Biodegradable Porous Poly(ε-caprolactone)s: Emulsion Templating Stabilization and Ring-Opening Cross-linking

PolyMIPEs are emulsion-templated macroporous polymers synthesized within medium internal phase emulsions (MIPEs), emulsions with dispersed phases between 40 and 74 vol %. Here, biodegradable poly(ε-caprolactone) (PCL) polyMIPEs, synthesized using ring-opening polymerization within oil-in-oil MIPEs, were cross-linked with either a novel combination of pentaerythritol (initiator) and glutaraldehyde (star cross-linker) or with bis(ε-caprolactone-4-yl). PolyMIPEs from emulsions stabilized using a surfactant, nanoparticles (NPs), or innovative polymer brushes (PBs) with predesigned arms were compared. The polyMIPEs exhibited moduli similar to those of soft tissues, withstood compressive strains up to 70%, and underwent complete hydrolytic degradation. PolyMIPEs from NP-stabilized MIPEs exhibited closed-cell structures with relatively large voids and lower moduli, while polyMIPEs from PB-stabilized MIPEs exhibited significantly smaller voids and higher moduli, revealing an unexpected connection between the void diameters and the mechanical properties. This work lays the foundation for modifying the macromolecular structures, porous structures, and properties of macroporous PCL monoliths through the cross-linking and emulsion-stabilization strategies.