Morphology and properties of porous and interconnected poly(ε- caprolactone) matrices using solid and microcellular injection molding

In this research, an approach for mass producing highly porous and interconnected poly(ε-caprolactone) (PCL) matrices potentially suitable for tissue engineering scaffolds was developed. The biocompatible, biodegradable, and bioresorbable PCL was first melt compounded with poly(ethylene oxide) (PEO) resin and sodium chloride (NaCl) particles and then injection molded into both solid and microcellular PCL/PEO/NaCl samples using a machine equipped with a supercritical fluid (SCF) system. Nitrogen (N ₂) at the supercritical state was used as both a plasticizer and a physical blowing agent, thereby imparting moldability to the blend even with an ultra-high salt particulate content and a foamed structure in the molded samples. The water soluble sacrificial polymer, PEO, as well as NaCl particulates in the molded samples, were leached by deionized water to produce a highly porous and interconnected microstructure. The morphology, porosity, water absorption, and percentage recovery of both solid and microcellular samples were observed and calculated. In addition, the mechanical performance of the scaffolds was characterized using dynamic mechanical analysis (DMA) and conventional compression testing under wet conditions. The results showed that the porosity of microcellular samples increased by 7% in comparison with their solid counterparts, reaching up to ∼72%. The microcellular samples still have large storage, loss, and compressive moduli, although they showed a slight decrease by comparison with those of solid samples. Both solid and microcellular samples showed a good capacity of recovery. The compressive thickness was recovered up to ∼80% in the first 24 h after compression.