Optimization of Photocrosslinkable Resin Components and 3D Printing Process Parameters
13 Pages Posted: 14 May 2019 First Look: Accepted
The role of 3D printing in the biomedical field is growing. In this context, photocrosslink-based 3Dprinting procedures for resorbable polymers stand out. Despite much work, more studies are needed on photocuring stereochemistry, new resin additives, new polymers and resin components. As par tof these studies it is vital to present the logic used to optimize the amount of each resin constituent and how that effects printing process parameters.The present manuscript aims to analyze the effects the poly(propylene fumarate) (PPF) resin components and their effect on 3D printing process parameters. Diethyl fumarate (DEF),bisacylphosphine oxide (BAPO), Irgacure 784, 2-hydroxy-4-methoxybenzophenone (HMB) and,for the first time, in biomedical 3D printing, ethyl acetate (EA), were the resin components under investigation in this study. Regarding printing process parameters, Exposure Time, Voxel Depth,and Overcuring Depth were the parameters studied. Taguchi Design of Experiments was used tosearch for the effect of varying these resin constituent concentrations and 3D printing parameters onthe curing behavior of 3D printable PPF resins.Our results indicate that resins with higher polymer cross-link density, especially those with a higher content of PPF, are able to be printed at higher voxel depth and with greater success (i.e.,high yield). High voxel depth, as long as it does not sacrifice required resolution, is desirable as it speeds printing. Nevertheless, the overall process is governed by the correct setup of the voxeldepth in relation to overcuring depth. In regards to resin biocompatibility, it was observed that EAis more effective than DEF, the material we had previously relied on. Our preliminary in vitrocytotoxicity tests indicate that the use of EA does not reduce scaffold biocompatibility as measured by standard cytotoxicity testing (i.e., ISO 10993-5). We demonstrate a workpath for resin constituent concentration optimization through thin film tests and photocrosslinkable process optimization.
Keywords: Poly(Propylene Fumarate), Polymer Resin, Cytotoxicity, Stereolithography (SLA), Digital Light Processing (DLP), Mask Projection, 3D Printing, Additive Manufacturing, Scaffold, Bone Tissue Engineering
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