Effect of polydopamine-modified multi-walled carbon nanotubes on the thermal stability and conductivity of UV-curable polyurethane/polysiloxane pressure-sensitive adhesives

Abstract The conductivity and thermal stability of traditional polymers are generally not ideal, consequently endowing polymer-based pressure-sensitive adhesives (PSAs) with certain conductivity and heat resistance has become a popular design idea. Although multi-walled carbon nanotubes (CNTs) possess good electrical conductivity and thermal stability, their adhesion to the substrate is poor. Inspired by mussel chemistry, polydopamine (PDA) is adopted to modify CNTs to improve their adhesion to substrates. Eventually, polydopamine-modified multi-walled carbon nanotubes (PDA-CNTs) are added into the polyurethane/polysiloxane matrix, and a series of self-adhesive and heat-resistant conductive adhesives are successfully prepared under UV irradiation. As a result, the conductivity and thermal stability of PSAs are refined as expected. Especially when the content of PDA-CNTs is 4wt%, the conductivity reaches 1.2 × 10-5 S/cm. Comparing to pure polymer (PUA), the conductivity of PUATS4 is increased by six orders of magnitude. In addition, its heat resistance is also improved, and the carbon residue rate is up to 14.5wt% at 750°C. These excellent performances of PSAs will be beneficial to the applications in conductivity and thermal stability in the future.