Free-energy landscape of polymer-crystal polymorphism
Polymorphism rationalizes how processing can control the final structure of a material. The rugged free-energy landscape and exceedingly slow kinetics in the solid state have so far hampered computational investigations. We report for the first time the free-energy landscape of a polymorphic crystalline polymer, syndiotactic polystyrene. Coarse-grained metadynamics simulations allow us to efficiently sample the landscape at large. The free-energy difference between the two main polymorphs, α and β, is further investigated by quantum-chemical calculations. The results of the two methods are in line with experimental observations: they predict β as the more stable polymorph under standard conditions. Critically, the free-energy landscape suggests how the α polymorph may lead to experimentally observed kinetic traps. The combination of multiscale modeling, enhanced sampling, and quantum-chemical calculations offers an appealing strategy to uncover complex free-energy landscapes with polymorphic behavior.
This work reports for the first time the free-energy landscape of a polymorphic crystalline polymer, syndiotactic polystyrene, and suggests how the α polymorph may lead to experimentally observed kinetic traps.
@article{Liu_2020,
doi = {10.1039/d0sm01342k},
url = {https://doi.org/10.1039%2Fd0sm01342k},
year = 2020,
publisher = {Royal Society of Chemistry ({RSC})},
volume = {16},
number = {42},
pages = {9683--9692},
author = {Chan Liu and Jan Gerit Brandenburg and Omar Valsson and Kurt Kremer and Tristan Bereau},
title = {Free-energy landscape of polymer-crystal polymorphism},
journal = {Soft Matter}
}