Synthesis and Formulation of PCL-Based Urethane Acrylates for DLP 3D Printers.

In this study, three PCL-based polyurethane acrylates were synthesized and further formulated into twelve resins for digital light processing (DLP) 3D printing. Three PCL diols with different molecular weights were synthesized via ring-opening reaction of ε-caprolactone on diethylene glycol, with the catalyst stannous octoate. Isophorone diisocyanate (IPDI) was reacted with 2-hydroxyethyl acrylate (2-HEA) and the PCL diols form PCL-based polyurethane acrylates. Twelve resins composed of different percentages of PCL-based polyurethane acrylates, poly (ethylene glycol) diacrylate (PEGDA), propylene glycol (PPG) and photo-initiator were further printed from a DLP 3D printer. The viscosities of twelve resins decreased by 10 times and became printable after adding 30% of PEGDA. The degree of conversion for the twelve resins can reach more than 80% after the post-curing process. By changing the amount of PEGDA and PPG, the mechanical properties of the twelve resins could be adjusted. PUA530-PEG-PPG (70:30:0), PUA800-PEG-PPG (70:30:0), and PUA1000-PEG-PPG (70:30:0) were successfully printed into customized tissue scaffolds. Twelve PCL-based polyurethane photo-curable resins with tunable mechanical properties, cytotoxicity, and degradability were successfully prepared. With the DLP 3D printing technique, a complex structure could be achieved. These resins have great potential for customized tissue engineering and other biomedical application.