Polyaniline (PANI) was prepared by in-situ polymerization and compounded on the two-dimensional network structural multi-walled carbon nanotube film (CNTF). Compared with the CNT/PANI composites fabricated by using CNT powders or dispersions, the compact and continuous network structure of CNTF/PANI is beneficial to both the thermoelectric and mechanical properties of the composites. The resultant CNTF/PANI composites with PANI polymerization time of 5 h obtain an electrical conductivity of 1338.4 S/cm and Seebeck coefficient of 63.3 μV/K at 360 K, which are 168.7% and 5.7% higher than those of the CNTF (498.1 S/cm and 59.9 μV/K at 360 K). Consequently, a maximum power factor of 536.8 μW·m⁻¹·K⁻² at 360 K is acquired, which is about 2 times higher than that of CNTF (181.7 μW·m⁻¹·K⁻² at 360 K). The electrical conductivity of the composites could maintain 93.3% after being bent for 500 times, indicating the excellent flexibility. The tensile strength, Young's Modulus and toughness of CNTF/PANI composites (232.3 MPa, 3.6 GPa and 20.1 MJ/m³, respectively) are 3.5, 2.6 and 2.1 times of those of the CNTF. The flexible, free-standing, lightweight and high-strength CNTF/PANI composites reveal the excellent thermoelectric performance, which are promising in the applications in wearable thermoelectric devices.

Carbon nanotube film (CNTF) with two-dimensional CNT network structure is adopted to prepare CNTF/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thermoelectric composites, which overcomes the disadvantages of low content, easy aggregation, and random orientation of CNTs when dispersed in polymer. A vacuum-assisted filtration method was proposed, which can uniformly and sufficiently penetrate the polymer into CNTF along thickness direction for fabrication of CNTF/PEDOT:PSS composites. A highest electrical conductivity of 806.2 S/cm at 300 K was achieved for the composites with 60 wt% PEDOT:PSS loading, which was 51.0% higher than that of the original CNTF (534.1 S/cm). A maximum power factor of 339.6 μW·m⁻¹·K⁻² at 320 K was achieved with a corresponding Seebeck coefficient of 67.7 μV/K. This study provides a universal method for fabrication of other kinds of CNTF/conductive polymer thermoelectric composites.