Structural organization and phase behaviour of meta-substituted dioctadecylaminobenzoquinones at the air/water interfaceElectronic supplementary information (ESI) available: Experimental details of Langmuir monolayer film preparation and Brewster angle microscopy at the air/water interface, GIXD experimental conditions, multiple compression-expansion cycles, maxima of Bragg peak and Bragg rod fits of the GIXD measurements. See DOI: 10.1039/c8cp07186a

The structural organization and phase behaviour of an amphiphilic zwitterionic quinonemonoimine at the air/water interface are presented. Brewster angle microscopy reveals multiple co-existing phases are observed over the entire isotherm while grazing incidence X-ray diffraction (GIXD) shows that these comprise both tilted, untilted and multilayer structures with crystalline headgroups. Despite the heterogeneity, the phase transitions are highly reversible over multiple cycles. A Langmuir monolayer formed from a zwitterionic lipid analogue that exhibits a highly reversible transition to a three-dimensional multilayer structure driven by headgroup crystallization.