5 research outputs found
Dissipative particle dynamics study of solvent mediated transitions in pores decorated with tethered polymer brushes in the form of stripes
We study self-assembly of a binary mixture of components A and B confined in
a slit-like pore with the walls modified by the stripes of tethered brushes
made of beads of a sort A. The emphasis is on solvent mediated transitions
between morphologies when the composition of the mixture varies. For certain
limiting cases of the pore geometry we found that an effective reduction of the
dimensionality may lead to a quasi one- and two-dimensional demixing. The
change of the environment for the chains upon changing the composition of the
mixture from polymer melt to a good solvent conditions provides explanation for
the mechanism of development of several solvent mediated morphologies and, in
some cases, for switching between them. We found solvent mediated lamellar,
meander and in-lined cylinder phases. Quantitative analysis of morphology
structure is performed considering brush overlap integrals and gyration tensor
components.Comment: 14 pages, 12 figure
Nematic-isotropic transition in a weakly diluted lattice model: Monte Carlo study
We consider a weakly diluted lattice model of elongated particles undergoing a first order nematic-isotropic transition in a pure bulk case. The lattice of 20 3 sites with a 5% dilution is studied by Monte Carlo simulation and by applying the Ferrenberg-Swendsen histogram technique. The shift of the transition temperature and the decrease of the latent heat and the order parameter due to dilution are calculated. The heat capacity and the susceptibility peaks are essentially suppressed as compared to a pure case. The comparison to the experiments on liquid crystals confined in silica aerogels and porous glasses is done
COMPUTER SIMULATION STUDY OF A NEMATOGENIC LATTICE-GAS MODEL BASED ON THE NEHRING–SAUPE INTERACTION POTENTIAL
Nematic-isotropic transition in a lattice model with quenched disordered impurities: A Monte Carlo study
First-principle-based MD description of azobenzene molecular rods
Extensive density functional theory (DFT) calculations have been performed to develop a force field for the classical molecular dynamics (MD) simulations of various azobenzene derivatives. Besides azobenzene, we focused on a thiolated azobenzene’s molecular rod (4′-{[(1,1′-biphenyl)-4-yl]diazenyl}-(1,1′-biphenyl)-4-thiol) that has been previously demonstrated to photoisomerize from trans to cis with high yields on surfaces. The developed force field is an extension of OPLS All Atoms, and key bonding parameters are parameterized to reproduce the potential energy profiles calculated by DFT. For each of the parameterized molecule, we propose three sets of parameters: one best suited for the trans configuration, one for the cis configuration, and finally, a set able to describe both at a satisfactory degree. The quality of the derived parameters is evaluated by comparing with structural and vibrational experimental data. The developed force field opens the way to the classical MD simulations of self-assembled monolayers (SAMs) of azobenzene’s molecular rods, as well as to the quantum mechanics/molecular mechanics study of photoisomerization in SAMs