Abstract
Polyvinyl alcohol (PVA) has versatile applications, including its use as sacrificial materials, hydrogels, and surface modifiers in both conventional and 3D printing methods. In this thesis, we explore how different 3D printing techniques—stereolithography (SLA), direct ink writing (DIW), and fused deposition modelling (FDM)—can utilize PVA as a functional material. Specifically, we demonstrate its application as a coating for SLA 3D-printed molds, a binder for ceramic 3D printing, and a mechanically stable material for FDM 3D printing.
SLA 3D-printed molds contain uncured oligomers, preventing the PDMS curing at the interface and thus challenging to replicate the surface features from the mold. We demonstrate the use of PVA as a coating over 3D-printed molds to mitigate the inhibition of polydimethylsiloxane (PDMS) curing at the interface. Here, PVA serves as a physical barrier between the SLA 3D-printed mold and PDMS, resulting in a fully cured PDMS replica with high print fidelity (250–500 μm). In DIW 3D printing of ceramics, previous research has focused on the usage of multiple additives such as dispersants, catalysts, and photo initiators, which can affect the rheology and printability of the ink. To address the challenges arising from the use of multiple additives that affect ink printability and post-processing methods, we propose a simple method to 3D print ceramics such as 8YSZ and TiO₂ using PVA as a single additive. We demonstrate the successful fabrication of 3D structures using an ink composed of 55% w/w ceramic and 15% w/v PVA, printed in different embedding media such as NaOH for 8YSZ and acetone for TiO₂. After sintering, the 8YSZ ceramic exhibits a compressive strength of 0.8 ± 0.02 MPa and the TiO₂ ceramic exhibits a compressive strength of 3.6 ± 0.5 MPa. For FDM 3D printing, where PVA is traditionally used as a sacrificial component due to its moisture sensitivity, we enhance its moisture resistance and mechanical stability through physical crosslinking with 6 M NaOH, reducing its swelling from 169% to 0.041%. We also systematically investigate the PVA composites by incorporating BaTiO₃. The resulting PVA/BaTiO₃ composites achieve the tensile strength of 10.5 ± 2.64 MPa and the flexural strength of 30 ± 5.4 MPa. Overall, this thesis utilizes the PVA properties to solve some existing issues such as inhibition of PDMS curing on SLA 3D printed molds and provide alternative simplified pathways for ceramic 3D printing. The findings contribute to the development of advanced materials and methods, particularly in the fields of microfabrication, and 3D printing of ceramics and polymers.