Development and characterization of porous membranes with sandwich-like structure based on biocompatible, immiscible polymer blends

Porous membranes based on poly(D,L-lactide)/poly(E-caprolactone) (PDLLA/PCL) blends intended for use as scaffolds in tissue engineering, characterized by an enrichment of the PCL minor phase onto the surfaces, have been prepared. This peculiar structure, that has been called sandwich-like as one of the component mainly locates on the surfaces while the other component is the main constituent of the core phase, has been obtained through a solvent–non solvent technique combined with the leaching out of an appropriate porogen. The membranes have been characterized through 1H-NMR spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The spontaneous realization of the sandwich structure has been confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The influence of the addition of PCL–poly(ethylene oxide) (PEO) copolymers of different architecture and composition as compatibilizing agent on the morphology and structure of membranes has been investigated. Moreover, a new synthetic strategy to prepare a PCL-g-PEO graft copolymer is reported. A mechanism that gives rise to the phenomenon of PCL surface enrichment is proposed.