Self-Assembled Morphologies and Percolation Probability of Mixed Carbon Fillers in the Diblock Copolymer Template: Hybrid Particle-Field Molecular Dynamics Simulation

The self-assembly of polymer composites of mixed carbon fillers including single-walled carbon nanotube (SWCNT) and carbon black nanoparticles (CB NPs) in diblock copolymer (BCP) template are investigated using hybrid particle-field molecular dynamics simulations in this work. Simulations show, in agreement with experiments, that composites of BCP template with SWCNT have lower percolation threshold than that of BCP template with CB NPs. Moreover, the ratio between SWCNT and CB NPs has a strong influence on the percolation threshold of composites. The results of percolation probability show that adding more SWCNT (compared with CB NPs) to the BCP template could decrease the percolation threshold. However, a synergistic effect of percolation of the mixed carbon fillers in BCP template has been found. In particular, a nonlinear relation following the Boltzman function has been found, and the lowest percolation threshold exists with the volume ratio 4:1 (SWCNT/CB NPs) compared with the volume ratios of 1:1, 2:1, and 8:1 (SWCNT/CB NPs). The mixed carbon fillers also affect the morphologies of the BCP template, and the calculated radius of gyration of BCP shows that, in a higher concentration of the mixed fillers, the stretching of BCP is stronger, which results in the deformation of BCP template.