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, title={Free-energy landscape of polymer-crystal polymorphism}, volume={16}, ISSN={1744-6848}, url={http://dx.doi.org/10.1039/D0SM01342K}, DOI={10.1039/d0sm01342k}, number={42}, journal={Soft Matter}, publisher={Royal Society of Chemistry (RSC)}, author={Liu, Chan and Brandenburg, Jan Gerit and Valsson, Omar and Kremer, Kurt and Bereau, Tristan}, year={2020}, pages={9683–9692} }
