Memory-Effects of Polymers and their relevance for Biomedical Applications

The thermally-induced shape-memory effect is the capability of a material to change its shape in a predefined way in response to heat. In shape-memory polymers (SMP) this shape change is the entropy-driven recovery of a mechanical deformation, which was temporarily fixed by formation of physical crosslinks after application of an external stress. Besides this dual shape effect recently triple and multiple shape effects as well as temperature memory and magnetic memory effects have been introduced. Actively moving materials have a high application potential in medicine especially in minimally-invasive surgery (e.g. sutures or stents). As each application is demanding a specific combination of intrinsic properties (e.g. elasticity) and functions (e.g. cell/tissue-specific compatibility) often multifunctional materials are required. Therefore active polymer systems are developed, which allow tailoring of macroscopic properties by only small changes in molecular parameters. Such multifunctional SMPs need to be designed carefully to integrate the different functions. Finally, challenges arising during development of biomedical products and their translation to the clinical application will be discussed.