Dissertation Defence: 3D-Printed Conductive Cellulose Cryogels for Electromagnetic Interference Shielding: Exploring Structural Design, Printability, and Shape Fidelity
October 10 at 10:00 am - 2:00 pm
Majed Amini, supervised by Dr. Mohammad Arjmand, will defend their dissertation titled “3D-Printed Conductive Cellulose Cryogels for Electromagnetic Interference Shielding: Exploring Structural Design, Printability, and Shape Fidelity” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mechanical Engineering.
An abstract for Majed Amini’s dissertation is included below.
Examinations are open to all members of the campus community as well as the general public. Please email mohammad.arjmand@ubc.ca to receive the Zoom link for this exam.
ABSTRACT
This thesis presents the development of three-dimensional (3D)-printed conductive cellulose cryogels designed for electromagnetic interference (EMI) shielding. The motivation for this work arises from the need to find environmentally friendly alternatives to petroleum-based conductive polymers, turning attention to biopolymers derived from natural carbohydrates like cellulose. The research began with optimizing cellulose nanocrystal (CNC) inks to achieve high-resolution 3D structures. This involved creating a “3D-printing” map to demonstrate the relationship between CNC/salt ink rheology and printing fidelity. This map revealed that high fidelity could be achieved within specific concentration ranges, significantly influenced by the type of salt used. Among the ten salts evaluated, FeCl3, CaSO4, and NaHCO3 were particularly effective, enhancing the ink’s rheological properties and enabling precise 3D printing.
To impart conductivity to the cellulose inks, poly(3,4-ethylenedioxythiophene) (PEDOT) was used. This step was crucial for the application of cryogels in EMI shielding. At the macro scale, manipulating the grid dimensions of the 3D-printed cryogels revealed a clear relationship between grid size and shielding effectiveness (SE). Larger grid sizes, ranging from 1 mm to 3 mm, resulted in a 30% reduction in SE and shifted the shielding mechanism from reflection to absorption. At the micro-scale, altering pore sizes from approximately 50 microns to 170 microns demonstrated a similar shift from reflection to absorption, highlighting the impact of pore structure on performance. On the nano-scale, modifications using TEMPO-oxidized cellulose nanofibers (CNFs) coated with PEDOT achieved a high conductivity of up to 546 S/m. This significant enhancement in conductivity greatly improved the EMI shielding effectiveness, outperforming traditional fabrication methods.
Overall, this thesis not only advances the understanding of 3D-printed cellulose cryogels but also establishes their practical applicability in EMI shielding. The innovative methodologies and findings presented offer new avenues for developing sustainable, biocompatible, and lightweight materials, aligning with global demands for eco-friendly technological advancements.
