Lipids are biological surfactants that self-assemble in aqueous media to form repeating structures in 1, 2 or 3 dimensions, driven by the propensity of the lipid molecules to pack such that hydrophobic moieties are protected from contact with water, whilst accommodating the geometric packing requirements imposed by the 'shape' of the individual lipid molecules. As fundamental components of the biological membrane, lipids and their mesoscale structures have informed our understanding of the structure and activity of the bilayers in which they reside, and have been used extensively as the basis of 'bottom-up' bioinspired systems. The most structurally exotic of these lyotropic lipid phases are the bicontinuous cubic phases, in which a bilayer separates two interconnecting water channels, and can adopt geometries that are based on the "diamond" (𝑄 𝐼𝐼 𝐷 ), the "primitive" (𝑄 𝐼𝐼 𝑃 ) and the "gyroid" (𝑄 𝐼𝐼 𝐺 ) minimal surfaces, with crystallographic space groups Pn3m, Im3m and Ia3d respectively (Figure ). Their ability to form a 3-dimensional array that incorporates the bilayer motif has led to their application as matrices for the crystallization of membrane proteins, 2-3 templating, and biosensing to name a few. In addition, cubic phases are candidates for engineered drug delivery systems due to their mesoporous structure, where biologically active contents can be encapsulated and later released in a controlled manner. Figure : From left to right: Structures of the 𝑄 𝐼𝐼 𝐺 , 𝑄 𝐼𝐼 𝐷 and 𝑄 𝐼𝐼 𝑃 phases. Top: Skeletal graphs representing the water channel networks. Bottom: Skeletal graphs and surfaces that approximate the underlying minimal surfaces. One unit cell of each structure is shown for the 𝑄 𝐼𝐼 𝐺 and 𝑄 𝐼𝐼 𝑃 phases and eight for the 𝑄 𝐼𝐼 𝐷 . The two sides of the surface have been shaded differently for clarity, although in reality they are identical. Reproduced with permission from While most research on QII phases has been carried out on bulk gels or dispersed nanoparticles in solution there has very recently emerged an interest in their study as thin films or coatings on solid substrates. This interest is in part motivated by opportunities to study QII phases using techniques such as GI-SAXS, AFM and voltammetry , where the high degree of surface orientation gives insights into interfacial structure and energetics. Furthermore, supported QII phase films provide a route to new functional (bio)materials. QII phase films are stable under water or in humidified air, and have been investigated for several very different applications: as electrochemical sensors; for delivery of bio-active agents; and as structure-directing templates, for the growth of nanostructured metals semiconductors and silica. Most of the studies of QII phase films has involved the gyroid (𝑄 𝐼𝐼 𝐺 ) or diamond (𝑄 𝐼𝐼 𝐷 ) phases, which are by far the most commonly observed for binary lipid / water systems. The films display high degrees of orientation, as demonstrated by GI-SAXS. The 𝑄 𝐼𝐼 𝐷 phase aligns with the [111] direction perpendicular to the substrate. The 𝑄 𝐼𝐼 𝐺 phase usually shows [110] alignment although the [211] orientation has also been observed; it is likely that this reflects differences in relative surface energies arising from the hydrophobicity of the substrate materials used in the various studies. Significantly, the orientation of the QII phase film is then transferred to the nanomaterial films deposited within it. 17, 20 Furthermore, the orientation adopted can be rationalized by a thermodynamic model that minimizes the bending energy associated with a continuous bilayer at the cubic phase surface, which we demonstrate here. Taken together, this suggests a rational and robust approach to the production of oriented nanomaterial films.