Field-tuned CNT alignment and frequency dependence of electrical properties of CNT based nanocomposites

• CNT alignment can be tailored inside the liquid matrix by external electric fields. • Composites have higher electrical conductivity and lower percolation threshold. • A CNT polarization kinetic model and a homogenization scheme are built. • A coated-CNT model is built to analyze frequency-dependent interfacial effects. • Three independent experimental validation confirms the model's accuracy. Carbon nanotube (CNT)-based nanocomposites exhibit exceptional electrical tunability under external electric fields, while the dynamics of field-driven CNT alignment and its impact on transverse isotropy of the overall composite remain underexplored. This study establishes a unified micro-mesoscale framework to decode the electro-structural evolution of CNT-polymer composites. We integrate an overdamped rotational kinetics model for CNT reorientation with an effective-medium homogenization scheme, incorporating interfacial electron tunneling, electron hopping, and dielectric relaxation. Our theory quantifies how electric field parameters (strength, frequency, and duration) govern CNT alignment-characterized by a maximum distribution angle-and subsequently modulate the composite's effective electrical conductivity and dielectric permittivity. Validated against three independent experiments, this work provides insights into the alignment dynamics of CNTs, the evolution of percolation thresholds, and the field-tuned electrical behaviors of composites. The modeling and theory are crucial for the design and optimization of CNT nanocomposites for flexible electronics, energy storage, and field-responsive smart materials.