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.