The distinctive behavior of polyatomic structures such as colloidal particles, surfactant micelles, and polymer molecules in a liquid are reviewed. The qualitative differences between these forms of “soft matter” and small-molecule solids and liquids arise from their weak connectivity and entropic interactions. These effects produce spatial organization within one polyatomic structure and cooperative organization amongst many such structures. Such self-organization may arise in thermal equilibrium, from an irreversible growth process, or from flow. Conversely, the structures alter the transmission of forces in new ways. Potential benefits from the understanding of soft matter for electronic materials, for chemistry, and for biology are mentioned.

DOI:https://doi.org/10.1103/RevModPhys.71.S367