| Electrostatic breakdown appears due to the discharge of electrostatic accumulation, this phenomenon significantly affects the safety of industry and people’s life. So developing electrostatic dissipation(electrostatic conduction) coatings to effectively prevent the accumulation of electrostatic and electrostatic breakdown has become a topic with great significance and value. Note that in practical applications, scratching is inevitable for coatings because of the external force or internal stress. In order to ensure the safe use of equipment or instruments, preparing electrostatic dissipation coatings that have reversible self-healing property arouses great interest of researchers worldwide. So far, developing reversible self-healing coatings with electrostatic dissipation capacity is still an interesting but difficult challenge today. This paper aimed at solving this problem.Starting with the design and synthesis of new multi-furan monomer and liquid hyperbranched polysiloxane, and employing acidified multi-walled carbon nanotubes(aCNTs) and grapheme(rGO) as conductors, respectively, new kind of thermally reversible self-healing polyurethane(PU) films with great static dissipation capacity were designed and synthesized on the base of Diels-Alder(DA) reaction. Our research work reported in this thesis mainly includes following three aspects.Firstly, a novel furan linear polyurethane(FPU) which contains a large amount of furan rings and hyperbranched polysiloxane terminated by multi-maleimide(HSiNCM) were designed and synthesized. Then, the polyurethane films(PU-DA-CNT) were prepared by the reactions among FPU, HSiNCM and aCNTs. The molecular structures of them were characterized many techniques.Secondly, the electrostatic dissipation, heat resistance and self-healing properties of PU-DA-CNT films were intensively studied. By analyzing surface resistance, electrostatic decay half-life and the conductivity, PU-DA-CNT2 containing 1.96wt% aCNTs has excellent electrostatic dissipation property. The surface resistance, electrostatic attenuation half-life and conductivity of PU-DA-CNT2 are 3.094×108 Ω, 0.07 s and 4.116×10-8 S·cm-1, respectively. When the loading of aCNTs is larger than 0.99wt%, the resultant PU-DA-CNT films have improved thermal stability according to TG results. The initial thermal decomposition temperature(Tdi) of PU-DA-CNT2 is as high as 283 oC, about 20-40 oC higher than those of conventional PU films. PU-DA-CNT2 film has excellent self-healing capability, which is mainly due to the principle of reversible reaction of DA bond. The cracks were repaired when after treated with a procedure of 130oC/5 min+150 oC/48 h, and this repairing can be repeatedly based on NMR spectra results. In addition, PU-DA-CNT2 film has excellent self-healing efficiency, its self-healing efficiency of the 1st cycle is as high as 92.54%, almost the highest value reported so far. Besides, the 2nd cycle self-healing efficiency is also higher than the most reversible self-healing materials. As a result, PU-DA-CNT films have excellent overall performances, including outstanding heat resistance, self-healing properties and electrostatic dissipation performance, which are the only thermal reversible self-healing material with both high temperature and high static dissipation capacity so far, showing great potential applications.Thirdly, rGO was used as the conductor to prepare another kind of PU films. The PU-DA-rGO films were found to have excellent electrostatic dissipation property and self-healing property. The main highlight of PU-DA-rGO films is that a low content of rGO can endow films with outstanding electrostatic dissipation performance. |
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