Scientists have created segmented polyurethane elastomers with mechanochromic and self-reinforcing features. The development is useful for intuitive damage detection and the creation of adaptive materials.

An important ability of such biological tissue as muscles is self-healing and self-reinforcement. It occurs in response to damage caused by external forces. Most artificial polymers are irreversibly destroyed under sufficient mechanical stress.
This makes them less useful for producing artificial organs, for example. But what if you can create polymers that react chemically to mechanical stress and use this energy to improve their properties?

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

The team created segmented polyurethane polymer chains with hard and soft functional segments. The soft segments contain DFSN molecules that act as their “weakest link,” with both halves connected by a single covalent bond. The side chains of the soft segments terminate in methacryloyl units. When a polymer is subjected to mechanical stress, such as simple compression or tension, the DFSN molecule splits into two equal cyanofluorene (CF) radicals. In contrast to DFSN, these CF radicals turn pink, making it easy to detect damage visually.

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

Professor Hideyuki Otsuka 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.