Despite the fact that materials with shape memoryThey have very good potential for use in various fields, many of them have one feature: they need heat to change their shape. This in turn can be a problem for their use within temperature-sensitive environments, such as the human body. However, the new development of Swiss scientists lacks this drawback, because instead of heat, the material created by them with shape memory uses a magnetically sensitive liquid. Development is reported in Advanced Materials magazine.
How does the shape memory material work?
Designed by scientists from the Swiss InstitutePaul Scherrer and the Zurich Swiss High School of Technology, the material basically uses a silicone-containing polymer with droplets of a special liquid encapsulated inside it. This “magnetorheological fluid” in turn consists of water, glycerin, and also tiny particles of carbonyl iron. The composition of the liquid is similar to milk, in which the fat particles are dispersed (dissolved) in an aqueous solution.
In the normal state, the structure of the material remainssoft and flexible. But one has only to influence it with a magnetic field, and the droplets of the liquid contained in it are lengthened, and the iron particles in it line up along the source of the magnetic field. Thanks to these two factors, there is a 30-fold increase in the rigidity of the material.
In practice, this means that ifthe original shape of the material, and then act on it with a magnetic field, it hardens and retains this shape until the magnetic field is no longer affected. Once this happens, the material returns to its original shape and becomes soft.
In previous studies, scientists have alreadycreated magnetically activated materials with shape memory, consisting of polymers with the content of metal particles. According to Swiss scientists, the peculiarity of their magnetorheological fluid allows their polymer to become more rigid.
Scientists have voiced several potentialuse cases for their new material. For example, medical catheters can be made from it that can change its stiffness after a safe injection into the blood vessels. It will be possible to create self-healing tires for ground-based research spacecraft from it, or to use it in the production of robotics components that can move without the need for motors.
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