功能酸二次掺杂聚苯胺的防腐蚀性能

聚苯胺具有独特的掺杂脱掺杂特性，能在特定的反应条件下合成出形貌较好的纳米纤维，使得通过脱掺杂和二次掺杂能制备出拥有特殊防腐官能团的新型纳米材料。将硫酸体系中合成的聚苯胺纳米纤维经氨水脱掺杂，再用磷酸、对甲苯磺酸和酒石酸等功能酸在脱掺杂态聚苯胺基础上制备出二次掺杂态聚苯胺，测试了聚苯胺/环氧树脂复合涂层的防腐蚀性能，并与功能酸一次掺杂态聚苯胺进行了对比。结果表明，功能酸掺杂的聚苯胺都有一定的防腐蚀效果；功能酸二次掺杂态聚苯胺比一次掺杂态聚苯胺有更好的防腐蚀性能，二次掺杂态聚苯胺涂层拥有更高的阻抗，其中酒石酸二次掺杂态聚苯胺涂层的阻抗最高，浸泡120 d后为3.48×10⁷ Ω·cm²，较其一次掺杂态聚苯胺涂层高出一个数量级。

Anticorrosion property of polyaniline doped twice with functional acid

As polyaniline (PANI) has unique doping and dedoping characteristics, good morphology nanofibers can be synthesized under specific reaction conditions and new nanomaterials with special anticorrosion functional groups can be prepared via the dedoping and twice doping process. PANI nanofibers doped with sulfuric acid were dedoped by ammonia solution, and based on this dedoped PANI, twice doped PANI were prepared in phosphoric acid, p-toluene sulfonic acid and tartaric acid system respectively. The structure of doped and twice doped PANI was characterized by FT-IR spectrometer and UV-Vis absorption spectrometer. An electrochemical workstation was used to record the open circuit potential (OCP) and the electrochemical impedance spectroscopy (EIS) of polyaniline/epoxy composite coatings, and their anticorrosion mechanism were investigated theoretically. FT-IR spectra and UV-Vis spectra indicated that the state of PANI was doped PANI in its emeraldine salt form. The electrochemical testing results showed that every coating had certain anticorrosion performance and the impedance value suffered a significant decrease at the beginning of immersion because the coating was permeated by the corrosive medium. The impedance value of twice doped PANI and doped PANI tended to stabilize after immersion for 22 d and 60 d respectively, the protection effect could be explained by the assumption that metallic cations formed a passivating complex with the dopant anion released from PANI, which improved the barrier property of PANI coating and slowed down the further corrosion of the metal. PANI doped twice with functional acid had better anticorrosion performance than doped state and twice doped PANI had higher impedance. PANI doped twice with tartaric acid had the highest impedance, the impedance value was 3.48×10⁷ Ω·cm² after immersion for 120 d, an order of magnitude higher than its doped state.