EAGER: Fabrication and Characterization of 3D Ceramic-Coated Polymer Scaffolds

Vanderbilt University, Nashville TN

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: This EAGER project capitalizes on new deposition technologies and investigates the formation of ceramic films deposited onto polymer structures to better understand how the composition and microstructure of the ceramic depends on the deposition conditions. This information is critical to be able to fabricate three-dimensional ceramic structures by coating a polymer template with a ceramic film. Three-dimensional ceramic structures have a wide variety of applications, from catalyst supports for energy conversion or chemical processing to medical implants and biological studies. The target application for this work is ceramic structures that mimic the chemical composition, microstructure, porosity, and surface morphology of bone. With properties similar to bone, these structures are being used to perform fundamental studies, such as investigation of tumor cell migration and invasion as well as drug screening. Graduate and undergraduate students are actively involved in this multidisciplinary work, gaining skills important to their future success. TECHNICAL DETAILS: This EAGER grant investigates fundamental mechanisms controlling the processing/property/performance relationships of calcium phosphate (CAP) films deposited onto 2D and 3D polyurethane (PUR) templates to form structures with properties similar to bone. For most applications, the surface composition and microstructure of the ceramic, and the pore size/porosity of the structure significantly impact a porous ceramic structure's performance. 3D printing is an exciting new way to fabricate polymer structures with defined porosity and pore size. The conformal CAP coatings are deposited using a low temperature atomic layer deposition process. The scientific issues involved in this project encompass two of the eight grand challenges for ceramic science that were identified during a 2012 NSF-sponsored workshop: 1) predicting and controlling heterogeneous microstructures, and 2) control of ceramics far from equilibrium. Prof. Rogers uses 2D structures on silicon, fabricated using a process identical to that used to fabricate the 3D structure, to study how the chemical composition, microstructure, and mechanical properties of the CAP/PUR system evolve as a function of processing conditions. The as-deposited CAP films are amorphous due to the low synthesis temperature. Post-deposition annealing is used to investigate how the amorphous CAP crystallizes as a function of temperature profile and overall heat duty. The inherently non-equilibrium rapid thermal annealing process facilitates the formation of phases and microstructures in the thin CAP films that are not attainable through thermodynamically-controlled processing of bulk materials. The breadth of topics involved in this project (hard and soft materials, processing, characterization, computer programming, reactor design/construction, 2D vs. 3D materials) exposes the graduate and undergraduate students on the project team to many aspects of academic and industrial research and problem solving. The skills they attain through this project will benefit them throughout their career.