Fabrication of High Permittivity Resin Composite for Vat Photopolymerization 3D Printing: Morphology, Thermal, Dynamic Mechanical and Dielectric Properties

Abstract

The formulation of a high dielectric permittivity ceramic/polymer composite feedstock for daylight vat photopolymerization 3D printing (3DP) is demonstrated, targeting 3DP of devices for microwave and THz applications. The precursor is composed of a commercial visible light photo-reactive polymer (VIS-curable photopolymer) and dispersed titanium dioxide (TiO2, TO) ceramic nano-powder or calcium copper titanate (CCT) micro-powder. To provide consistent 3DP processing from the formulated feedstocks, the carefully chosen dispersant performed the double function of adjusting the overall viscosity of the photopolymer and provided good matrix-to-filler bonding. Depending on the ceramic powder content, the optimal viscosities for reproducible 3DP with resolution better than 100 µm were η(TO) = 1.20 ± 0.02 Pa.s and η(CCT) = 0.72 ± 0.05 Pa.s for 20% w/v TO/resin and 20% w/v CCT/resin composites at 0.1 s−1 respectively, thus showing a significant dependence of the “printability” on the dispersed particle sizes. The complex dielectric properties of the as-3D printed samples from pure commercial photopolymer and the bespoke ceramic/photopolymer mixes are investigated at 2.5 GHz, 5 GHz, and in the 12–18 GHz frequency range. The results show that the addition of 20% w/v of TO and CCT ceramic powder to the initial photopolymer increased the real part of the permittivity of the 3DP composites from ε’ = 2.7 ± 0.02 to ε’(TO) = 3.88 ± 0.02 and ε’(CCT) = 3.5 ± 0.02 respectively. The present work can be used as a guideline for high-resolution 3DP of structures possessing high-ε.

Enhanced Mechanical and Thermal Properties of Stereolithography 3D Printed Structures by the Effects of Incorporated Controllably Annealed Anatase TiO2 Nanoparticles

“…Additives such as amines and silanes that consume dissolved O 2 in the system are the most common ways of preventing oxygen inhibition [25,26]. In addition, weak mechanical properties and deprived accuracy of stereolithography resin (SLR) are widespread problems for most desktop-level SLA techniques, restricting their utilization as functional materials [27]. For this reason, the development of mechanical behaviors of SLRs has been given attention in their applications [28,29].…”

Creep and Recovery Behavior of Continuous Fiber-Reinforced 3DP Composites

“…However, 3DP of continuous fiber-reinforced polymer (CFRP) composites is still a challenge. Therefore, to utilize freedom of fabrication through 3DP and improve their properties, several efforts have been made on synthesis and 3DP of polymers reinforced with particle or fibrous reinforcement [ 8 , 9 , 10 ].…”

Compounding a High Dielectric Constant Thermoplastic Material for Production of Microwave Photonic Crystals through Additive Manufacturing

“…Solution involving AM exist, requiring the use of customized material solutions to deliver the dielectric properties necessary for proper PC performance. Examples include the use of a ceramic suspension in photosensitive resin with the Stereolithography process [10]- [12], and the production of composite thermoplastic filaments to be used in Material Extrusion processes [13].…”