A super shape-shifting polymer holds 1000 times its mass and has been developed by a scientific team at the University of Rochester. Professor Mitch Anthamatten led the project that yielded exciting results.
Polymers are drawing increasing attention. Their shape-shifting properties deem these materials useful in a wide variety of applications. The newly developed super polymer sports new features which allow it to change shape at body temperature and lift 1000 times its mass. Medical applications will gain tremendously once the super polymer is widely introduced.
Chemical engineering professor Mitch Anthamatten and Yuan Meng, graduate student, tweaked the crystallization process that a polymer undergoes when it is stretched or cooled. This shape-memory polymer maintains one shape until it is prompted back to its original shape by a temperature trigger.
The crystallization process entails polymer chains to stretch locally as the material is stretched too. Small parts of the polymer chains align in the direction of the stretching, forming crystallites. Once locked, crystallites retain the polymer in a deformed shape. The more crystallites are formed with increased pressure, the more stable the deformed shape becomes. As such, most polymers are faced with a difficulty in returning to their original shape.
Tweaking this process was key to achieving the shape-memory polymer developed in the University of Rochester laboratory. Tuning the temperature trigger involved the introduction of molecular linkers which could effectively connect polymer strands. These molecular linkers don’t stop the crystallization process. They do however inhibit the stable formation of crystallites.
As such, the research team altered molecular linkers types and numbers until the melting point and temperature trigger could be established with precision. This resulted in the shape-memory polymer which also stores a large amount of elastic energy.
Successful tests prompted the research team to announce that a super shape-shifting polymer holds 1000 times its mass. When the super polymer is heated at body temperature, the crystallites break and the polymer returns to its original shape. According to professor Anthamatten:
“Our shape-memory polymer is like a rubber band that can lock itself into a new shape when stretched. But a simple touch causes it to recoil back to its original shape”.
The second goal that the team set was to create a material that can store large amounts of elastic energy. This entails mechanical work as a result of the shape-shifting process. Shape memory polymers are tested against their surroundings by pulling or pushing against a given surface. However, mechanical work performed during the shape-shifting process is rarely measured.
The new shape memory polymer was tested for the mechanical work it is able to perform. According to the team, a string of the material the same size of a shoelace can effectively lift one a one liter bottle of soda. As a super shape-shifting polymer holds 1000 times its mass, expect a growing number of applications using the shape memory polymer.
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