Shape Memory polymers Preparation, Characterization and Applications

Materials scientists predict that intelligent materials will play a prominent role in the near future.1 Materials that respond dynamically to environmental stimuli can be called intelligent or smart materials. They have significant potential applications in various fields. As a result, research on such materials is actively growing both in academic and industrial sectors. Although the term ‘smart material’ has been conventionally used, all materials are in general responsive (and in this sense smart) but whether they are responsive in an adaptive way is questionable. A ‘very smart’ adaptive response is exhibited if materials/material systems are able to respond dynamically to a number of input stimuli and if this response is repeatable. The ability of polymers to respond to external stimuli such as heat or light is of high scientific and technological significance. Their stimuli-sensitive behavior enables such materials to change certain of their macroscopic properties such as shape, color, or refractive index when controlled by an external signal. The implementation of the capability to actively move into polymers has attracted the interest of researchers, especially in the last few years, and has beenachieved in polymers as well as in gels. Sensitivity to heat, light, magnetic fields, and ion strength or pH value was also realized in gels . In nonswollen polymers, active movement is stimulated by exposure to heat or light and could also be designed as a complex movement with more than two shapes. Besides their scientific significance, such materials have a high innovation potential and can be found, e.g., in smart fabrics , heat-shrinkable tubes for electronics or films for packaging , self-deployable sun sails in spacecrafts , selfdisassembling mobile phones , intelligent medical devices, and implants for minimally invasive surgery . These are only examples and cover only a small region of potential applications. Actively moving polymers may even reshape the design of products. The ability of polymers to respond to external stimuli is of high scientific and technological significance. In the last few years, research activities have been intensified substantially, exploring whether stimuli-sensitive polymers can be designed that move actively. In this review actively-moving materials were classified according to the underlying mechanisms enabling the shape changes: shapememory polymers and shape-changing polymers/shape-changing gels were identified. The application spectra of these materials as well as the current developments were elucidated and general molecular design principles presented. When applicable, a further distinction according to the applied stimulus was made.

کلیدواژه ها:

Shape Memory Polymers ، Dual Shape Memory Materials ، Shape-Changing Capability ، Shape-Memory Capability ، Thermally Induced Dual-Shape Effect ، Covalently Cross-Linked Shape-Memory Polymers ، Thermoplastic Shape-Memory Polymers ، Triple-Shape Polymers