Design and characterization of biocompatible shape memory polymer (SMP) blend foams with a dynamic porous structure

- We fabricate SMP foams with the 80/20, 65/35, and 50/50 TPU/PLA blends and neat TPU.
- Porous 80/20, 50/50 TPU/PLA blends & neat TPU contain recoverable porous structures.
- We capture the pore recovery process in neat TPU visually with a CCD camera.
- We measure the shape recovery force of the porous 80/20 TPU/PLA blend.
- The force exerted by each dynamic pore in the 80/20 TPU/PLA blend was estimated.

This study presents a comprehensive morphological, physical, and shape memory characterization of biocompatible shape memory polymer (SMP) blend foams composed of thermoplastic polyurethane (TPU) and polylactic acid (PLA). The TPU/PLA blend compositions studied were 80/20, 65/35, and 50/50 in weight percentage. The influence of blend composition and processing conditions on the pore morphology of the foams were studied with the scanning electron microscope (SEM). The results showed that all the TPU/PLA compositions formed close-celled porous structures. A number of physical characteristics of the foams were characterized, including relative density, pore density, porosity, and average pore size. The shape memory properties of the porous structure formed in the foams were investigated. The 80/20 and 50/50 TPU/PLA blends, and neat TPU contained a dynamic porous structure that contracted uniformly upon shape recovery. The recovery of the pores in the neat TPU was captured with a CCD camera in real time and the recovery force of the 80/20 TPU/PLA blend was measured with a custom built force sensor. These shape memory polymer foams are currently under investigation for biomedical applications, such as gastro-retentive drug delivery systems and wound dressings.