All-aromatic polyimides demonstrate excellent thermomechanical properties for high temperature applications. 3D printing of pyromellitic dianhydride, 4,4’-oxydianiline (PMDA-ODA) using mask-projection stereolithography (SLA) involves precursor polymers containing acrylate groups, enabling light-induced, chemical crosslinking for spatial control in the gel state. Thermal treatment of the printed parts form PMDA-ODA polyimide with isotropic shrinkage. Alternatively, we will describe UV-curable polyamic acid (PAA) salts via vat photopolymerization (VP) and direct ink write (DIW) methods. Tuning the rheology enabled the minimization of shrinkage and warping. Our stereolithographic research also involves simultaneous thiol-ene step-growth chain extension, acrylate crosslinking during 3D printing to overcome VP challenges. Liquid polybutadiene oligomer/dithiol resin cures selectively forming high-strain, elastic parts. Photorheology elucidated curing as a function of resin composition and UV intensity. This work expands additive manufacturing (AM) by a solvent-free resin with a processable oligomer and elastic properties of a higher molecular weight polymer. This lecture will also highlight our most recent efforts with a facile two-step synthesis to afford PEG-based supramolecular polymers using a low molecular weight PEG end-functionalized with quadruple hbonding cytosine derivative, ureido-cytosine, 3D printed via extrusion-based AM. Rheology revealed a temperature dependent viscosity due to hbonds dissociation, association enabling tuning viscosity. We have also focused on the synthesis, characterization of poly(lactide-co-glycolide) (PLGA)-based photoactive precursors to 3D print tissue scaffolds via SLA. Ring-opening polymerization of lactide and glycolide yields a PLGA-diol, then functionalized to PLGA-diacrylate. Presence of photo-initiator yields a crosslinked biodegradable material.

Predicting 3D printability of functional polymers: balancing rheology with reactivity

2019 Spring National Meeting

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