The new polymer reacts to mechanical stress almost like muscle

An important ability of biological tissue such as muscles is self-repair and self-strengthening.It

occurs in response to damage caused by external forces.Most man-made polymers are irreversibly destroyed under sufficient mechanical stress. This makesBut what if it was possible to create polymers that react chemically?and used this energy to improve their properties? 

In a recent study published inAngewandte Chemie International Edition, a group of scientists from the Tokyo Institute of Technology, Yamagata University, and the Sagami Institute of Chemical Research, Japan, have made significant strides in the field of bulk self-hardening substances. Their new polymerIt reacts to mechanical stress almost like muscles.

Synthesized segmented polyurethanes (SPU),containing di-fluorenyl succinonitrile (DFSN) fragments and methacryloyl groups. The resulting elastomers formed pink cyanofluorene radicals and changed color when compressed or stretched. This is the first example of force-driven crosslinking reactions achieved only by stretching or contracting a bulk film. Credit: Tokyo Tech

The team created segmented polyurethane polymer chains with rigid and soft functional segments.The soft segments contain DFSN molecules acting as their "weakest link," with both halves connected by a single covalent bond.The side chains of the soft segments terminate in methacryloyl links.mechanical stress, e.g., simple compression or stretching, the DFSN molecule is split into two equal cyanofluorene (CF) radicals.These CF radicals, unlike DFSN, take on a pink color, which allowsIt is easy to visually detect damage.

We have successfully developed unprecedentedmechanoreactive polymers that exhibit color change, fluorescence, and self-reinforcing ability. This is a significant progress in fundamental research of mechanochemistry and its applications in materials science.

Prof. Hideyuki Otsuka, who led the study

The attractive properties and functionality of the developed polymers are useful, for example, for intuitive damage detection and the creation of adaptive materials.

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Mechanochemistry is a branch of chemistry that studies the change in the properties of substances and their mixtures, as well as physicochemical transformations under mechanical stress, during deformation, friction, and shock compression.