1、 关键词：非离子表面活性剂 希夫碱 吸附 表面张力 缓蚀 缓蚀速率 缓蚀效率 a b s t r a c t A novel series of self-assembled nonionic Schiff base amphiphiles was synthesized and their chemical structures were confirmed using elemental analysis, FTIR spectroscopy and 1H NMR spectra. The surface activities of these amphiphiles were deter
2、mined based on the data of surface and interfacial tension, critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area. Thermodynamics of adsorption and micellization processes of these amphiphiles in their solutions were also calculated. The surface a
3、nd thermodynamic data showed their higher tendency towards adsorption at the interfaces. The synthesized amphiphiles were evaluated as corrosion inhibitors for aluminum (3SR) at different doses (400 10 ppm) in acidic medium (4N HCl) using weight loss and hydrogen evolution techniques. The corrosion
4、measurements showed that the synthesized nonionic Schiff bases could serve as effective corrosion inhibitors. The surface and corrosion inhibition activities were correlated to the chemical structures of the inhibitors. 摘要 一种新型系列自组装非离子型两亲 Schiff 碱被合成，它们的化学结构用元素分析法确定，红外光谱和核磁共振氢谱。这些两亲分子的表面活性的确定要基于表面张力
5、和界面张力、临界胶束浓度，效果，效率，最大和最小表面积的数据。他们的方案也计算了吸附热力学和这些两亲分子胶束化过程。表面 状况数据 和热力学数据显示它们对在界面吸附有较大的倾向 。 用 失重 法 和析氢技术 评价 不同剂量（ 400-10ppm）的 合成的两亲分子 作为铝（ 3SR）的缓蚀剂在酸性介质（ 4N HCl）中的缓蚀效果。 腐蚀实验表明合成的非离子型席夫碱是有效的缓蚀剂 。表面活性和缓蚀性能 与 缓蚀剂的化学结构有关。 1. Introduction Ferrous, nonferrous metals and their alloys are extensively used in
6、 industry. To remove unwanted scale and salt deposits or mill scales formed during manufacture, metals are immersed in acid solutions, which are known as an acid pickling bath. After the scale is removed, the metal may be subjected to attack by the acids. In order to reduce the degree of metal attac
7、k and rate of consumption of the acid, corrosion inhibitors are added to the pickling solutions Hydrochloric and sulphuric acids are the most commonly used acids in the pickling bath 1,2. Most commercial inhibitor formulations include aldehydes and amines in their structure 3,4. The choice of the in
8、hibitors is based on two considerations: first, they could be synthesized conventionally from relatively cheap raw materials； second, they contain the electron clouds on the aromatic rings or, the electronegative atoms such as benzene ring-containing Schiff bases 5,6. Schiff base inhibitors have bee
9、n reported as effectively corrosion inhibitors for steel, copper and aluminum 7 9. These substances generally become effective by adsorption on the metal surface. Adsorption depends on the nature and charge of the metal and also, on the chemical structures of the inhibitors 10. Self-assembled mono-
10、layer can provide a convenient method for corrosion inhibition,since the process of self-assembling is simple, and the chemical composition and thickness of self-assembled mono layers can be tailored by design and synthesis of the adsorption agent. The practical applications of self-assembled mono l
11、ayers as corrosion inhibitors were explored by several investigators 11 14. It was found that densely packed self-assembled mono layers heteroatom containing compounds were effective for blocking certain electrochemical processes, thus effectively act as corrosion inhibitors. In this study, differen
12、t self-assembled inhibitors containing polyethylene glycol chains with different molecular weights and Schiff base terminal group were synthesized. The corrosion inhibition efficiencies of these compounds towards aluminum alloy were examined using weight loss and hydrogen evolution techniques. The s
13、urface activities of these Schiff base amphiphiles and the surface activity corrosion inhibitionchemical structure relationships were also discussed. 1. 概括 黑色 金属 ，有色金属及其合金被广泛应用于工业 中。 要除去金属在生产过程中形成的未知污垢和盐垢或 铣 垢，金属要浸泡在酸液中，也就是我们常说的 酸洗浴 。除去垢之后，金属可能会受到酸的腐蚀。为了降低金属受腐蚀的程度和酸液的消耗速率，我们需要在酸洗液中添加缓蚀剂。 盐酸和硫酸是酸洗浴中最
14、常用的酸 1,2.很多商业缓蚀剂组成中都含有醛和胺 3,4。选择缓蚀剂要考虑的两个因素是：一 ，它 们能够很方便的由相关原料合成；二， 它们含有带电子的苯环或者是有电负性原子，如含有芳香环的席夫碱 5,6。据报道，席夫碱类缓蚀剂对铁、铜铝都有效缓蚀效果 7 9。 这些物质通常 能 有效地吸附在金属表面。 吸附取决于金属的性质和缓蚀剂的化学结构 10。自组装单层膜是缓蚀的一种便捷方法，膜的 化学组成和自组装单分子膜的厚度可 通过 设计吸附剂的合成 实现。一些研究机构已经开发了应用于实际的自组装膜缓蚀剂 11 14。 实验结果发现， 结果发现， 含有杂原子化合物 的致密 自组装单层 能 有效阻止某
15、些电化学过程，从而 能够作为有效的缓蚀 剂 。 在本项目的研究中， 不同的自组装 缓蚀剂由 含有不同分子量聚乙二醇 链端基 合成 的席夫碱制备 。 表征 这些化合物对铝合金缓蚀效率分别采用失重 法 和析氢的技术。 本文探讨了这些席夫碱的表面活性，以及表面活性、腐蚀抑制、化学结构之间的联系。 2. Experimental procedures 2.1. Synthesis of Schiff bases 0.5 mol of anisaldehyde was condensed with 0.5 mol of p-aminobenzoic acid in the presence of 250
16、 mL of ethyl alcohol as a solvent. The reaction mixture was refluxed for 6 h and then left overnight until the product was precipitated. The product was washed by petroleum ether and recrystallized from ethanol. The final product was dried under vacuum at 40 C 15. The produced Schiff base was denote
17、d as SB and the chemical structure was represented in Scheme 1. Scheme 1. Chemical structure of the synthesized Schiff base. Scheme 2. Chemical structure of the synthesized nonionic Schiff base. 2.实验步骤 2.1.合成席夫碱 0.5mol 的 茴香醛 和 0.5mol 的对氨基苯甲酸以 250mL 的无水乙醇做溶剂。反应混合物回流 6小时，放置过夜直到产物沉淀出来。用石油醚洗涤，再用乙醇重结晶。最终
18、产物在 40C 真 空干燥。合成的席夫碱记为 SB，化学结构式 如 方案 1 表示。 方案 1.合成席夫碱的化学结构 方案 2. 合成非离子型的席夫碱的化学结构式 2.2. Synthesis of nonionic Schiff bases amphiphiles Polyethylene glycol monoalkanoate of different molecular weights (400, 1000, 2000 and/or 3000, where, n = 9, 45 and/or 68) and different alkyl chain lengths (R = 10:
19、decanoate； 16: hexadecanoate 8: octadecanoate and/or oleate) were esterified by the synthesized Schiff base SB in equimolar ratio in xylene as a solvent and p-toluene sulfonic acid (0.01wt.%) as a dehydrating agent 16. The reaction was continued until complete removal of the water of the reaction. V
20、acuum distillation was performed to remove the unreacted materials and the solvent, Scheme 2. The produced nonionic Schiff bases were denoted as SB-PEG-alkanoate (R) and listed in Table 1. 2.2. 非离子型两性席夫碱的合成 等摩尔比的不同分子量的聚乙二醇（ 400,1000,2000 和 /或 3000 ， n=9.45 和 /或 68）和不同链长的单链烷烃（ R=10：癸酸； 16；棕榈酸； 18：硬脂酸
21、和 /或油酸）缩合的聚乙二醇酯与已合成的席夫碱在以二甲苯为溶剂，对甲苯磺酸（ 0.01wt.%）做 干燥剂 16 的条件下进行酯化反应。反应持续到体系水分完全除去。真空蒸馏除去未反应的物料和溶剂，方案 2 .记非离子型席夫碱产物为 SB-PEG-链烷酸（ R），列在表 1 中。 2.3. Structural analysis The elemental analyses were performed for the synthesized surfactants using Vario Elementar instrument for elemental analysis, Fourier-
22、transform infrared spectrophotometer for FTIR spectra and Bruker model DRX-300 NMR spectrometer with TMS as an internal standard for 1H NMR spectra. The results were represented in Table 1. 2.3. 结构分析 用 Vario 元素分析仪对合成的表面活性剂做元素分析，用 傅里叶变换红外光谱仪 做 红外光谱及用 布鲁克模型的 DRX - 300 核磁共振 以 TMS 内部 标准 核磁共振光谱 。结果列在表 1
23、中。 2.4. Surface and interfacial tension measurements Surface tension measurements were made for freshly prepared inhibitors solutions in a concentration range of 0.1 0.0001M/L at 25 C using a Du-Nuoy Tensiometer-Kruss-K100. Also, interfacial tension measurements were made for inhibitors oil systems 17. 2.4.表面张力和界面张力 测定
