Self-Assembly of Ternary Cubic, Hexagonal, and Lamellar Mesophases Using the Lattice-Boltzmann Kinetic Method

Abstract

We use a kinetic lattice-Boltzmann method to simulate the self-assembly of the cubic primitive (P), diamond (D), and gyroid (G) mesophases from an initial quench composed of oil, water, and amphiphilic particles. Here, we also report the self-assembly of the noncubic hexagonal phase and two lamellar phases, one with periodic convolutions. The periodic mesophase structures are emergent from the underlying conservation laws and quasi-molecular interactions of the lattice-Boltzmann model. We locate regions of the model's parameter space where the sequence of appearance of mesophases lamellar --> primitive --> hexagonal is in agreement with pressure jump experiments and the sequence cubic --> lamellar is in agreement with compositional variations reported in the literature. The ability of our lattice-Boltzmann model to simulate self-assembly of cubic and noncubic phases in a unified and consistent manner opens the way for further investigations into the transition pathways and kinetics of the phase transitions between these states as well as of the rheology of these phases.

Virtualizing access to scientific applications with the Application Hosting Environment

“…We anticipate that the new virtual machine based release mechanism will significantly increase that number. AHE has been used to host a wide variety of computational codes from many different scientific domains, including widely used codes such as NAMD [80], CHARMM [81], LAMMPS [82], VASP [83], DL_POLY [84], HemeLB [74] and LB3D [85]. The key strength of AHE is its flexibility.…”

Numerical simulations of complex fluid-fluid interface dynamics

“…By adjusting temperature, fluid composition or pressure, the amphiphiles can self-assemble and force the fluid mixture into a number of equilibrium structures or mesophases. These include lamellae and hexagonally packed cylinders, micellar, primitive, diamond, or gyroid cubic mesophases as well as sponge phases [66]. The latter are generally not well ordered, but might have a well defined average size of fluid domains.…”

Real science at the petascale

“…The distribution of defects within a liquid crystal domain, defined as the 'texture' of the liquid crystal, plays a significant role in its rheology (Rey & Denn 2002). Kinetic LB simulations on smaller 64 3 lattice sites lead to self-assembled monodomains of perfect gyroid, diamond and primitive mesophases (Saksena & Coveney 2008a), while real-world liquid crystalline mesophases usually do not exist as monocrystals but rather as multiple oriented grains with grain boundary defects as well as dislocations and defects within the grains. Investigation of the rheology of these defect-containing multi-domain systems requires simulation of larger lattices, ideally comprising 256 3 lattice sites or more.…”

“…Future work in this area will focus on following temporal defect dynamics that involves extremely disk-intensive analysis; scaling of disk I/O will become a major factor in determining code performance as we run simulations on higher and higher core counts. We plan to extend this work to other liquid crystalline phases such as the primitive and diamond phases (Saksena & Coveney 2008a). …”