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Experimental Confirmation of Transformation Pathways between Inverse Double Diamond and Gyroid Cubic Phases
- Seddon, Annela
M., Hallett, James, Beddoes, Charlotte, Plivelic, Tomás S., Squires, Adam M.
- Langmuir 2014 v.30 no.20 pp. 5705-5710
- X-radiation, coatings, geometry, lipids, nanomaterials, osmotic stress, polyethylene glycol
- A macroscopically oriented double diamond inverse bicontinuous cubic phase (QIIᴰ) of the lipid glycerol monooleate is reversibly converted into a gyroid phase (QIIᴳ). The initial QIIᴰ phase is prepared in the form of a film coating the inside of a capillary, deposited under flow, which produces a sample uniaxially oriented with a ⟨110⟩ axis parallel to the symmetry axis of the sample. A transformation is induced by replacing the water within the capillary tube with a solution of poly(ethylene glycol), which draws water out of the QIIᴰ sample by osmotic stress. This converts the QIIᴰ phase into a QIIᴳ phase with two coexisting orientations, with the ⟨100⟩ and ⟨111⟩ axes parallel to the symmetry axis, as demonstrated by small-angle X-ray scattering. The process can then be reversed, to recover the initial orientation of QIIᴰ phase. The epitaxial relation between the two oriented mesophases is consistent with topology-preserving geometric pathways that have previously been hypothesized for the transformation. Furthermore, this has implications for the production of macroscopically oriented QIIᴳ phases, in particular with applications as nanomaterial templates.