Different Processing Methods to Obtain Porous Structure in Shape Memory Polymers
In the last few years, clinical procedures undergone huge modifications. Among them, mini-invasive surgery has modified the clinical practice and the quality of life of patients. Shape Memory Polymers (SMPs), a class of stimuli-responsive materials, can be considered ideal candidates for the design of devices for mini-invasive surgical procedures. Such a device can be inserted in a packed in, temporary shape and later can expand at body temperature. A bone defect could be filled by a SMP porous structure, that improves the tissue integration and healing. In this work, two different processing techniques to obtain porous shape memory polymer scaffolds from Calo MER™ and MM-4520, two SMPs, are presented. Porous structures were obtained by micro-extrusion with different chemical foaming agents or with sodium chloride, or by solvent casting/particulate leaching. The morphology, the thermo-mechanical and the shape recovery properties of the SMP porous samples were investigated. Tridimensional porous structures showed a well interconnected morphology, with a pore size in the range aimed for bone interaction applications. The shape memory properties were not significantly affected by the transformation processes: a good ability of recovering the original shape was verified. Therefore, the porous structures, obtained from these SMP materials, appear adequate for an use as bone filler.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
S. Farè et al., "Different Processing Methods to Obtain Porous Structure in Shape Memory Polymers", Materials Science Forum, Vols. 539-543, pp. 663-668, 2007