In Situ Interfacial Polymerization: A Technique for Rapid Formation of Highly Loaded Carbon Nanotube‐Polymer Composites

Abstract Composites of polymers and organized carbon nanotube (CNT) networks have been proposed as next‐generation lightweight structural materials, yet polymer infiltration of CNT networks often results in stress‐concentrating heterogeneities, due to local CNT aggregation or incomplete infiltration. Herein, it is demonstrated that dense CNT‐polymer composites with tailored polymer distribution can be obtained by interfacial polymerization (IP), performed in situ within CNT networks. Three regimes of the in situ interfacial polymerization (ISIP) process are identified: a reaction‐limited regime where the polymer forms beads on the CNTs; a uniformly‐filled regime with polymer throughout the CNT network; and a transport‐limited regime with polymer only near the outer surface of the network. Uniform polyamide‐CNT composite sheets obtained by this method have a Young's modulus of 31 GPa and a tensile strength of 776 MPa, which is a two‐fold increase compared to the pristine CNT sheets. Premature failure of the composites is attributed to large voids in the pristine CNT sheets, suggesting that further improved mechanical properties can be achieved with a more homogeneous CNT network. Nevertheless, the rapid rate and overall controllability of ISIP suggest its viability for formation of polymers within CNT networks via roll‐to‐roll methods.