This article is concerned with the structure and dynamic properties of thin films that have been chemically stabilized by polymerization and cross-linking reactions. By using different types of monomers it is possible to construct networks with rubber-like elasticity or with glassy properties, or temporary networks, in the interfacial region between oil and water. The systematic study of these ultrathin membranes offers new insights into aspects of current research, and opens up a wide range of potential new applications.