Hydrogels Derived from Cellulose Nanocrystals

In quest for new functional materials, cellulose nanocrystals (CNCs) have attracted great interest due to the ir sustainability, biocompatibility, ease of surface functionalization, and mechanical strength. In this thesis different hydrogels derived from CNCs for various applications have been developed. The hydrogels derived from CNC in this thesis can be divided into isotropic and anisotropic hydrogels. High capacity, low cost and sustainable materials for waste water treatment and heavy metal removal are in high demand. An isotropic nanocolloidal hydrogel based on CNCs and GQDs was developed. The microstructure , permeability and mechanical properties of the hydrogel was dependent on the concentration and the ratio of the two precursors. Microfluidic microgels have been used for heavy metal scavenging and wastewater treatment applications. Higher concentration of GQDs lead to higher adsorption capacity for different heavy metal ions. To study the possibility of alignment of CNCs in shear field, studying the kinetic of alignment and relaxation of alignment, an oscillatory microfluidic device was used. Higher freque ncy of oscillations led to higher alignments . An increase in the viscosity of the CNC suspension led to higher degree of alignment. At higher viscosities the relaxation of alignment was also slower. The morphology of the native tissue contains unidirectionally aligned collagen fibers, anisotropic hydrogels t hat mimic the native tissu e morphology are highly desired . Nanofibrillar hydrogel derived from CNCs and gelatin have been prepared to study the role of shear in fabrication of anisotropic hydrogels. Variation of concentration and ratio of hydrogel precursors led to various gelation times, permeability and mechanical properties. Compositionally gradient sheets were fabricated. Finally, v ariation in the sub strate temperature was explored to tune the degree of alignment in the hydrogel sheets. Hydrogels derived from CNC and Chitosan were developed to form a shear -thinning photo crosslinkable hydrogel for fabrication of personalized wound dressings. The structure, mechanical properties and swelling of the hydr ogels were dependent on the concentration and ratio of the precursors. The hydrogels could be loaded with various active ingredients (AI) to add different functionalities. These functional hydrogels were printed in different shapes to program the release of AI in a controlled manner.