High Resolution 3D Printing of Hydrogel Composite

Abstract

Hydrogel composite materials and functional device fabrication have broad applications particularly in energy, water and biomedical sectors, while the associated additive fabrication remains challenging. This thesis investigates the key parameter of 3D printing hydrogels, dye concentration in PEGDA-based inks, and its influence on the printing resolution and accuracy. In particular, two dye concentrations, 0.05% and 0.1%, were examined to assess their impact on print quality under varying energy levels in a stereolithography (SLA) 3D printing process. The study was conducted in two stages: In the first stage, energy-thickness curves were obtained to determine the energy required to achieve a target layer thickness of 20 microns for each dye concentration. Results showed that while the 0.05% dye concentration required higher energy to initiate polymerization, it offered superior control at low energy levels. Conversely, the 0.1% dye concentration was more effective at higher energy levels, preventing over-curing and allowing for finer resolution.

In the second stage, optimized energy settings derived from the energy-thickness curves were applied to print models with complex geometries. Optical imaging and SEM analysis have confirmed that the 0.05% dye concentration provides outstanding print accuracy and sharp structures for intricate designs, such as pyramid, microporous, and sponge-inspired models. Notably, the sponge-inspired structure demonstrated water absorption capabilities, showcasing the potential of these hydrogel structures for functional applications.

In addition to 3D printing experiments, this thesis has explored various hydrogel composites in terms of their swelling behavior and evaporation rates in dark environments. Composite hydrogels incorporating HEA and NIPAM monomers can significantly enhance the water absorption and release performance of PEGDA-based hydrogels. HEA-based composites enable the highest evaporation rates, making them suitable for applications in solar vapor generation. Meanwhile, NIPAM-rich composites exhibit substantial swelling, ideal for water-retentive applications.

This thesis underscores the importance of dye concentration optimization in achieving high-resolution 3D-printed hydrogels and demonstrates the effectiveness of composite hydrogel formulations in enhancing water management properties. The findings contribute to the development of advanced hydrogel materials with potential applications in solar-driven water purification, microfluidics, and moisture-responsive devices.

Date of Award	16 Dec 2024
Original language	American English
Supervisor	TJ Zhang (Supervisor)