【正文】 。此 外，可以得出結論，抑制 機理 是一個物理 過程。只形成了一個 S 型證明在金屬表面形成了單層的緩蝕劑分子膜。在較高濃度時η的降低表明，沒有形成連續(xù)的膜是由于在較高濃度時形成了膠束 [19]。這表明低濃度時在金屬 /溶液界面形成了簡單的緩蝕劑膜。 該吸附過程 的不同決定參數 幾乎全部取決于 這些抑制劑的化學結構。 在降低緩蝕劑濃度時緩蝕效果增加的實現(xiàn)是因為分子機理而非形成膠束。 150ppm被認為是一個關鍵劑量，是由于金屬表面完全被緩蝕劑分子覆蓋，這里出現(xiàn)了最大緩蝕效率。緩蝕劑可以合理解釋為膠束和這些緩蝕劑（兩親分子）膠束的形成。 以 200和 100ppm降低劑量， 緩蝕效率增加更 大 的程度，直到達到約 100 ppm的最高值。 . Effect of inhibitor doses Fig. 6 represents the dose effect of the synthesized corrosion inhibitor on their corrosion inhibition efficiency for aluminum alloy in acidic medium at 25 ?C. It is clear that at higher inhibitor dose (400 ppm), η appears in the lowest values. Decreasing the doses to 200 and 100ppm increases the inhibition efficiencies to higher extent, till reaches its maximum value around 100 ppm. Meanwhile, further decrease in the inhibitor concentrations (50, 25 and 10 ppm) turns the efficiencies to lower values, but remains higher than those belonged to 400 ppm. That behavior could be rationalized to the micellization and micelle formation of these inhibitors (amphiphiles). At lower inhibitor doses (10, 25 and 50 ppm), the molecules are pumped to the interfaces due to their amphipathic character and participated in the formation of isolating layer at the metal surface, hence the corrosion efficiency increased. The dose of 150ppm is considered a critical dose, that is due to the metal surface is pletely covered by inhibitor molecules, which appears the highest corrosion inhibition efficiency. That is due to micelle formation near that concentration. The lowering in corrosion inhibition efficiencies upon increasing the inhibitor concentrations implements the idea that the inhibition occurred through a molecular mechanism and not the micellar one. Fig. 6 表示已合成的緩蝕劑對鋁合金在 25?C 時酸性介質中緩釋效果的劑量影響。 那引導這些分子在金屬 /溶液界面累積。這也說明了它們作為緩蝕劑的低效率。這可以從吸附自由能的值(Table 2)看出 。 已合成的席夫堿中較高含量的聚環(huán)氧乙烷含量增加了它的親水性。 . Effect of polyethylene oxide chain length Fig. 5 represents the variation of corrosion inhibition efficiencies of nonionic Schiff base amphiphiles bearing different ethylene oxide contents (molecular weights = 400, 1000, 2020 and 3000) at constant hydrophobic chain (for palmitate derivative). The corrosion inhibition efficiency was increased by decreasing the PEO content. Higher PEO content increases the hydrophilicity of the synthesized inhibitors. Hence, inhibitor molecules tend to migrate to the bulk of the aqueous medium , which decreases their adsorption tendency at the interfaces. That can be observed from their values of adsorption free energies, (Table 2). Consequently, their accumulation at the metal surface decreased. That explains their low efficiency as corrosion inhibitors. On contrarily, derivatives which have lower PEO content had higher surface activity due to their higher hydrophobicity. That directs these molecules towards the accumulation at the metal/solution interfaces. Hence, their corrosion inhibition efficiencies increased [18]. . 聚環(huán)氧乙烷鏈 長度 的影響 Fig. 5表示不同含量（分子量 =400, 1000, 2020 和 3000）環(huán)氧乙 烷的非離子型席夫堿兩親分子以疏水鏈為常量（ 棕櫚酸酯衍生物 ）的緩蝕效率的變化。 Figs. 3和 4表明， 兩種技術得到的緩蝕效率有很接近的值而有高度的可比性。 這使得分子直觀的在侵蝕介 質中作為一層平整的膜，消除了它的破壞性行為，如 SB2020oleate 所示 (Amin =)。 增加吸附趨勢（在吸附自由能條件下， Δ Gads, Table 2)使緩蝕劑分子移向金屬 /腐蝕介質的界面，在這里緩蝕劑分子是一個屏障，因此腐蝕過程 穩(wěn)步下降 [25]。 這些鏈的盤曲（以飽和鏈為例）或 /和不飽和點（以油酸衍生物為例）的存在增加了上述的重疊。 由烷基鏈形成一個緊密的非極性層。第一，這些緩蝕劑在相界面的表面活性。比較不同 疏水鏈 的緩蝕速率 (Fig. 3)得出如下趨勢： 油酸 硬脂酸 棕櫚 癸酸 。顯然，緩蝕效率隨著疏水鏈上亞甲基的重復數目的增加而增大。 . Corrosion inhibition efficiency . Effect of alkyl chain length Fig. 3 represents the variation of corrosion inhibition efficiency of the synthesized nonionic Schiff bases amphiphiles containing constant ethylene oxide content (n = 45 EO units). It is clear that the inhibition efficiency increased by increasing the number of repeated methylene groups in the hydrophobic chains. Schiff base polyethylene glycol ABA2020 showed the maximum corrosion inhibition efficiency at %. Comparison between the corrosion rate of the different hydrophobic chains (Fig. 3) showed the following trend: oleate stearate palmitate decanoate. That behavior could be referred for two factors. First, the surface activity of these inhibitors at the interfaces. Second, the longer hydrophobic chains neighbored to each other can easily overlapped. That forms a condensed nonpolar layer consists of the alkyl chains. This layer faced the polar aggressive medium, hence good isolation occurred and the corrosion process stopped. The presence of coiling in these chains (in case of saturated chains) and/or unsaturation sites (in case of oleic acid derivative) enhances the mentioned overlapping. That effect appears obviously in the case of stearate and oleate derivatives (SB202018 and SB2020oleate). Increasing the adsorption tendency (in terms of adsorption free energy, Δ Gads, Table 2) directing the inhibitor molecules towards the metal/corrosive medium interface where the inhibitor molecules act as a barrier。 吸附趨勢是指水相和疏水鏈之間的作用，它迫使兩