[Fibers and Fabrics] European and American Scientists Develop Strain-Blocking Biocompatible Materials

Biological tissues have complex mechanical properties, are flexible but strong, and synthetic materials are difficult to reproduce. Recently, a study conducted jointly by CNRS, the European Synchrotron Radiation Laboratory (ESRF) and American scientists prepared a biocompatible composite material that not only has the mechanical properties of biological tissues, And when the force deforms, its color will change, just like the skin of a chameleon. The research results are published in the latest issue of the journal Science. The researchers said that the new material will promote the development of biomedical devices.

In order to prepare medical implants, it is necessary to select materials having similar mechanical properties to biological tissues in order to prevent inflammation or tissue necrosis. Many tissues, such as skin, gut wall, and myocardium, are very soft but harden when stretched. Therefore, synthetic materials have so far failed to reproduce this behavior.

In this study, researchers used a unique triblock copolymer to develop a synthetic material with biological tissue properties—a physically cross-linked elastomer. They found that by carefully selecting the structural parameters of the polymer, the strain curve of the material is the same as that of biological tissue (in this study, pig skin), and it has good biocompatibility and does not require solvents and other additives. In the figure below, the upper left panel shows the molecular structure of the synthesized plastomer; the upper right panel shows the supramolecular structure assembled from plastomers; the lower left panel shows the stress-strain curve of the pigskin sample (transverse or longitudinal section) and the plastomer; The following figure shows the color change of the plastomer (the edge is less blue than the light receiving angle).

Interestingly, this new material can also change color when deformed. Scientists explained that this physical phenomenon is caused by the light scattering of the polymer structure. Atomic force microscopy and X-ray diffraction data indicate that the end blocks of these polymers are assembled into nanospheres distributed in a brush-like polymer matrix. Light interferes with this micro-phase separation structure, and spheres produce different colors because of the distance, so when the material is stretched, it changes color. The same mechanism, to a large extent, explains the reasons for the discoloration of the chameleon.

The researchers said that the mechanical properties (elasticity, strain curve) and optical properties of this newly synthesized polymer are unprecedented. By regulating the length or density of the side chains, the properties of the polymer can be adjusted, and it is hopeful to develop medical implants or personalized fakes. Body (blood vessels, intraocular implants, etc.) and materials with new resilience.