Coarse-Grained Polymer Melts Based on Isolated Atomistic Chains: Simulation of Polystyrene of Different Tacticities

Abstract

We present a molecular coarse-graining approach applied to polystyrene which obtains both the bonded and nonbonded interactions of the coarse-grained model from the sampling of isolated atomistic chains and pairs of oligomers. Atomistic melt properties are not used in the parametrization. We show that the coarse-grained polystyrene model not only predicts melt properties, including the melt packing and the density between 400 and 520 K, in satisfactory agreement with the atomistic model, but also reproduces the local chain conformations of atactic as well as stereoregular polystyrene. The model takes into account and reproduces correlations between neighboring bonded degrees of freedom and therefore reproduces the conformations of detailed atomistic chains in the melt on all length scales.

Molecular dynamics of polyisoprene/polystyrene oligomer blends: The role of self-concentration and fluctuations on blend dynamics

“…37 For PS the extracted value for the characteristic ratio is about 5.0, lower than the high molecular value of about 9.8 as reported in previous studies. 38 This value results to a Kuhn segment l k ≈ 7.65Å, for the PS oligomers studied here, smaller than the value of 15.0Å for high molecular weight PS. In previous works we have studied extensively the PS model predictions for structure, dimensions and dynamics of PS systems as a function of molecular weight.…”

Challenges in Multiscale Modeling of Polymer Dynamics

“…However, none of these methods can recover exactly the same dynamics of all-atomistic simulations. Harmandaris and Kremer [204,205,219,220] used short-chain atomistic and coarse-grained simulation to calculate a time-mapping constant based on the friction coefficients. In their approach, they assumed that the softer coarse-grained potential induces a reduced friction coefficient, ζ CG , between the super atoms.…”

Computer Simulations of Soft Matter: Linking the Scales

“…Understanding the physical nature of non-additivity in the system of interest can help to make a CG model transferable. In principle, there are various possibilities to approach the question of transferability of effective pair potentials: (i) One applies a model derived at/optimized for a given state point unaltered to a range of state points nearby; in that case, one has to carefully investigate the range in which this is permitted [144][145][146]; (ii) One creates a new set of potentials for each state point one wants to investigate [144]; (iii) One specifically designs a single CG model with the aim of transferability (for example specific density dependent potentials [94,147,148], CG models that are designed to be applicable for a range of mixture compositions [71,138], or CG models that are capable of capturing a liquid crystalline phase transition [88,89]); (iv) One uses a model derived at one state point and (analytically) modifies it to be applicable to different conditions (one example being the rescaling of potentials in order to apply them to a different temperature [149]). …”

“…In this field, structure-based models have been very successfully applied, and decent temperature [77,[150][151][152] and pressure transferability [153] have been found. In fact in the first papers by Tschöp et al [77,103] the temperature transferability already allowed the semi-quantitative prediction of shifts in Vogel Fulcher temperature for different polycarbonate modifications.…”