How Much Can We Coarse‐Grain while Retaining the Chemical Specificity? A Study of Sulfonated Poly(ether ether ketone)

Abstract

For mesoscale structural studies of polymers, obtaining maximum level of coarse‐graining that maintains the chemical specificity is highly desirable. Here we present a systematic coarse‐graining study of sulfonated poly(ether ether ketone), sPEEK, and show that a 71:3 coarse‐grained (CG) mapping is the maximum possible map within a CG bead‐spring model. We perform single chain atomistic simulation on the system to collect various structural distributions, against which the CG potentials are optimized using iterative Boltzmann inversion technique. The potentials thus extracted are shown to reproduce the target distributions for larger single chains as well as for multiple chains. The structure at the atomistic level is shown to be preserved when we back‐map the CG system to re‐introduce the atomistic details. By using the same CG mapping for another repeat unit sequence of sPEEK, we show that the nature of the effective interaction at the CG level depends strongly on the polymer sequence and cannot be assumed based on the nature of the corresponding atomistic unit. These CG potentials will be the key to future mesoscopic simulations to study the structure of sPEEK based polymer electrolyte membranes.

Toward Transferable Coarse‐Grained Potentials for Poly‐Aromatic Hydrocarbons: A Force Matching Approach

“…The atomistic level information is retrieved by reintroducing the atomistic details on to an equilibrated CG structure, aptly called back‐mapping. Usually, a small MD run suffices in equilibrating such a back‐mapped configuration, and therefore, back‐mapping can accelerate equilibration of large atomistic systems …”

Molecular Structuring and Percolation Transition in Hydrated Sulfonated Poly(ether ether ketone) Membranes

“…In our earlier work on systematic coarse-graining of sPEEK 25 , we developed a model, with the highest possible coarse-grained (CG) mapping, for a 50% sulfonated sPEEK with alternate sulfonated units (Figure 1).…”

“…The corresponding equilibrated atomistic trajectory was easily obtained upon back-mapping, wherein a pre-equilibrated atomistic chain is mapped onto an equilibrated CG configuration of a comparatively larger system size, followed by short Molecular Dynamics (MD) run. Further details on the coarse-graining methodology, CG potentials, and backmapping can be obtained in the original reference 25 .…”

“…Though achieving larger length scales in atomistic simulation is nonetheless possible, it is computationally expensive and calls for sophisticated modeling approach and computing resource 23,24 . In the work presented here, we use a systematic coarse-graining method developed by us 25 to access the atomistic configurations with large system sizes.…”

Pre‐Oxidized Acrylic Fiber Reinforced Ferric Sulfophenyl Phosphate‐Doped Polybenzimidazole‐Based High‐Temperature Proton Exchange Membrane

“…Nafion and its fluorinated analogues were developed and doped with hygroscopic species or proton conductors to improve its performance at low hydration levels. Sulfonated heat‐resistant polymers such as sulfonated poly(aryl ether ketone) family and sulfonated polyimide were also developed and incorporated with inorganic proton‐conductive nanoparticles in the preparation of high‐temperature proton exchange membranes (PEMs). Organic–inorganic hybrid membranes and acid–base blend membranes were prepared for high‐temperature PEMFC applications .…”