A Multiscale Modeling Protocol To Generate Realistic Polymer Surfaces

We present a multiscale modeling protocol to generate realistic amorphous polymer surfaces. Our computational approach consists of several steps having different levels of molecular detail. Initially, we generate a course-grained polymer surface that is completely relaxed using mesoscopic simulation methods. In the second step we transform the equilibrated coarse-grained polymer surface to atomistic detail with a special "mapper" that takes as input the mesoscopic morphology and uses Monte Carlo techniques to generate the atomistic structure. In the final step the atomistically detailed surface is equilibrated by performing a short molecular dynamics simulation. The great advantage of this multiscale approach is that it. allows the study of compounds that have intrinsically (very) slow equilibration dynamics such as polymers, which would be difficult to study with conventional simulation methods only. In addition, the multiscale approach makes it straightforward to "move" between different levels of molecular detail and even zoom in on a relevant part of the mesoscopic structure and map only that part. As test cases we applied the multiscale modeling protocol to polyethylene, polypropylene, and polyacrylonitrile.