L-色氨酸改性氧化石墨烯复合水性环氧树脂涂层的制备及性能

Preparation and Properties of L-Tryptophan Modified Graphene Oxide Composite Waterborne Epoxy Coatings

采用L-色氨酸(L-Trp)为改性剂,对氧化石墨烯(GO)进行改性处理,随后将改性的氧化石墨烯分散于水性环氧树脂中,再经聚酰胺固化剂固化,制得L-色氨酸改性氧化石墨烯复合水性环氧树脂涂层。利用电化学交流阻抗、动电位极化曲线等测试手段分别对水性环氧树脂涂层、氧化石墨烯复合水性环氧树脂涂层以及L-色氨酸改性氧化石墨烯复合水性环氧树脂涂层(L-Trp/GO/epoxy)的耐腐蚀性能进行了研究。结果表明,L-Trp/GO/epoxy涂层在3.5%NaCl溶液中浸泡15 d后的交流阻抗值为2.16×10^7Ω·cm^2,比环氧树脂涂层提高了近103倍,耐腐蚀性能最强。另外,从L-色氨酸改性氧化石墨烯的透射电镜照片发现,经L-Trp改性的GO从多层被剥离为更薄的片材,并均匀分散于水溶液中。L-Trp/GO/epoxy涂层的扫描电镜照片显示,涂层表面平整光滑致密,GO片材与基体树脂粘连紧密,无明显团聚现象。

The composite waterborne epoxy coatings were fabricated by dispersing L-tryptophan modified graphene oxide sheets(L-Trp/GO) into waterborne epoxy coatings at high speed. The L-tryptophan modified graphene oxide composite waterborne epoxy coating(L-Trp/GO/epoxy) was prepared through curing with polyamide hardener. The corrosion resistance performances of the sample coatings were characterized by electrochemical impedance spectroscopy, potentiodynamic polarization curve and other testing methods. The results demonstrate that L-Trp/GO/epoxy coating has the highest corrosion resistance of 2.16×10^7 Ω·cm^2 after immersion in 3.5% NaCl solution for 15 d, nearly 3 orders of magnitude higher than that of the pure epoxy coating. Additionally, the TEM images of the L-Trp/GO/epoxy coating show that the stacked GO sheets are exfoliated to a thinner sheet structure after modified with L-Trp, contribute to dispersing GO sheets uniformly in the waterborne epoxy resin. Further, its SEM images suggest that the surface of the coating is smooth and dense, and the GO sheets adhere tightly with the matrix epoxy resin without obvious agglomeration.