Multi-functional dielectric materials: where do we come from? Where do we want to go?

Electrically insulating polymers and glasses are very suitable as matrix materials for a large variety of functional molecules or functional micro- or nano-particles. In addition to being good host materials, dielectrics may also exhibit their own applications-relevant functions such as charge storage (space-charge electrets), piezo-, pyro-, or ferro-electricity (dipole electrets). Here, a number of recent examples are briefly described, and some possibilities for combining various functions (e.g., low or high dielectric permittivity, (an)isotropic conductivity, piezoelectricity, pyroelectricity, magnetostriction, electro-optic effects, other optical nonlinearities, photo- or electroluminescence, sensitivity to electromagnetic or other radiation, sensitivity to certain chemicals) in a single multi-component material are discussed. It is of course impossible to predict the future, but it may be possible to initiate or strengthen national, European and international research activities and consortia along the lines roughly sketched here.