under exposure to light. Polycaprolactone (polymorph) can be molded by immersion in hot water. Self-healing materials have the intrinsic ability to repair damage due to normal usage, thus expanding the material's lifetime. Dielectric elastomers (DEs) are smart material systems which produce large strains (up to 500%) under the influence of an external electric field. Magnetocaloric materials are compounds that undergo a reversible change in temperature upon exposure to a changing magnetic field. Smart self-healing coatings heal without human intervention. Thermoelectric materials are used to build devices that convert temperature differences into electricity and vice versa. Chemoresponsive materials change size or volume under the influence of external chemical or biological compound. Smart materials have properties that react to changes in their environment. This means that one of their properties can be changed by an external condition, such as temperature, light, pressure, electricity, voltage, pH, or chemical compounds. This change is reversible and can be repeated many times. There is a wide range of different smart materials. Each offer different properties that can be changed. Some materials are very good and cover a huge range of the scales. See also Smart polymer Programmable matter Sensors Actuators Artificial muscles Thermally induced shape-memory effect (polymers) References External links Smart Materials Book Series, Royal Society of Chemistry Artificial materials