Thermal conductivity of carbon nanotube-filled diblock copolymer composites

We investigate the influence of microphase-selective localization and aggregation of carbon nanotubes (CNTs) on the thermal conductivity of CNT-filled symmetric diblock copolymer (DBC) composites. A phase-field description of the DBC morphology is combined with Monte Carlo simulations of interacting CNTs and a thermal-resistance network model for heat transport. The simulations account for CNT-polymer affinity, steric exclusion, and attractive CNT-CNT interactions that promote bundling. The resulting CNT configurations are characterized in terms of localization, connectivity, and bundling. These configurations are subsequently mapped onto a thermal-resistance network that incorporates heat transport through both the CNT and polymer phases together with CNT-polymer interfacial resistance. We find that increasing the CNT-polymer affinity enhances CNT localization within the selective microphase and leads to a systematic increase in thermal conductivity. In contrast, stronger CNT-CNT attraction promotes bundling and generally reduces the efficiency of long-range heat transport. The results reveal a competition between localization-enhanced connectivity and attraction-induced aggregation of CNTs and identify the key mechanisms governing thermal transport in CNT-filled DBC nanocomposites.