FUNCTIONAL COLLOIDS - STRUCTURE FORMATION AND CHEMISTRY ON A NANOMETER-SCALE

Colloid chemistry is the science of the finely divided state of materi al. Colloids are small units of gas, a liquid, or a solid whose size i s measured in nanometers. Systems containing or made up of colloids ca n have special properties differing significantly from those of the mo lecules from which the colloid particles are made and from those of th e corresponding bulk material. The colloidal state is therefore someti mes described as the ''fourth state of aggregation''. Fundamental prop erties such as melting point, conductivity, or the optical parameters depend upon particle size. Modem colloid chemistry thus provides consi derable scope for the production of new materials with new combination s of properties through control of the chemical composition on a nanom eter scale, These possibilities are considered in the light of a numbe r of research projects being pursued at the Max Planck Institute for C ollid and Interface Research.