Plasticizer for controlling single-walled carbon nanotube fibers and zincophilic sites of microfiber supercapacitor

In the past few decades, single-walled carbon nanotube (SWCNT) fibers have been considered for various applications, from aerospace to electronics including flexible devices. Here, we report an effective way of controlling the viscosity of the liquid crystal SWCNT phases for fiber spinning. By applying Tris(hydroxymethyl)aminomethane (THA)-functionalization to single-walled carbon nanotubes (SWCNT_CONH), we enhanced the free volume of individual SWCNTs, which synergistically affected the formation of nematic liquid crystal phases. As a result, we were able to precisely control the viscosity and phase transformation of the nematic liquid crystal phases for fiber spinning. The SWCNT fiber spun from those nematic phases with plasticizer (BP30CONH5; 30 mg/mL of SWCNT_BP with 5 wt% of SWCNT_CONH) exhibited noticeably higher mechanical properties (tensile strength, 1.44 GPa and tensile modulus, 169 GPa) with higher electrical conductivity (1899 S m(2)/kg). These fibers were also exceptionally flexible and showed endurable performance as wearable and flexible electronic electrode devices from well-distributed zincophilic sites (CONH). As an Zn-ion supercapacitor, the SWCNT fiber exhibited linear and volumetric capacitances of 14.33 mF cm(-1) and 22.55 F cm(-3) at 0.1 mA cm(-1) with capacitance retention of 98% after over 30 000 bending tests.

Automated summary

In this study, an effective method for controlling the viscosity of liquid crystal SWCNT phases was reported. By functionalizing single-walled carbon nanotubes, the viscosity and phase transformation of the liquid crystal phases could be precisely controlled. The resulting SWCNT fibers exhibited higher mechanical properties and electrical conductivity, as well as flexibility and durability for wearable and flexible electronic electrode devices. Moreover, the SWCNT fibers demonstrated excellent performance as Zn-ion supercapacitors with high capacitance retention after bending tests.