Multicomponent chiral hydrogel fibers with block configurations based on the chiral liquid crystals of cellulose nanocrystals and M13 bacteriophages

Anisotropic hydrogel fibers consisting of distinct blocks with heterogeneous internal structures and chemical components are expected to have many advanced functionalities. Based on the chiral liquid crystals (CLCs) of rod-like cellulose nanocrystals (CNCs) and M13 bacteriophages (M13), the current work reports a versatile method to prepare hydrogel fibers with block configurations that have chiral internal structures and multiple components. The effects of confinement on the CLC phases and blockwise photopolymerization were simultaneously explored to address the challenges of how to maintain the delicate chiral ordering of the biological nanorods during gelation and how to seamlessly fuse together the hydrogel blocks containing the CLC phases of different nanorods. The hydrogel precursors containing the CLC phases of either CNCs or M13 were confined in cylindrical glass capillaries and sequentially photopolymerized into hydrogels. Chiral hydrogel fibers with di- or tri-block configurations were prepared, in which hydrogel blocks containing the CLC phases of either CNCs or M13 fuse together seamlessly and arrange alternatively. Due to the unique physiochemical properties specific to CNCs and M13, each hydrogel block has different properties, including chiral fingerprints with various pitches, swelling/deswelling behaviors, mechanical strength, stretchability, strain-sensitive birefringent colors, etc. The synergic effects of these properties endow the CNC–M13 chiral hydrogel fibers with block dependent swelling/deswelling, asymmetric strain deformation and stretchability, which can be tuned by surface chemical modifications specific to the biological rods. These block chiral hydrogel fibers might have applications in multi-task strain sensing, actuations, soft chiral optics, etc.