【文章內(nèi)容簡(jiǎn)介】 (polar phase), which forced the molecules to adsorb at the air– water interface and to micellize in the bulk of their solutions in order to decrease that repulsion. While, the lowest critical micelle concentration was found at base containing PEO2020 and the hydrophobic chains is oleate (Table 2), which referred to the above reasons and also to the unsaturation sites in the oleate chain which increases the repulsion extent. The effectiveness (π cmc) values showed gradual decrease by increasing the hydrophobic chain length indicating the increasing of accumulated surfactant molecules at the interface. The maximum accumulation was indicated by the lowest surface tension depression at the critical micelle concentration and was recorded for SB2020oleate molecules at 44 mN/m . The effectiveness values as well as the maximum surface excess considered as a clear description for the accumulation extent of amphiphiles molecules at the air– water interface. The calculated values of the maximum surface excess showed increasing trend from SB2020decanoate to SB2020oleate as represented from the slope of preCMC region of surface tension profile (Fig. 1). The maximum surface excess values were increased from decanoate to oleate derivatives indicating higher surface concentration and increasing number of surfactant molecules at the interface. Values of the minimum surface area occupied by the nonionic Schiff base amphiphiles at the interface (Amin) were calculated according to the equation: where, Γ max and NAV are the maximum surface excess and Avogadro’ s number, respectively. Increasing the maximum surface excess values indicates the increasing of adsorbed molecules at the interface, hence the area available for eachmolecule will decrease. That causes the pacting of surfactant molecules at the interface to form denser layer. The values of critical micelle concentration, effectiveness, maximum surface excess and minimum surface area of the Schiff base nonionic amphiphiles were listed in Table 2. . 表面活性 . 疏水鏈 （非極性鏈） 長(zhǎng)度的影響 Fig. 1表示表面張力與合成的包含相同分子量聚乙二醇 (n=45 EO 單元 )的非離子型兩親席夫堿濃度直接的聯(lián)系。很明顯，表面張力具有非離子型表面活性劑的特征 ，出現(xiàn)了 相對(duì)較高的表面張力值。 隨著從 10到 18增加疏水鏈上的亞甲基數(shù)， 臨界膠束濃度逐漸 降低 [17]。 這種影響 在 前人 的 著作中已經(jīng) 有 了 解釋 [20,21]，是 由于疏水鏈（非極性相）和水相（極性相） 存在 斥力 ，這種斥力迫使在空氣 /水界面形成分子吸附和在大部分溶液中形成膠束以減小它。含 有 PEO2020和油酸做疏水鏈的席夫堿 (Table 2) 最低臨界膠束濃度 為 ， 其中提到的上述原因，也是為了在油酸鏈 增加 不飽和點(diǎn)的排斥程度。 緩蝕率的值 (π cmc) 隨著增加疏水基的鏈長(zhǎng)逐漸降低，它說(shuō)明表面活性劑分子在界面的累積量增加 。最大累積值是 臨界膠束濃度 下的最低表面張力，最大值為 SB2020oleate 的 分子數(shù)在 44 mN/m時(shí)的值 。效率值 也是最大 剩余 表面，是兩親分子在空氣 /水界面上的聚集程度的 一個(gè)明確的說(shuō)明 。最大 剩余面積值的計(jì)算表明，從 SB2020decanoate 到 SB2020oleate 增加趨勢(shì)，表示表面張力前臨界膠束濃度區(qū)域的斜率范圍。 從癸酸到油酸衍生物增加最大 剩余 表面，顯示有較高的表面濃度，表面活性劑在相界面的分子數(shù)也隨著增加。 非離子 型 希夫 堿 兩親分子在界面 所占最小表面積值（ Amin） 計(jì)算 公式 如下： 式中Γ max表示最大 剩余 面積， NAV 表示阿伏伽德羅數(shù) 。最大剩余面積的增加是表示界面分子吸附的增加，因此每個(gè)分子的可用區(qū)域減少。表面活性劑分子間的壓迫 力使得在相界面形成致密的膜層。 臨界膠束濃度， 緩蝕效率 ，最大 剩 余表面 和 最低的 非離子型兩親席夫 堿 最小表面區(qū)域的值 分別 列于表 2。 . Effect of polyethylene oxide content (polar chains) Fig. 2 represents the effect of ethylene oxide contents on the surface activities of the synthesized nonionic Schiff base amphiphiles at constant hydrophobic chain length (16 methylene groups). It is clear that increasing the number of ethylene oxide units within the nonionic moiety from 9 to 45 and 68 EO units increases the hydrophilic characters of these molecules, which increases their critical micelle concentrations and also their surface tension values. Increasing of the CMC values can be referred to the formation of hydrogen bonds (HBs) between amphiphiles and water molecules. HBs increase the adsorption of these amphiphiles at the air– water interface, which increases the CMC values gradually. The maximum CMC value was observed for the longest polyethylene oxide chain (n = 68) at mM/L. On the other hand, the effectiveness (π CMC) values of the synthesized Schiff base nonionic amphiphiles SBn 16 were increased gradually by decreasing the length (n) of the nonionic moiety (where n = 9, 45 and 68) [22,23]. The effectiveness (π CMC) and the efficiency (pC20) values showed an increasing trend by increasing the hydrophobic chain length. The maximum lowering in the surface tension values was corresponded to the SB400palmitate. The maximum surface excess (Γ max) values showed lower surface concentration for the Schiff base amphiphiles which have the higher ethylene oxide content. The highest value of the maximum surface excess was observed for SB40016 (Table 2). On contrarily, the minimum surface area (A min) values increased by increasing the nonionic chain lengths, the maximum value of the surface area was observed for SB300016 (Table 2). . 聚環(huán)氧乙烷含量的影響（極性鏈） Fig. 2 表示已合成的非離子型席夫堿的疏水鏈長(zhǎng)為常 數(shù)（ 16 亞甲基組）時(shí)，環(huán)氧乙烷對(duì)表面活性的影響 。 很明顯，在 非離子基團(tuán) 中從 9到 45和 68增加環(huán)氧乙烷的單元數(shù) 這些分子的親水 性也增強(qiáng)，它增加了它們的 臨界膠束濃度 和表明張力值。 臨界膠束濃度值的增大指明在兩親分子和水分子之間形成了氫鍵 (HBs).氫鍵增加了這些兩親分子在空氣 /水界面吸附，這也逐漸增加了臨界膠束濃度值。最大臨界膠束濃度值 的得出是在 聚環(huán)氧乙烷鏈最長(zhǎng) （ n=68）時(shí)濃度為 mM/L下。 另一方面，非離子型席夫堿兩親分子 SBn 16的緩蝕效果 (π CMC)