目的 研究在海洋环境中假单胞菌对聚氨酯清漆涂层分解作用的影响。方法 将聚氨酯清漆涂层样品分别浸泡于无菌海水与含假单胞菌的海水中，对浸泡环境不同的样品利用电化学阻抗谱（EIS）评价涂层防腐性能，使用扫描电子显微镜（SEM）和傅里叶变换红外光谱（FTIR），观察对比涂层的表面形貌，并表征其分子结构变化。结果 1 h~35 d时，在无菌海水及假单胞菌海水中，样品Nyquist图的容抗弧直径以及Bode图的低频端阻抗模量均减小。与此同时，假单胞菌海水中浸泡样品的Nyquist图容抗弧直径与Bode图低频端阻抗模量的减小量明显大于无菌海水中的减小量。无菌海水浸泡的等效电路在1~48 h时为1个时间常数，5~35 d时增加为2个时间常数；假单胞菌海水浸泡的等效电路在1~48 h时只有1个时间常数，5~29 d时为2个时间常数，35 d时增加为3个时间常数。浸泡36 h时，无菌海水中浸泡样品的涂层电阻值为8.23× 107 Ω?cm2，而假单胞菌海水中样品的涂层电阻为5.14×107 Ω?cm2；至35 d时，无菌海水中样品的涂层电阻降为5.61×106 Ω?cm2，假单胞菌海水中样品的涂层电阻降至7.03×105 Ω?cm2。假单胞菌海水中样品的涂层电阻在36 h~35 d的减小量明显大于无菌海水中的减小量。由SEM结果可以观察到，浸泡30 d后，无菌海水中浸泡样品的表面光滑完整，而在含假单胞菌海水中的样品表面附着了大量细胞及其代谢产生的生物膜，并出现了大量微孔与粉化痕迹。通过FTIR结果可以发现，浸泡在假单胞菌海水中的样品的N—H和醚基中的C—O含量明显比无菌海水中浸泡的样品要低。结论 电化学结果表明，假单胞菌显著降低了涂层的腐蚀抗性，并导致了涂层的分解。SEM和FTIR的分析结果证明，假单胞菌通过破坏聚氨酯分子中的N—H和醚基中的C—O，造成了涂层的分解。

The work aims to investigate the influence of Pseudomonas sp. on the degradation of polyurethane varnish coating in marine environment. Polyurethane varnish coating samples were immersed in the sterile seawater and Pseudomonas sp. inoculated seawater respectively. Electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) were applied to evaluate the anti-corrosion property of coating, observe surface morphology and represent molecular construction of samples immersed in different environment. The capacitive loop diameters of Nyquist plots and low-frequency impedance of Bode plots for samples immersed in sterile seawater and Pseudomonas sp. in-oculated seawater decreased at 1 h~35 d, and the decrease of these data of Nyquist plot and Bode plot in Pseudomonas sp. inoc-ulated seawater was significantly larger than that in sterile seawater during the immersion. The equivalent electrical circuit (EEC) model for sterile seawater system had only one time constant at 1~48 h, and then two time constants at 5~35 d. In Pseudomonas sp. inoculated seawater, EEC model had only one time constant at 1~48 h, two time constants at 5~29 d, and then three time constants at 35 d. Coating resistance of samples was 8.23×107 Ω?cm2 in sterile seawater and 5.14×107 Ω?cm2 in Pseudomonas sp. inoculated seawater for 36 h. Coating resistance was 5.61×106 Ω?cm2 in sterile seawater and 7.03×105 in Pseudomonas sp. inoculated seawater for 35 d of immersion. Reduction of coating resistance of samples immersed in Pseudomonas sp. inoculated seawater was obviously larger than that in sterile seawater at 36 h~35 d. From SEM results, after 30 days of immersion, the surface of samples in sterile seawater was smooth and intact, but a layer of biofilm composed by cells and metabolite formed on samples surface immersed in Pseudomonas sp. inoculated seawater, and a plenty of pits and powdering traces were also found. From the results of FTIR, the content of C—O in the ether group and N—H of samples immersed in seawater inoculated with Pseudomonas sp. were significantly lower than that of samples immersed in sterile seawater. Through the electrochemical results, Pseudomonas sp. can significantly reduce the corrosion resistance of coating, and result in the degradation of coating. Results of SEM and FTIR prove that Pseudomonas sp. can damage the C—O in the ether group and N—H of polyurethane molecular, and then cause the degradation of coating.