The environment, mobility, energy, computing and communications all have one thing in common...materials. There are a multitude of them, with known or unsuspected properties, and their study is a science in its own right. At the Institut Polytechnique de Paris, this science is carried out by the M4S (Materials for Society) center. At the crossroads of fields as varied as physics, chemistry, biology, mechanics and applied mathematics, it is a catalyst for collaboration around this transdisciplinary theme.