Customized Fading Scaffolds: Strong Polyorthoester Networks via Thiol-Ene Cross-linking for Cytocompatible Surface-Eroding Materials in 3D Printing.

Polyorthoesters are a highly desirable class of cytocompatible materials that are able to rapidly surface-erode. Despite their promise, their mechanical weakness and complex synthesis have limited their processability and application in advanced technologies. Herein, we report a readily accessible family of cross-linked poly(orthoester-thioether) (POETE) materials that are suitable for processing via photopolymerization. Polymer networks are accessed through bifunctional orthoester precursors using simple thiol-ene addition chemistry. The mobility of the polymer chains and the cross-linking density within the polymer structure can be tuned through the choice of the monomer, which in turn presents customizable thermal and mechanical properties in the resulting materials. The photopolymerizability of these POETE materials also allows for processing via additive manufacturing, which is demonstrated on a commercial 3D printer. Post-processing conditions and architecture are crucial to material degradability and are exploited for programmed bulk-release applications with degradation rate and release time linearly dependent on the specimen dimensions, such as strand or shell thickness. Analogous to acid-releasing polylactide materials, degradation products of the POETE materials show cytocompatibility below a certain concentration/acidity threshold. This research highlights the simplicity, versatility, and applicability of POETE networks as cytocompatible, surface-eroding materials that can be processed by additive manufacturing for advanced applications.