Coassembling Hydroxypropyl Cellulose into a Chiral Nematic Composite and Patternization with a Photomask and Direct Ink Writing

Additive manufacturing (AM) is a next-generation technique for engineering hierarchically structured materials. The development of sustainable ink materials for AM is imperative. In this work, we explored hydroxypropyl cellulose (HPC) as a sustainable photonic ink for patterning by photomask and direct ink writing techniques. Specifically, we comprehensively investigated the coassembly behavior of HPC with a guest monomer into a chiral nematic structure and the parameters that affect the transition from a solution to composite film of HPC/monomer. The results reveal that the HPC/monomer has the ability to form a chiral nematic structure, and such a hierarchical structure can reflect light with a specific wavelength. The helical pitch in the chiral nematic structure, corresponding to the reflected wavelength, can be modulated via HPC concentration, the addition amount of monomer, cross-linking time, and drying temperature. Additionally, the composite exhibits robust mechanical properties and is capable of tolerating a wet environment (both high relative humidity and water). This comprehensive study is a fascinating example of using a sustainable cellulose derivative as a 3D printing ink and provides powerful support for the development of structural color materials.