Alkyl chain positional isomers of dodecyl beta-D-glucoside: Thermotropic and lyotropic phase behavior and detergency

A series of six dodecyl glucopyranoside surfactants, each with a single glu copyranoside headgroup attached sequentially along the chain from carbon 1 to carbon 6, have been prepared in order to systematically simulate "branch ing" in glucose-based surfactants. The thermotropic and lyotropic liquid cr ystalline properties of the series have been investigated, as well as the h ard soil detergency of these surfactants. The introduction of "branching" i nto the alkyl chain strongly affects the packing of the molecules into crys tals and liquid crystalline structures, thereby influencing the thermotropi c properties and the surfactant/ water binary phase diagrams. Attachment of the headgroup at the terminal carbon or at carbon 2 does not appreciably i nfluence the surfactant behavior, while attachment at carbon 3, 4, 5, or 6 results in very different behavior from that of either 1 or 2. This discont inuous change is reflected in the detergency behavior of the surfactants an d can be attributed to the change in length and shape of the surfactant mol ecules and the subsequent changes in intermolecular interaction.