Poly(Allyl Glycidyl Ether Succinate) (PAGES) for Solvent Free Vat Photopolymerization 3D Printing of Degradable Medical Devices

Abstract

Additive manufacturing has enormous potential to change the medical industry with its inherent customization and ability to produce complex geometries. Vat photopolymerization (VPP), a type of additive manufacturing that cures liquid resins into solid 3D printed parts using light, is especially renowned for its high resolution and efficiency. While there are many commercially available resins for VPP printing, nearly all of them produce non-degradable 3D printed parts. Current efforts towards degradable resins are limited to functionalizing degradable polymers with photopolymerizable end groups, which results in a network that is only partially degradable. Other efforts utilizing thiol-ene reactions can produce fully degradable networks, but struggle with slow degradation rates and significant amounts of part shrinkage from the use of solvents in the resin to achieve a printable viscosity. The development of new, degradable resins for 3D printing could allow VPP to be used to manufacture temporary medical implants that could be degraded and resorbed into the body. Herein, poly(allyl glycidyl ether succinate) (PAGES) polyester was synthesized, characterized, and used to formulate solvent free 3D printable resins for both digital light processing (DLP) and continuous liquid interface production (CLIP) 3D printing on the kg scale. PAGES resins are unique because they are inherently low viscosity due to the comb-like polymer architecture, allowing them to be printed completely solvent free at room temperature, unlike any other thiol-ene resins currently reported. Solvent free printing not only improves part tolerancing by eliminating the part shrinkage issue that plagues other resins but also improves the mechanical integrity of the 3D printed parts by promoting the formation of a more ideal network and avoiding cracking, warping, and residual stress formation associated with solvent evaporation. 3D printed PAGES networks displayed tunable mechanical properties similar to that of soft tissue and adjustable degradation rates ranging from 1 week to over 1 year. Large animal preclinical studies in a sheep vascular model indicated that PAGES 3D printed networks were both degradable and biocompatible in a living system, showing complete resorption of a 3D printed sheath device after four months in vivo with similar levels of inflammation as occurred in control procedures. Overall, this work highlights the development of a library of solvent free PAGES resins for VPP 3D printing that are high resolution, scalable, tunable, degradable, biocompatible, and resorbable, positioning them as an ideal candidate for manufacturing temporary medical implants.