023. Molecular-weight dependence of simulated glass transition temperature for isolated poly(ethylene oxide) chain
writer：Chaofu Wu
keywords：Glass transition temperatures; isolated polymer chains; confinement effects; multiscale simulations
source：期刊
specific source：Molecular Simulation 2020; 46(10): 727-735
Issue time：2020年
Molecular dynamics simulations have been performed with chemically realistic coarse-grained potentials to assess the effects of molecular weight on the glass transition temperatures (Tg) of single-chain particle of poly(ethylene oxide) in a vacuum. It is found that all the long isolated chains form impact globule like configurations, and higher molecular weight and lower temperature lead to more perfect sphericity. With increasing molecular weight, the simulated Tg of the isolated chain tends to increase whereas the Tg of the bulk undergoes a slight change. The confinement effects are associated with localisation of chain ends at the surface and specific surface areas. More importantly, the Tg shift can be quantified by the solubility parameter that includes the contribution of conformational change. As compared to the conventional definition that only sums intermolecular interactions, such solubility parameter is a better metric in simulations to explain the confinement effects since it does not depend upon the degree of equilibration as the Tg. These results can be quite valuable to clarifying glass transition behaviour of polymers films.
https://www.tandfonline.com/doi/full/10.1080/08927022.2020.1763986