Coarse-grained model and force field development for predicting phase change and thermal transport in polyethylene

Coarse-grained model and force field for predicting phase change and thermal transport in meso-scale polyethylene were developed and its accuracy was validated. The coarse-grained force field was obtained through coarse-grained molecular dynamics simulations by multistate iterative Boltzmann inversion with all-atom molecular dynamics simulations as a benchmark. The simulations results show that the coarse-grained force field consisting of functional potential terms allows better transferability and more accurate description of the static structural properties of bulk polyethylene compared with those in all-atom simulations. Meanwhile, the deviations between values in coarse-grained simulations and experimental results of densities of bulk polyethylene at 300 K and 500 K are both within 3%. The values of glass transition temperature and melting temperature obtained from coarse-grained simulation are both close to experimental values. In addition, thermal conductivities of extended single polyethylene chain with various lengths in coarse-grained simulations match those in all-atom simulations well and thermal conductivity of disordered bulk polyethylene in coarse-grained simulation is close to the experimental value. The results provide a more powerful simulation method for the investigation of thermal conduction of meso-scale polyethylene.