Stereolithographic 3D printing (SLA) is used as an additive manufacturing method for its high-resolution capabilities to form complex shapes using photopolymers. However, thus far, poor control over printed material properties has limited the technique. This presentation will explain an approach to design, manufacture and characterize composite polymer structures using grayscale SLA. Materials for SLA are primarily limited to crosslinked thermoset acrylate polymer systems, thus restricting the properties and functionality of resulting structures. In this approach, an initial part is printed using a custom SLA printer with a 405nm LED projection system and a spatial light modulator to fabricate a part. Spatially modulating the intensity of the irradiated light onto the precursor resin using gray-scaling allows for volumetric control over material crosslinking density in this fabricated part. A secondary monomer is preferentially in-swollen to areas of low crosslinking density and polymerized to effectively fabricate a3D-printed two-polymer composite using a facile single printing step while maintaining print fidelity. We utilize a linear thermoplastic polymer, otherwise not printable using SLA, for the second material. A deterministic model for polymer conversion in the printing process is utilized to inform printing conditions such that final composite properties can be predicted. This model is validated using confocal Raman microscopy to independently resolve the local concentration of the two-polymer systems throughout the composite using spectroscopy. Preliminary results of reducing layering effects, controlling local conversion using grayscale printing and forming two-material composites are demonstrated using this approach.
- Understand layer-to-layer material properties in stereolithographic printed parts as a function of printing parameters and material properties
- Recognize suitable materials for fabricating composites using SLA
- Develop a strategy to print a composite using SLA and validate print quality at the molecular scale using confocal Raman microscopy