Development of an <i>All-Atom</i> Force Field for the Simulation of Liquid Crystal Molecules in Condensed Phases (LCFF)

Cook, Melanie J.; Wilson, Mark R.

doi:10.1080/10587250108028250

Cited by 7 publications

(1 citation statement)

References 34 publications

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“…We chose GAFF because it has been parameterized for use with organic molecules. Although researchers have optimized force fields, including GAFF, for use with liquid crystals, they are often tuned in order to reproduce one or more experimental observables for specific types of liquid crystal molecules. , Na-GA3C11 does not have a structure characteristic of more commonly studied liquid crystal monomers, so we chose to stick with a widely used force field. If we can reproduce experimental trends using a single “out-of-the-box” force field, then there will be no need to complicate our studies with customized parameter sets.…”

Section: Methodsmentioning

confidence: 99%

Understanding the Nanoscale Structure of Inverted Hexagonal Phase Lyotropic Liquid Crystal Polymer Membranes

Coscia¹,

Yelk²,

Glaser³

et al. 2018

J. Phys. Chem. B

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Periodic, nanostructured porous polymer membranes made from the cross-linked inverted hexagonal phase of self-assembled lyotropic liquid crystals (LLCs) are a promising class of materials for selective separations. In this work, we investigate an experimentally characterized LLC polymer membrane using atomistic molecular modeling. In particular, we compare simulated X-ray diffraction (XRD) patterns with experimental XRD data to quantify and understand the differences between simulation and experiment. We find that the nanopores are likely composed of five columns of stacked LLC monomers which surround each hydrophilic core. Evidence suggests that these columns likely move independently of each other over longer time scales than accessible via atomistic simulation. We also find that wide-angle X-ray scattering structural features previously attributed to monomer tail tilt are likely instead due to ordered tail packing. Although this system has been reported as dry, we show that small amounts of water are necessary to reproduce all features from the experimental XRD pattern because of asymmetries introduced by hydrogen bonds between the monomer head groups and water molecules. Finally, we explore the composition and structure of the nanopores and reveal that there exists a composition gradient rather than an abrupt partition between the hydrophilic and hydrophobic regions. A caveat is that the time scales of the dynamics are extremely long for this system, resulting in simulated structures that appear too ordered, thus requiring careful examination of the metastable states observed in order to draw any conclusions. The clear picture of the nanoscopic structure of these membranes provided in this study will enable a better understanding of the mechanisms of small-molecule transport within these nanopores.

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Section: Methodsmentioning

confidence: 99%

Understanding the Nanoscale Structure of Inverted Hexagonal Phase Lyotropic Liquid Crystal Polymer Membranes

Coscia¹,

Yelk²,

Glaser³

et al. 2018

J. Phys. Chem. B

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Towards in Silico Liquid Crystals. Realistic Transition Temperatures and Physical Properties for n‐Cyanobiphenyls via Molecular Dynamics Simulations

et al. 2009

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We study the important n-cyanobiphenyl (with n= 4-8) series of mesogens, using modelling and molecular dynamics simulations. We are able to obtain spontaneously ordered nematics upon cooling isotropic samples of 250 molecules. By using the united-atom force field developed herein, we show that the experimental isotropic-nematic transition temperatures are reproduced within 4 K, allowing a molecular-level interpretation of the odd-even effect along the series. Other properties, like densities, orientational order parameters and NMR residual dipolar couplings are also reproduced well, demonstrating the feasibility of predictive in silico modelling of nematics from the molecular structure.

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Wilson

Earl

2001

J. Mater. Chem.

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Development of an All-Atom Force Field for the Simulation of Liquid Crystal Molecules in Condensed Phases (LCFF)

Cited by 7 publications

References 34 publications

Understanding the Nanoscale Structure of Inverted Hexagonal Phase Lyotropic Liquid Crystal Polymer Membranes

Understanding the Nanoscale Structure of Inverted Hexagonal Phase Lyotropic Liquid Crystal Polymer Membranes

Towards in Silico Liquid Crystals. Realistic Transition Temperatures and Physical Properties for n‐Cyanobiphenyls via Molecular Dynamics Simulations

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