3D Printing of Multifunctional Chitosan-Based Hydrogels and Nanocomposites
Abstract
The ability to produce complex micro- or nano-structures in soft materials is significant for various applications such as tissue engineering, sensors, drug delivery and medical devices. In tissues or organs, surrounding micro-environments can affect cell alignment and organization that lead to the biological and functional complexity of native tissues. Naturally derived hydrogels are an important class of soft materials, which are exceptionally attractive for biomedical applications since they simulate the aqueous environment of extracellular matrices. However, precisely controlled architectures of naturally derived hydrogels are difficult to obtain through most conventional fabrication methods, and even with three-dimensional (3D) printing. Despite recent progress in the field of additive manufacturing, significant challenges persist to fabricate hydrogels with ordered structures and adequate mechanical and biological properties for mimicking native tissues. Besides, electronic waste and environmental pollution is a serious issue due to constant demand for newer and more powerful electronics. Many non-biodegradable polymers and toxic components are found in traditional electronics (such as capacitors and integrated circuits), and toxic solvents (such as isopropanol, acetone and trichloroethylene) are on occasion used in their fabrication. With the growing importance of sustainable development, it is of the upmost priority for companies in the electronic industry to develop and fabricate eco-friendly electronics. Natural polymer-based nanocomposites are excellent candidates for developing the next-generation of bio-sustainable electronics due to their lightweight, low-cost, and sustainable properties. Thus, in this work, we develop a 3D printing process to fabricate 3D microstructures of a natural polymer - namely chitosan (CS) - and its nanocomposites. This work proposes CS-based inks that can be fabricated by 3D printing at room temperature. The setup of 3D printing is composed of a computer-controlled translation stage and a three-axis positioning platform. The ink is loaded into a syringe, which can be extruded through a micronozzle. The ink filaments are deposited on the plate to form a structure in a layer-by-layer manner, where it undergoes filament solidification through solvent evaporation. We demonstrate a comprehensive characterization of the properties of CS inks for 3D printing at room temperature. The rheological properties of CS inks are analyzed by rotational rheometry at low to moderate shear rate and the process-related viscosity and flow behavior are characterized by capillary flow analysis, in order to formulate inks with shear thinning behavior for successful 3D printing. Solvent evaporation tests of different ink compositions are investigated by observing the weight reduction of extruded CS filaments with time. Since different structures fabricated by 3D printing require different processing parameters, a processing map is generated by considering parameters such as micronozzle diameter and ink concentration for the successful fabrication of one-dimensional (1D), two-dimensional (2D) and 3D CS structures. The results of X-ray diffraction (XRD) and tensile properties of CS filaments are also investigated, showing different material properties obtained after different processing steps. None
- Publication:
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Ph.D. Thesis
- Pub Date:
- 2018
- Bibcode:
- 2018PhDT.......104W
- Keywords:
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- Chemical engineering;Nanotechnology