A novel composition including at least one styrene-block copolymer, at least one plasticiser, and particles of a cross-linked polymer having a carboxylate-group density between 2.0 and 12.0 meq/g and an average pore size between 0.005 and 1.0 μm, usable in particular for creating an elastomer matrix suitable for any device of the type device for medical aims such as a patch, a film, a strip or a dressing, preferably a dressing, intended to be applied onto the skin or suitable for any device of the functional textile type such as a sports item.