteria. The antimicrobial CNCs-based composites may be potential to apply as coating agents for aseptic packaging.