title: Comment on "Discovery of a tetracontinuous, aqueous lyotropic network phase with unusual 3D-hexagonal symmetry" by M. Mahanthappa, G. Sorenson and A. Schmitt.
abstract: The article by Sorenson et al. (Soft Matter10, 8229, 2014) reports a novel phase formed by gemini surfactants in water, of symmetry P63/mcm and based on a triple intergrowth of three identical degree-three networks, known as 3etc(193). This phase is the first lyotropic liquid crystalline phase based on the intergrowth of a triplet of network- or labyrinth-like hydrophobic domains. We provide here results from self-consistent field theory that demonstrate that the same morphology is almost stable in standard AB diblock copolymer melts; at the phase transition between the double gyroid phase and the hexagonal columnar phase, the 3etc(193) morphology only incurs a marginal free energy penalty compared to the equilibrium phases. Interestingly, the ratio of lattice parameters c/a = 0.955 of the 3etc(193) as a diblock morphology is very close to that of the gemini surfactant phase and of the related IBN-9 mesoporous silicate phase (Han et al., Nat. Chem.1, 123, 2009). Based on the combination of these results, we hypothesise that the 3etc(193) morphology is likely a generic phase in soft materials, rather than an oddity.
authors.affiliation: Theoretische Physik, Friedrich-Alexander Universität Erlangen-Nürnberg, Staudtstr. 7B, 91058 Erlangen, Germany. gerd.schroeder-turk@fau.de.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fischer
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Hyde
authors.forename: Gerd E
authors.initials: GE
authors.lastname: Schröder-Turk