Bioinspired Scaffolds with Varying Pore Architectures and Mechanical Properties

摘要

Scaffolds with potential biological applications having a variety of micro-structural and mechanical properties can be fabricated by freezing colloidal solutions into porous solids. In this work, the structural and mechanical properties of TiO_2 freeze cast with different soluble additives, including polyethylene glycol, NaOH or HCl, and isopropanol alcohol, are characterized to determine the effects of slurry viscosity, pH, and alcohol concentration on the freezing process. TiO_2 powders mixed with water and these different additives are directionally frozen in a mold, then sublimated and sintered to create the porous scaffolds. The different scaffolds are characterized to compare the compressive strength, modulus, porosity, and pore morphology. For all scaffolds, the overall porosity remains constant (80-85%). By changing the concentration of each additive, the lamellar thickness, pore area, and aspect ratio vary significantly, showing inverse relationships to both the compressive strength and modulus. The strength is predicted from the pore aspect ratio of the scaffolds when subjected to compressive loading with the primary failure mode identified as Euler buckling. TiO_2 scaffolds freeze cast with different soluble additives are suitable for biomedical applications, such as bone replacements, requiring high porosity and specific pore morphologies.