Thermoelectric Behavior of Segregated-Network Polymer Nanocomposites

TLDR

The study demonstrates that polymeric thermoelectrics are feasible and lays groundwork for lightweight, low‑cost, nontoxic polymer composites for future thermoelectric applications. Segregated‑network CNT‑polymer composites were fabricated and tested, showing that thermally disconnected but electrically connected junctions allow tuning of electrical conductivity and thermoelectric figure of merit. Electrical conductivity increased dramatically with CNT network formation, while thermal conductivity and thermopower remained relatively unchanged; at 20 wt % CNT, composites achieved 4800 S/m conductivity, 0.34 W/m·K thermal conductivity, and ZT > 0.006, confirming the potential of polymeric thermoelectrics.

Abstract

Segregated-network carbon nanotube (CNT)-polymer composites were prepared, and their thermoelectric properties were measured as a function of CNT concentration at room temperature. This study shows that electrical conductivity can be dramatically increased by creating a network of CNTs in the composite, while the thermal conductivity and thermopower remain relatively insensitive to the filler concentration. This behavior results from thermally disconnected, but electrically connected, junctions in the nanotube network, which makes it feasible to tune the properties in favor of a higher thermoelectric figure of merit. With a CNT concentration of 20 wt %, these composites exhibit an electrical conductivity of 4800 S/m, thermal conductivity of 0.34 W/m x K and a thermoelectric figure of merit (ZT) greater than 0.006 at room temperature. This study suggests that polymeric thermoelectrics are possible and provides the basis for further development of lightweight, low-cost, and nontoxic polymer composites for thermoelectric applications in the future.