Cellulose-based photo-curable chiral nematic ink for direct-ink-writing 3D printing.

3D printing technology is one of the most promising strategies for constructing topological functional materials. The development of functional inks is a core issue in the technical development of 3D printing technology. In this study, we engineered photonic crystal inks based on chiral nematic liquid crystals of cellulose derivative, i.e. hydroxypropyl cellulose (HPC), and applied it to direct-ink-writing (DIW) 3D printing technology. We modified hydroxypropyl cellulose by etherification reaction to obtain photo-cross-linkable water-soluble hydroxypropyl cellulose acrylate (HPCA) with different degrees of substitution (DS). We comprehensively explored the effect of the DS on the initial concentration of formed chiral nematic liquid crystal and quantitatively, analyzed the relationship between the DS and the helical structure of the chiral nematic structure. We used photo cross-linkable chiral nematic HPCA as photonic crystal ink to construct structure-color 3D objects of diverse shapes. The constructed structure-color objects showcase robust tolerance against temperature and acidic conditions (pH = 1). Moreover, the color of the constructed objects is independent of the observation angle. The photonic crystal ink based on chiral nematic liquid crystals of biodegradable polysaccharide materials is expected to have excellent market prospects in the fields of such as smart packaging and optical devices.