showing 9 related works from this author
Ground states of ultrasoft particles with attractions: a genetic algorithm approach
2009
International audience; We analyze in detail the ground-state structure of model systems of athermal star polymers with an additional, tunable attraction that may result from dispersion or depletion forces. To perform a free, unbiased search in the space spanned by the crystal parameters, we employ genetic algorithms, which are enhanced with respect to previous versions in their ability to find stable structures that occupy very narrow basins of attraction in the energy landscape. Application of this method brings about a very large variety of ground states for star polymers with attractions, in particular for the case of intermediate functionalities and strong, short-range attractive force…
Interactions between polymer brush-coated spherical nanoparticles: the good solvent case.
2011
The interaction between two spherical polymer brushes is studied by molecular dynamics simulation varying both the radius of the spherical particles and their distance, as well as the grafting density and the chain length of the end-grafted flexible polymer chains. A coarse-grained bead-spring model is used to describe the macromolecules, and purely repulsive monomer-monomer interactions are taken throughout, restricting the study to the good solvent limit. Both the potential of mean force between the particles as a function of their distance is computed, for various choices of the parameters mentioned above, and the structural characteristics are discussed (density profiles, average end-to…
Spherical polymer brushes under good solvent conditions: molecular dynamics results compared to density functional theory.
2010
A coarse grained model for flexible polymers end-grafted to repulsive spherical nanoparticles is studied for various chain lengths and grafting densities under good solvent conditions, by Molecular Dynamics methods and density functional theory. With increasing chain length the monomer density profile exhibits a crossover to the star polymer limit. The distribution of polymer ends and the linear dimensions of individual polymer chains are obtained, while the inhomogeneous stretching of the chains is characterized by the local persistence lengths. The results on the structure factor of both single chain and full spherical brush as well as the range of applicability of the different theoretic…
Effect of the solvent quality on the structural rearrangement of spherical brushes: coarse-grained models
2012
A coarse-grained model for flexible polymers end-grafted to repulsive spherical nanoparticles is studied for various polymer lengths, grafting densities, and nanoparticle sizes by molecular dynamics simulations, considering variable solvent quality in the framework of an implicit solvent treatment. Below the theta point, the tuning of the temperature strongly influences the coverage of the nanoparticle surface by collapsed single chains or clusters of several chains. The shape and size of the aggregates depend on the number of monomers and surface density of the polymers. Specifically we analyzed the effect of the solvent quality on the density profiles and radius of gyration of the single …
Phase behavior of low-functionality, telechelic star block copolymers.
2010
We apply state-of-the-art, Grand Canonical Monte Carlo simulations to determine the self-organization and phase behavior of solutions of block copolymer stars. The latter consist of f AB-block copolymers with N monomers each, which contain a solvophilic block A and solvophobic block B, and which are tethered on a common center on their A-side. We vary the degree of polymerization N and the relative composition of the block copolymer arms and investigate the interplay between macrophase and microphase separation in the system. Preliminary results of the effect of increasing the number of arms, f of the stars are also presented.
Dynamics of macromolecules grafted in spherical brushes under good solvent conditions
2013
Spherical polymer brushes have a structure intermediate between star polymers and polymer brushes on flat substrates, and are important building blocks of polymer nanoparticles. Molecular dynamics simulations are presented for isolated spherical polymer brushes under good solvent conditions, varying the grafting density as well as the chain length, using a coarse-grained bead-spring model of flexible chains. We complement previous work on the static properties of the same model by analyzing the chain dynamics, studying the motions of monomers in relation to their position along the grafted chains, and extract suitable relaxation times. A qualitative discussion in terms of the Rouse model is…
Self-assembly scenarios of block copolymer stars
2011
We examine the self-organization scenarios of star-shaped AB-block copolymers, consisting of a solvophilic A-block and a solvophobic B-block, in which f such blocks are chemically anchored on a common centre on their A-parts, leaving the B-blocks exposed on their exterior. We employ a lattice model and we perform Grand Canonical Monte Carlo simulations for the case f = 6, varying thereby the percentage of attractive monomers as well as the concentration of stars. In agreement with previous studies on the low-functionality case f = 3 [F. Lo Verso, A.Z. Panagiotopoulos, and C.N. Likos, Phys. Rev. E 79, 010401(R) (2009)], we find that when the majority of monomers in the star are attractive, m…
Interaction Between Polymer Brush-Coated Spherical Nanoparticles: Effect of Solvent Quality
2012
The interaction between two spherical polymer brushes in solvents of variable quality is studied by molecular dynamics simulation and by self-consistent field theory, varying both the radius of the spherical particles and their distance, as well as the grafting density and the chain length of the end-grafted flexible polymer chains. Both the potential of mean force between the particles as a function of their distance is computed, for various choices of the parameters mentioned above, and the structural characteristics are discussed (density profiles, average end-to-end distance of grafted chains, etc.) It is found that for rather short chain lengths and not too large grafting densities, is…
Telechelic Star Polymers as Self-Assembling Units from the Molecular to the Macroscopic Scale
2012
By means of multiscale molecular simulations, we show that telechelic-star polymers are a simple, robust, and tunable system, which hierarchically self-assembles into soft-patchy particles and mechanically stabilizes selected, open crystalline structures. The self-aggregating patchy behavior can be fully controlled by the number of arms per star and by the fraction of attractive monomeric units at the free ends of the arms. Such self-assembled soft-patchy particles while forming, upon augmenting density, gel-like percolating networks, preserve properties as particle size, number, and arrangement of patches per particle. In particular, we demonstrate that the flexibility inherent in the soft…