Razafindralambo Hary, Blecker Christophe, Mezdour Samir, Deroanne Claude, Crowet Jean-Marc, Brasseur Robert, Lins Laurence, Paquot Michel
Unite de Technologie des Industries Agro-Alimentaires, Centre de Biophysique Moleculaire Numerique, Faculte Universitaire des Sciences Agronomiques de Gembloux, 2 Passage des Deportes, B-5030 Gembloux, Belgium.
J Phys Chem B. 2009 Jul 2;113(26):8872-7. doi: 10.1021/jp903187f.
Interfacial properties of surfactants are dependent on the conformation adopted by the hydrophilic headgroup or/and the hydrophobic tail at the boundary limit of two immiscible phases. Here, we demonstrate the impacts of the carbonyl group (-CO-) location of the ester bond of sugar-based surfactants by comparing some properties of two closely related esters, octyl glucuronate and glucose octanoate, at the air-water interface. The carbonyl group location influences the rate and extent of interfacial adsorption and the rheology properties of sugar esters at the air-water interface, which were evaluated by dynamic surface tension and complex surface viscoelastic measurements. Octyl glucuronate adsorbs the fastest at the air-water interface whereas glucose octanoate reduces the dynamic surface tension at the lowest value and exhibits the highest film viscoelasticity. Differences are attributed to molecular conformation constraints inducing relevant changes to the surface coverage kinetic capacity and the interaction strengths of the octyl sugar ester adsorbed films at the air-water interface. All of the results are supported by the minimum cross-sectional area values per molecule determined by both experimental and computational approaches.
表面活性剂的界面性质取决于在两个不混溶相的边界处亲水头基或/和亲水尾所采取的构象。在此，我们通过比较两种密切相关的酯——辛基葡糖醛酸酯和葡萄糖辛酸酯——在气-水界面的一些性质，来证明糖基表面活性剂酯键中羰基（-CO-）位置的影响。羰基位置影响气-水界面处的界面吸附速率和程度以及糖酯的流变学性质，这些通过动态表面张力和复表面粘弹性测量进行评估。辛基葡糖醛酸酯在气-水界面吸附最快，而葡萄糖辛酸酯将动态表面张力降低到最低值并表现出最高的膜粘弹性。差异归因于分子构象限制导致气-水界面处辛基糖酯吸附膜的表面覆盖动力学能力和相互作用强度发生相关变化。所有结果都得到了通过实验和计算方法确定的每个分子的最小截面积值的支持。
