Shape Memory Polymer Porous Structures for Mini-Invasive Surgical Procedures

In the recent past, clinical procedures underwent huge modifications. Among them, mini-invasive surgery has modified the clinical practice and the quality of life of patients. All these evolutions are strictly correlated to the advancement in materials science. Shape Memory Polymers (SMPs), a novel class of stimuli-responsive materials, can be considered ideal candidates for the design of devices for mini-invasive surgery. Such devices can be inserted in a compact temporary shape and subsequently expanded at body temperature: a bone defect, e.g., could be filled by a filler made of SMPs. With the aim of promoting tissue integration and healing, these structures should present a suitable porosity. In this work two different processing techniques to obtain shape memory polymer scaffolds from Calo·MER™, a SMP, are presented. Porous structures were obtained by micro-extrusion, with different chemical expanding agents or by particulate leaching with salt. Morphology, thermo-mechanical and shape recovery properties of the SMP porous samples were investigated. The obtained foams show a well interconnected morphology, with a pore size in the range suitable for bone applications. Shape memory properties were not significantly affected by the transformation processes: a good ability of recovering the original shape was verified. Therefore, foams obtained from these materials could be used to fabricate devices for mini-invasive surgical procedures.