Heat-resistant polyurethane films with great electrostatic dissipation capacity and very high thermally reversible self-healing efficiency based on multi-furan and liquid multi-maleimide polymers

Abstract

Single-function, low temperature resistance and low self-healing efficiency are three big bottlenecks that restrict the applications of existing reversible self-healing polyurethane (PU) films in leading industries. Herein, starting with synthesizing new polymer with multi-furan rings (FPU) and liquid hyperbranched polysiloxane terminated by multi-maleimide (HSiNCM) as well as using acidified multi-walled carbon nanotubes (aCNTs) as the conductor, a new kind of thermally reversible self-healing PU film that simultaneously has good processing property, high thermal stability and great electrostatic dissipation capacity, coded as PU-DA-CNTs, was designed and synthesized. The thermally reversible ability of PU-DA-CNTs was based on the Diels–Alder (DA) reaction. With about 1.96–4.76 wt% aCNTs, the resultant PU-DA-CNT films have outstanding thermal stability; their initial decomposition temperatures are 283–298 °C, at least about 20–40 °C higher than those of reversible self-healing PU films in the literature; in addition, the cracks on the surface of the PU-DA-CNT film can be self-healed after the film was maintained at 130 °C for 5 min, and the self-healing efficiency of the 1^st cycle is as high as 92.54%, almost the highest value for reversible self-healing materials reported to date. Multi-maleimide groups in PU-DA-CNTs provide higher proceeding possibility of the DA reaction between furan rings and maleimide groups, thus leading to a high self-healing efficiency. On the other hand, PU-DA-CNT films have outstanding electrostatic dissipation capacity; their surface resistance, static decay half-life and conductivity are 3.094 × 10⁸ Ω, 0.07 s and 4.116 × 10⁻⁸ S cm⁻¹, respectively. These attractive integrated performances of PU-DA-CNT films are proved to be derived from the special structure and advantages of FPU, HSiNCM and aCNTs.