Molecular Dynamics Simulation of the Glass Transition Temperature of Fullerene Filled Cis-1,4-polybutadiene Nanocomposites

In this work, the effect of the fullerene(C60) weight fraction and PB-C60interaction on the glass transition temperature(Tg) of polymer chains has been systemically investigated by adopting the united atom model of cis-1,4-poly(butadiene)(cis-PB). Various chain dynamics properties, such as atom translational mobility, bond/segment reorientation dynamics, torsional dynamics, conformational transition rate and dynamic heterogeneity of the cis-PB chains, are analyzed in detail. It is found that Tgcould be affected by the C60weight fraction due to its inhibition effect on the mobility of the cis-PB chains. However, Tgis different, which depends on different dynamics scales. Among the chain dynamics properties, Tgis the lowest from atom translational mobility, while it is the highest from the dynamic heterogeneity. In addition, Tgcan be more clearly distinguished from the dynamic heterogeneity; however, the conformational transition rate seems to be not very sensitive to the C60weight fraction compared with others. For pure cis-PB chains, Tgand the activation energy in this work can be compared with those of other polymers. In addition, the temperature dependence of the dynamic properties has different Arrhenius behaviors above and below Tg. The activation energy below Tgis lower than that above Tg. This work can help to understand the effect of the C60on the dynamic properties and glass transition temperature of the cis-PB chains from different scales.