Bisphenol A Polycarbonate:  Entanglement Analysis from Coarse-Grained MD Simulations

Abstract

Simulation data are presented for a coarse-grained model of polycarbonate (BPA-PC), which allow for a detailed comparison of different ways to study the chain dynamics and predict the entanglement molecular weight. Most of the standard experimental quantities are determined for the very same set of systems and thus provide an opportunity for a detailed comparison of data far beyond typical experiments or simulations. By employing a suitably coarse-grained model, which still contains the essentials of the BPA-PC structure, simulation times compared to atomistic simulations could be extended by several orders of magnitude, reaching well into the characteristic experimental regime. We find that a recently developed topological entanglement analysis compares well with a direct determination of the modulus from simulations as with experiments on well-characterized samples. This confirms the extraordinarily small value of the entanglement molecular weight on Me between 1200 and 1400 corresponding to Ne close to 5.

Polymer Dynamics: Long Time Simulations and Topological Constraints

“…Figure ?? shows this, again for the example of polycarbonates [16]. From the above expression d T can be estimated.…”

“…[17,24] ( ) and a semi-atomistic polycarbonate melt [16] (♦) under an elongational strain, and (iii) predictions of the tube model Eq. 6 based on the results of our PPA for bead-spring melts ( ), and the semiatomistic polycarbonate melt ( ).…”

“…The best fit for the entanglement length yields n e = 62±8 coarse grained beads, giving approximately N e,D 15. Figure taken from [16] …”

“…1. For the present case of the diffusion of polycarbonate, the master curve is from experiments on polyethylene [16]. This allows for a first determination of N e and thus d T .…”

“…[29]. In addition, we present results for a coarse-grained model for polycarbonate (BPA-PC) [16,30]. In this case, we analyzed melt configurations for M = 100 chains of N = 60 chemical repeat units which are represented by four beads each.…”