Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan 250100, PR China.
Langmuir. 2011 Aug 2;27(15):9253-60. doi: 10.1021/la201676u. Epub 2011 Jul 6.
The aggregation behaviors of branched block polyether Tetronic 1107 (T1107) at an air/liquid surface was investigated in mixed solvents consisting of water and one of the following polar cosolvents: ethanol, n-propanol, ethylene glycol (EG), or glycerol (GLY). Surface tension measurements provide information about the effects of cosolvents on the critical micellization concentration (cmc), the standard Gibbs energy (ΔG°(mic)), the maximum surface excess concentration (Γ(max)), the minimum area per polyether molecule at the air/liquid surface (A(min)), and the standard free energy of adsorption (ΔG°(ads)). The addition of ethanol and n-propanol to water disfavors the micellization and progressively increases the cmc of T1107, whereas the cmc decreases with the addition of EG and GLY. The values of ΔG°(mic) of T1107 are all negative in mixed solvents, and their absolute values become smaller as the ethanol or n-propanol content increases but become larger as the EG or GLY content increases. The cosolvents have a significant effect on the surface adsorption and cmc, and the order is as follows: n-propanol-water > ethanol-water > water > EG-water > GLY-water. The octanol/water partition coefficient (log P) of the cosolvent is used to correlate the effects, and it could capture the effect of cosolvents on the cmc qualitatively. The surface dilational rheological properties of T1107 in water and water-alcohol mixtures were also studied by surface dilational viscoelasticity and surface tension relaxation measurements. The dilational elasticity decreases monotonously in the presence of ethanol or n-propanol. With the increasing concentration of EG and GLY, the dilational elasticity of T1107 passes through a maximum that coincides with the change in Γ(max).
支化嵌段聚醚 Tetronic 1107（T1107）在由水和以下一种极性共溶剂组成的混合溶剂中的聚集行为进行了研究：乙醇、正丙醇、乙二醇（EG）或甘油（GLY）。表面张力测量提供了关于共溶剂对临界胶束浓度（cmc）、标准吉布斯自由能（ΔG°(mic)）、最大表面过剩浓度（Γ(max)）、空气/液体表面每个聚醚分子的最小面积（A(min)）和标准吸附自由能（ΔG°(ads)）的影响的信息。乙醇和正丙醇的加入不利于胶束化，并逐渐增加 T1107 的 cmc，而 EG 和 GLY 的加入则降低了 cmc。T1107 在混合溶剂中的ΔG°(mic)值均为负值，其绝对值随乙醇或正丙醇含量的增加而减小，但随 EG 或 GLY 含量的增加而增大。共溶剂对表面吸附和 cmc 有显著影响，其顺序如下：正丙醇-水>乙醇-水>水>EG-水>GLY-水。用溶剂的辛醇/水分配系数（log P）来关联这些影响，可以定性地捕捉到共溶剂对 cmc 的影响。还通过表面膨胀粘弹性和表面张力弛豫测量研究了 T1107 在水和水-醇混合物中的表面扩张流变性质。在存在乙醇或正丙醇的情况下，膨胀弹性单调下降。随着 EG 和 GLY 浓度的增加，T1107 的膨胀弹性通过与Γ(max)变化一致的最大值。
