Cellulose-Reinforced Carbon Nanotube Buckypapers with Balanced Mechanical Strength and Conductivity

Buckypaper (BP), a self-supporting conductive thin film made from carbon nanotubes, is known for its ease of manufacture, excellent repeatability, and promising potential in the electronics field. However, challenges remain in balancing its mechanical strength and conductivity. In this study, we present a simple and effective one-pot synthesis method to fabricate highly conductive and mechanically robust BPs composed of a conjugated polymer (P1)-single-walled carbon nanotube (SWNT) complex and microcrystalline cellulose (MCC). P1, which features a self-immolative linker (SIL) between the polymer backbone and side chain, is used to disperse SWNTs in organic solvents. Upon treatment with tetra-n-butylammonium fluoride (TBAF), the insulating side chains of the polymer are removed to yield P0, which significantly enhances the conductivity of the resulting BP. However, this side chain removal weakens the mechanical strength of the BP. To address this trade-off, MCC was introduced as a mechanical reinforcing agent. Leveraging the good solubility of MCC in a TBAF/DMSO mixture, we developed a one-pot synthesis method to fabricate composite BPs with P0-SWNT complexes and MCC, using TBAF for both solubilization and side chain removal. The composite BPs exhibited improved mechanical properties and conductivity. Notably, a BP containing 42% P0-SWNT by weight demonstrated an optimal balance of strength (tensile modulus of 161 ± 10 MPa, yield point of 11 ± 2%) and conductivity (107 ± 4 S/m). This straightforward and scalable preparation method allows production of BPs with balanced mechanical and electrical properties that may be valuable for downstream applications.