0000000000371275
AUTHOR
T. Strauch
Phase transitions of single polymer chains and of polymer solutions: insights from Monte Carlo simulations
The statistical mechanics of flexible and semiflexible macromolecules is distinct from that of small molecule systems, since the thermodynamic limit can also be approached when the number of (effective) monomers of a single chain (realizable by a polymer solution in the dilute limit) is approaching infinity. One can introduce effective attractive interactions into a simulation model for a single chain such that a swollen coil contracts when the temperature is reduced, until excluded volume interactions are effectively canceled by attractive forces, and the chain conformation becomes almost Gaussian at the theta point. This state corresponds to a tricritical point, as the renormalization gro…
Phase transitions in a single polymer chain: A micro-canonical analysis of Wang–Landau simulations
Abstract We present simulation results for the phase behavior of a single chain for a flexible lattice polymer model using the Wang–Landau sampling idea. Using the micro-canonical density of states obtained with this method we will discuss the ability of an analysis in the micro-canonical ensemble to locate the coil-globule (continuous) and liquid–solid (first-order) transitions found for this problem using a canonical analysis.
Unexpectedly normal phase behavior of single homopolymer chains
Employing Monte Carlo simulations, we show that the topology of the phase diagram of a single flexible homopolymer chain changes in dependence on the range of an attractive square well interaction between the monomers. For a range of attraction larger than a critical value, the equilibrium phase diagram of the single polymer chain and the corresponding polymer solution phase diagram exhibit vapor (swollen coil, dilute solution), liquid (collapsed globule, dense solution), and solid phases. Otherwise, the liquid-vapor transition vanishes from the equilibrium phase diagram for both the single chain and the polymer solution. This change in topology of the phase diagram resembles the behavior k…
A coarse-graining procedure for polymer melts applied to 1,4-polybutadiene
We present a coarse-graining procedure for homopolymer melts mapping intra- as well as inter-molecular interactions from a chemically realistic united atom description to a bead-spring type molecular model. On the coarse-grained level the repeat units interact through bond-length and bond angle potentials and a non-bonded Lennard-Jones type interaction. The latter one is of the 7,4 form and softer than the typically employed 12,6 interactions. The coarse-graining of the intramolecular interactions follows well developed procedures, however, we point out in which way the non-bonded intramolecular interactions in the chemically realistic model should be treated. The parameters of the non-bond…