Conductive Network Formation and Electrical Transport in Carbon‐Nanotube‐Filled Diblock Copolymers

We study the combined effects of microphase‐selective localization and aggregation of carbon nanotubes (CNTs) on conductive network formation and electrical conductivity in CNT‐filled, microphase‐separated diblock copolymers (DBCs) with a lamellar morphology. Using a phase‐field description of the DBC, we compute equilibrium order‐parameter profiles and derive the immersion energies of CNTs whose interaction with the DBC is characterized by an adhesion parameter . These immersion energies are incorporated into Monte Carlo simulations of CNTs in the DBC system, in which steric repulsion is combined with an effective Hamaker‐type attraction of strength to model CNT bundling. Aggregation of CNTs is quantified via the bundle‐size distribution , defined as the fraction of CNTs contained in bundles of size . Each simulated configuration is mapped onto a random resistor‐network model to compute the composite conductivity. We find that increasing drives CNTs into the selective microphase, lowering the percolation threshold and enhancing conductivity at fixed CNT load. In contrast, attractive CNT–CNT interactions () promote bundling, which suppresses conductivity at small filler concentrations. Overall, the results reveal a competition between localization‐controlled connectivity and interaction‐driven aggregation in determining electrical transport and suggest strategies to optimize conductivity by tuning the CNT–DBC adhesion and CNT–CNT cohesion.