3D Printing of Smart Structural Composites by Thermoelectric Extrusion with Molecular Precision

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A smart structural composite provides structural support with built-in sensing (temperature, pressure, flow and load) functionalities. Recent advances in intelligent infrastructure and the proliferation of wearable gadgets and smart prosthetics have created a need for manufacturing affordable, customizable, and precise smart structural composites. Among current manufacturing methods, 3D printing can directly build customizable parts from computer models, but lack the ability to incorporate additives (such as piezoelectric nanoparticles) that provide sensing functionality. Most polymer-based 3D printing methods build parts by layer-by-layer deposition of a polymer extruded out of a nozzle above its melting temperature and have limited control of the polymer microstructure as it cools down. This leads to poor dimensional accuracy of 3D printed parts in comparison with parts fabricated from traditional manufacturing processes. This award supports fundamental research to create new knowledge in 3D printing and its application in healthcare, education, and engineering will foster new economic activity. This award also supports participation of women and underrepresented groups in engineering research and outreach efforts by the investigators with middle and high school students.The objective of this research is to formulate relationships between an applied electric field during the extrusion of thermoplastic ionomer/piezoelectric composite and its resulting material properties (e.g., optical clarity, strength, piezoelectric strain coefficient, and interfacial adhesion between polymer matrix and nanoparticles). In a thermoplastic ionomer, the difference in polarity between the hydrocarbon chain and ionic group creates an electrostatic driving force and results in aggregation of ions. In this context, there exists a knowledge gap on the aggregation of ions in a thermoplastic ionomer above its melting temperature under the influence of an externally applied electric field. In order to understand how an electric field (greater than the electrostatic force of aggregation) applied to a mixture of thermoplastic ionomer/piezoelectric additive affects aggregation morphology (size, distribution in the matrix and around nanoscale additives), the research team will conduct experimental research and coarse-grained molecular dynamics simulations of a representative thermoplastic ionomer with piezoelectric additives (ethylene/methacrylic acid with PZT-5H and PVDF).