Cellulose nanocrystals (CNC) are well-suited to the preparation of biocomposite films and packaging material due to its abundance, renewability, biodegradability, and favorable film-forming capacity. In this study, different CNC and corn zein (CZ) composite films were prepared by adding CZ to the CNC suspension prior to drying, in order to change internal structure of resulting films. Films were developed to examine their performance as an alternative water vapor and oxygen-barrier for flexible packaging industry. Water vapor permeability (WVP) and oxygen transmission rate (OTR) of the biocomposite films decreased significantly in a specific ratio between CNC and CZ combined with 1,2,3,4-butane tetracarboxylic acid (BTCA), a nontoxic cross linker. In addition to the improved barrier properties, the incorporation of CZ benefitted the flexibility and thermal stability of the CNC/CZ composite films. The toughness increased by 358%, and Young’s modulus decreased by 32% compared with the pristine CNC film. The maximum degradation temperature increased by 26 °C, compared with that of CNC film. These results can be attributed to the incorporation of a hydrophobic protein into the matrix creating hydrophobic interactions among the biocomposite components. SEM and AFM analysis indicated that CZ could significantly affect the CNC arrangement, and the film surface topography, due to the mechanical bundling and physical adsorption effect of CZ to CNC. The presented results indicate that CNC/CZ biocomposite films may find applications in packaging, and in multi-functionalization materials.

Cellulose nanocrystals (CNCs) are composed of chiral cellulose units, which form chiral nematic liquid crystals in water that, upon drying, self-assemble to more complex spiral chiral sheets. This secondary structure arrangement is found to change with an external magnetic or electric field. Here, we show that one of the basic organization driving forces is electron spin, which is produced as the charge redistributes in the organization process of the chiral building blocks. It is important to stress that the electron spinexchange interactions supply the original driving force and not the magnetic field per se. The results present the first utilization of the chiral-induced spin selectivity (CISS) effect in sugars, enabling one to regulate the CNC bottom-up fabrication process. Control is demonstrated on the organization order of the CNC by utilizing different magnetization directions of the ferromagnetic surface. The produced spin is probed using a simple Hall device. The measured Hall resistance shows that the CNC sheets' arrangement is affected during the first four hours as long as the CNC is in its wet phase. On introducing the 1,2,3,4-butanetetracarboxylic acid cross-linker into the CNC sheet, the packing density of the CNC helical structure is enhanced, presenting an increase in the Hall resistance and the chiral state.