Poly(tannin urethane)-Stabilized Multiwalled Carbon Nanotube Aqueous Dispersion for Antistatic Coating

The individually dispersed multiwalled carbon nanotubes (MWCNTs) enable the comprehensive accomplishment of intrinsic electrical conductivity, thermal conductivity, and antielectromagnetic shielding characteristics. However, the design of an aqueous carbon nanotube (CNT) dispersant remains a significant challenge in rational balances of strong interfacial interactions between CNT/dispersant and water medium. In the current research, biomass tannic acid (TA) was selected as the building block to synthesize poly(tannin urethane) (PTU) by step polymerization of TA and toluene diisocyanate, which was examined as a novel dispersant for MWCNTs. A highly homogeneous dispersion of PTU-stabilized MWCNTs and carbon black (CB) was prepared by a simple sonification and homogenization process to form aqueous antistatic additives. Furthermore, the antistatic coating for a flexible poly(vinyl chloride) (PVC) substrate was prepared by a dip-coating method using self-made waterborne polyurethane (WPU) as a binder. The results demonstrated that the aggregates of MWCNTs were successfully debundled into individually dispersed nanotubes by taking advantage of the high π–π interaction between MWCNTs and PTU. Compared with the chemical modification, the physically stabilized MWCNTs displayed fewer defects (ID/IG ∼ 0.853). Compared with the pure WPU coating, the sheet resistivity of the MWCNTs/CB/PTU/WPU coating decreased sharply from 1016 to 108 Ω at 0.5 wt % loading of MWCNTs, which met the requirement of antistatic applications. With further increase of the MWCNT content, the MWCNTs/CB/PTU/WPU coatings exhibited continually decreasing sheet resistivity and reached remarkably low surface resistance of 104 Ω at 2.0 wt % loading of MWCNTs, which was realized by the formation of conducting networks of synergistic MWCNTs and CB-induced low percolation threshold. The facile one-pot preparation of biobased PTU and simple production of MWCNT dispersion promise an ideal additive for antistatic and conductive-related applications, especially for flexible substrates.