Molecular dynamics simulation of the glass transition temperature of fullerene filled cis-1,4-polybutadiene nanocomposites

Abstract

In this work, the effect of the fullerene (C60) weight fraction and PB-C60 interaction on the glass transition temperature (T g) 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 T g could be affected by the C60 weight fraction due to its inhibition effect on the mobility of the cis-PB chains. However, T g is different, which depends on different dynamics scales. Among the chain dynamics properties, T g is the lowest from atom translational mobility, while it is the highest from the dynamic heterogeneity. In addition, T g can be more clearly distinguished from the dynamic heterogeneity; however, the conformational transition rate seems to be not very sensitive to the C60 weight fraction compared with others. For pure cis-PB chains, T g and 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 T g. The activation energy below T g is lower than that above T g. This work can help to understand the effect of the C60 on the dynamic properties and glass transition temperature of the cis-PB chains from different scales.