Extrusion-Based 3D Printing of Poly(propylene fumarate) in a Full-Factorial Design.

3D printing has emerged as an important technique for fabricating tissue engineered scaffolds. However, systematic evaluations of biomaterials for 3D printing have not been widely investigated. We evaluated poly(propylene fumarate) (PPF) as a model material for extrusion-based printing applications. A full-factorial design evaluating the effects of four factors (PPF concentration, printing pressure, printing speed, and programmed fiber spacing) on viscosity, fiber diameter, and pore size was performed layer-by-layer on 3D scaffolds. We developed a linear model of printing solution viscosity, where concentration of PPF had the greatest effect on viscosity, and the polymer exhibited shear thinning behavior. Additionally, linear models of pore size and fiber diameter revealed that fiber spacing and pressure had the greatest effect on pore size and fiber diameter, respectively, but interplay among the factors also influenced scaffold architecture. This study serves as a platform to determine if novel biomaterials are suitable for extrusion-based 3D printing applications.