Search results for "Reptation"
showing 6 items of 16 documents
Computer simulation of macromolecular materials
1988
Computer simulation of model systems with Monte Carlo methods enables the detailed study of structure and thermodynamic properties of these systems and thus constitutes a link between analytic theory and experiment. Typical applications that are discussed include polymer blends, dynamics of local motions in polymer melts, and the adsorption of polymers on walls.
Anomalous diffusion in polymer melts
2002
Abstract We present a study of the anomalous diffusion regimes in polymer melt dynamics performing a Monte Carlo (MC) simulation of the bond-fluctuation lattice model. Special emphasis is laid on the crossover from a Rouse-like motion to the behavior predicted by reptation theory. For the longest chains of N=400 the high statistical accuracy of the data allows for clear identification of the subdiffusive regimes in the center of mass motion and the monomer displacement. They are well compatible with those predicted by reptation theory. Furthermore a detailed analysis of the different short time anomalous diffusion regimes in the melt dynamics of polymer chains is presented and it is shown t…
Static and dynamic scaling behavior of a polymer melt model with triple-well bending potential
2018
We perform molecular-dynamics simulations for polymer melts of the coarse-grained polyvinyl alcohol model that crystallizes upon slow cooling. To establish the properties of its high temperature liquid state as a reference point, we characterize in detail the structural features of equilibrated polymer melts with chain lengths $5\le N \le 1000$ at a temperature slightly above their crystallization temperature. We find that the conformations of sufficiently long polymers with $N >50$ obey essentially the Flory's ideality hypothesis. The chain length dependence of the end-to-end distance and the gyration radius follow the scaling predictions of ideal chains and the probability distributions o…
Polymer absorption in dense polymer brushes vs. polymer adsorption on the brush-solvent interface
2014
Molecular-dynamics simulations of a coarse-grained model of a dense brush of flexible polymers (of type A) interacting with a long flexible macromolecule (of type B) are presented, considering the case of an attractive AB interaction, while effective interactions between AA and BB pairs of monomers are repulsive. Varying the strength of the attraction between unlike monomers, an adsorption transition at some critical value is found, where the B-chain is bound to the brush-solvent interface, similar to the adsorption on a planar solid substrate. However, when is much higher than , the long macromolecule is gradually “sucked in” the brush, developing many pieces that are locally stretched in …
Monte-Carlo Simulation of 3-Dimensional Glassy Polymer Melts: Reptation Versus Single Monomer Dynamics
1995
A polymer melt is simulated at finite temperature by the Monte-Carlo method. We use a coarse-grained model for the polymer system, the bond-fluctuation model. Static properties of the melt can be obtained by generating configurations not with single-monomer- dynamics which moves individual monomers locally, but reptation-dynamics which allows collec- tive motion of the chains. This algorithm can produce equilibrated configurations much faster. It is demonstrated that static properties do not differ from those obtained by single-monomer- dynamics. Values of the radius of gyration, the mean square bond length and similar quantities for different temperatures and densities are presented.
Applications of “Forced Rayleigh Scattering” and “Photon Correlation Spectroscopy” for the examination of transport properties in polymer melts
2007
The importance of optical techniques for the characterization of the dynamics in polymers has increased in the last 10 years. This was caused by the rapid development in optics and microelectronics which has made these techniques easily available and extremely precise. However, in case of the examination of transport properties in bulk polymers, new difficulties arise due to the comparably slow dynamics underlying these phenomena. The topic of this paper is a small survey of two optical techniques which can be applied to solve the arising problems and a presentation of some results of our working group concerning slow translational transport processes in polymers. In a first part, the techn…