From a scientific Curiosity to functional Materials Auxetic Materials

Auxetic materials exhibit an unusual behavior: they become thicker when stretched and thinner when compressed. When Roderic Lakes succeeded in transforming conventional polymer foams into auxetic materials, no one would have guessed that this was the birth of a new, highly interdisciplinary branch of research that has developed extremely rapidly over the past 30 years. At the macroscopic level, auxetics quickly became the domain of designers and engineers, who focused on optimizing the properties of new 'metamaterials. In the nanoscopic field, chemists have recently made important advances in the creation of auxetic polymers. The article discusses certain auxetic structuring concepts as examples and shows how nano- or microscopic kinematics can cause negative Poisson numbers at the macroscopic level.