SWCNT Dispersion Liquid Using CMC for High-Concentration Stability

The patent introduces carboxymethyl cellulose as an intermediary substance between single-walled carbon nanotubes and water. This dispersant adsorbs onto the carbon nanotube surface through its carboxyl groups, forming a protective layer that prevents direct van der Waals interaction between nanotubes. The hydrophilic cellulose backbone extends into the aqueous phase, providing steric stabilization and enabling high-concentration dispersion (0.5-2.0 wt%) while maintaining stability. This mediator approach resolves the contradiction by allowing high concentration without sacrificing dispersibility.

The patent optimizes the molecular weight parameter of carboxymethyl cellulose to a specific range (10,000-1,000,000 g/mol, preferably 100,000-500,000 g/mol). This parameter optimization balances two opposing requirements: higher molecular weight provides better steric stabilization and dispersibility, while lower molecular weight ensures adequate fluidity and coating processability. By precisely controlling this parameter within the specified range, the patent achieves both dispersion stability and operational ease simultaneously.

The patent specifies a controlled degree of etherification range (0.5-1.2, preferably 0.6-1.0) for carboxymethyl cellulose. This parameter control is critical because the degree of etherification directly affects the balance between hydrophilicity (dispersibility) and molecular structure integrity. By maintaining the degree of etherification within this optimized range, the patent ensures sufficient hydrophilic character for good dispersibility while preserving the structural characteristics needed for predictable and controllable dispersion behavior during manufacturing.