title: High-Strength Stereolithographic 3D Printed Nanocomposites: Graphene Oxide Metastability.
abstract: The weak thermomechanical properties of commercial 3D printing plastics have limited the technology's application mainly to rapid prototyping. In this report, we demonstrate a simple approach that takes advantage of the metastable, temperature-dependent structure of graphene oxide (GO) to enhance the mechanical properties of conventional 3D-printed resins produced by stereolithography (SLA). A commercially available SLA resin was reinforced with minimal amounts of GO nanofillers and thermally annealed at 50 and 100 °C for 12 h. Tensile tests revealed increasing strength and modulus at an annealing temperature of 100 °C, with the highest tensile strength increase recorded at 673.6% (for 1 wt % GO). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) also showed increasing thermal stability with increasing annealing temperature. The drastic enhancement in mechanical properties, which is seen to this degree in 3D-printed samples reported in literature, is attributed to the metastable structure of GO, polymer-nanofiller cross-linking via acid-catalyzed esterification, and removal of intercalated water, thus improving filler-matrix interaction as evidenced by spectroscopy and microscopy analyses.
authors.affiliation: Department of Macromolecular Science and Engineering, Case Western Reserve University , Cleveland, Ohio 44106, United States.|Department of Mining, Metallurgical, and Materials Engineering, University of the Philippines , Diliman, Quezon City 1101, Philippines.
authors.forename: Jill Z
authors.initials: JZ
authors.lastname: Manapat
authors.affiliation: Department of Radiology, Case Western Reserve University , Cleveland, Ohio 44106, United States.
authors.forename: Joey Dacula
authors.initials: JD
authors.lastname: Mangadlao
authors.affiliation: Department of Macromolecular Science and Engineering, Case Western Reserve University , Cleveland, Ohio 44106, United States.|Department of Biomedical Engineering, Case Western Reserve University , Cleveland, Ohio 44106, United States.
authors.forename: Brylee David Buada
authors.identifier: http://orcid.org/0000-0001-5134-0783
authors.initials: BD
authors.lastname: Tiu
authors.affiliation: Department of Chemical Engineering, Case Western Reserve University , Cleveland, Ohio 44106, United States.
authors.forename: Grace C
authors.initials: GC
authors.lastname: Tritchler
authors.affiliation: Department of Macromolecular Science and Engineering, Case Western Reserve University , Cleveland, Ohio 44106, United States.
authors.forename: Rigoberto C
authors.identifier: http://orcid.org/0000-0002-2899-4778
authors.initials: RC
authors.lastname: Advincula
keywords: additive manufacturing; graphene oxide; mild annealing; polymer nanocomposites; stereolithography; thermal postcuring