Domains of colloidal size, mediated by self-assembly of small molecules in a polymer matrix: a three-level hierarchy of assembly.

Studies on self-assembly of molecules, mediated by, e.g., hydrogen bonding interactions, are a major theme currently. The consequence of such self-assembly of hydrogen-bonding molecules, when dispersed in a polymer matrix, has not been studied so far. We describe such a polymer dispersed self-assembling small molecule system, in which a homologous series of small molecules, with a hydrogen-bonding moiety and alkyl side chains, is dispersed in polycarbonate. These are not liquid crystalline. The self-assembling molecules form colloidal size domains in the polymer, and this involves a hierarchy of three levels of assembly. The molecules self-assemble into small crystallites, which then organize into spherulitic structures. These spherulites then aggregate to form large, uniform near-spherical domains. The size and uniformity of the domains depend on the length of the alkyl side chain. The domain formation is reversible; that is, these domains can be melted and reformed.