Self-assembly and mesophase formation in a non-ionic chromonic liquid crystal system: insights from dissipative particle dynamics simulations

Abstract

Results are presented from a dissipative particle dynamics (DPD) simulation of a model non-ionic chromonic system, TP6EO2M, composed of a poly(ethylene glycol) functionalised aromatic (triphenylene) core. The simulations demonstrate self-assembly of chromonic molecules to form single molecule stacks in solution at low concentrations, the formation of a nematic mesophase at higher concentrations and a columnar phase in the more concentrated regime. The simulation model used allows very large system sizes, of many thousands of particles, to be studied. This provides, for the first time, an opportunity to study chromonic phase behaviour by simulation without severe restrictions imposed by system size. In the low concentration limit, the simulations demonstrate approximate isodesmic association from which a binding energy can be obtained, allowing the simulations to be tuned to reproduce the behaviour of the real experimental system.

Molecular Simulation Studies of Cyanine‐Based Chromonic Mesogens: Spontaneous Symmetry Breaking to Form Chiral Aggregates and the Formation of a Novel Lamellar Structure

“…Here, it will be necessary to capture molecular structure and dimensions correctly, together with the correct free energy of association (as in Figure ). Candidates for these models include recent work on SAFT‐ γ and MARTINI models for chromonics, or dissipative particle dynamics (DPD) models, which may allow the study of competing modes of aggregation, counterion effects, and hierarchical self‐assembly.…”

Phase Behavior of Lipid Bilayers: A Dissipative Particle Dynamics Simulation Study

“…[20,21] Thereby, our understanding of the link between lipid molecular features and the corresponding phase behavior is far from complete. [30][31][32][33] Recently, a relatively new particle-based mesoscopic simulation technique known as dissipative particle dynamics (DPD) has been developed for the study of various complex fluids including polymers, [34][35][36][37][38] liquid crystals, [39][40][41] lipid membranes, [13,[42][43][44][45] vesicles, [12,[46][47][48][49] and even cells. [22][23][24][25][26][27] However, the idea resorted to atomistic molecular dynamics simulation method is unrealistic, since it is very time consuming for calculating phase diagrams and obtaining an overview of system behavior in a wide parameter range.…”

“…So far, considerable efforts have been devoted toward developing simplified generic coarse-grained (CG) models, in which each CG site represents a number of atoms, that is, either a part of a lipid molecule or a couple of water molecules [28,29] to systematically investigate the relation of lipid shape and size with membrane phase behavior. [30][31][32][33] Recently, a relatively new particle-based mesoscopic simulation technique known as dissipative particle dynamics (DPD) has been developed for the study of various complex fluids including polymers, [34][35][36][37][38] liquid crystals, [39][40][41] lipid membranes, [13,[42][43][44][45] vesicles, [12,[46][47][48][49] and even cells. [50] In DPD simulations, individual particle represents a cluster of atoms or molecules, interacts via soft potentials, and is subjected to dissipative and random forces that act together as a momentum conserving thermostat.…”

Simulation insights into the role of antiparallel molecular association in the formation of smectic A phases

“…Coupling the reduced degrees of freedom of a coarse grained simulation with a large time step has enabled simulation of a wide range of soft matter: block co-polymers, 34 , and this has been used to good effect in simulating polyphilic molecules such as bolaamphiphiles. [44][45][46][47][48] Here, we simulate preferred antiparallel molecular interactions by using two sites, B and C, which have a preferred B-C interaction. In DPD three simple forces act on the system: a conservative force, F C , a dissipative force, F D , and a random force, F R .…”