ABSTRACT
This research reports on the physical and mechanical effects of various filler materials used in direct ink write (DIW) 3-D printing resins. The data reported herein supports interpretation and discussion provided in the research article "Impact of Filler Composition on Mechanical and Dynamic Response of 3-D Printed Silicone-based Nanocomposite Elastomers" [1]. The datasheet describes the model structures and the interaction energies between the fillers and the other components by using Molecular Dynamics (MD) simulations. This report includes mechanical responses of single-cubic (SC) and face-centered tetragonal (FCT) structures printed using new DIW resin formulations (polydimethylsiloxane-based silicones filled with aluminum oxide, graphite, or titanium dioxide). Using MD simulations and mechanical data, the overall flexibility and interactions between resin components are fully characterized.
ABSTRACT
The phase diagram for the thermoreversible gelation of poly(ether ether ketone) (PEEK) in 4-chlorophenol (4CP) was constructed over broad temperature and concentration ranges, revealing that PEEK is capable of dissolving and forming gels in both 4CP and dichloroacetic acid (DCA) up to a concentration of 25 wt %. Highly porous aerogels of PEEK were prepared through simple solvent exchange followed by one of two drying methods of solvent removal from the wet gel: freeze-drying or supercritical CO2 fluid extraction (SC-drying). The field-emission scanning electron microscopy analysis showed that gelation of PEEK in 4CP, followed by SC-drying, produced aerogels with well-defined lamellar aggregates as compared to less ordered aggregates formed from DCA. Mechanical properties (in compression) were shown to improve with increasing density, resulting in equivalent compressive moduli at comparable density, regardless of the preparation method (gelation solvent selection, concentration variation, or drying method). Nitrogen adsorption-desorption isotherms indicate that PEEK aerogels are comprised of mesopores (2-50 nm diameter pores) formed from stacked crystalline lamella. PEEK aerogels prepared using SC-drying exhibit higher Brunauer-Emmett-Teller surface areas than freeze-dried aerogels of comparable density. The ultra-small-angle X-ray scattering/small-angle X-ray scattering (SAXS)/wide-angle X-ray scattering analysis revealed a hierarchical morphology of the PEEK aerogels with structural features from PEEK crystallites to agglomerates of stacked lamella that spanned a wide range of length scales. SANS contrast-matching confirmed that the morphological origin of the principle scattering feature in PEEK aerogels is stacked crystalline lamella. Nitrogen sorption measurements of porosity and the specific surface area of the PEEK aerogels were correlated with the SAXS analysis to reveal a remarkably high surface area attributed to the platelet-like, lamellar morphology. Contact angle and contact angle hysteresis (CAH) revealed that low-density PEEK aerogels (ρ < 0.15 g/cm3) have water contact angles above the superhydrophobicity cutoff angle (>150°) and a very low CAH near 1°.
ABSTRACT
Solutions of poly(ether ether ketone) in dichloroacetic acid have been shown to form monolithic, thermoreversible gels at temperatures ranging from 10 to 140 °C. A phase diagram was constructed over broad concentration and temperature ranges, and the phase boundary suggests an upper critical solution temperature (UCST) behavior. Furthermore, poly(ether ether ketone) (PEEK) gels were solvent-exchanged with water to form hydrogels and subsequently lyophilized to form PEEK aerogels. The PEEK aerogels of density 0.2 g/mL were found to be highly porous and composed of uniform 200 nm morphological features. The crystal structure of the PEEK hydrogels and aerogels was found to be identical to that of melt-crystallized PEEK. The mechanical properties of the PEEK aerogels (in compression) were found to be superior to conventional silicate aerogels of comparable density. This report is the first example of a monolithic, thermoreversible gel of PEEK and the first demonstration of PEEK hydrogels and aerogels.
ABSTRACT
ABC triblock copolymers bearing adenine- and thymine-functionalized external blocks self-assembled into long-range, ordered lamellar microphase-separated morphologies on non-patterned substrates. Intermolecular hydrogen bonding formed thymine-adenine triplets and promoted self-assembly into well-defined lamellae consisting of poly(n-butyl acrylate) soft domains and complementary nucleobase hard domains, while thymine-adenine duplets contributed to superior mechanical properties.
