Effect of Dispersed Tetradecanol Particles or Droplets on the Dynamic Surface Tension of Aqueous Tetradecanol Systems
Effect of Dispersed Tetradecanol Particles or Droplets on the Dynamic Surface Tension of Aqueous Tetradecanol Systems
复制标题
分散的十四醇颗粒或液滴对含水十四醇体系动态表面张力的影响
作者：
S. H. Myrick;E. Franses
对于处于溶解度极限的微溶表面活性剂，表面张力平衡通常很长，并且吸附会大大耗尽溶液。通过补充被吸附的材料并通过靠近表面，表面活性剂材料的分散颗粒或液滴可以将吸附到表面的速率增加几个数量级。由于颗粒迁移或扩散以及颗粒溶解的速率可以控制吸附速率，因此颗粒尺寸和制备方案可能非常重要。报告了十四醇在水中的行为，因为其在产生潜在肺表面活性剂应用的低动态表面张力方面的重要性，并且作为典型的微溶表面活性剂，在25 °C下的溶解度为0.3 ppm（1.4 μM）。在25、37和41 °C（后者高于十四醇熔点）下，在水或盐水（0.9重量% NaCl）中，用气泡法（从压力跃变和气泡半径测量）在恒定或脉动区域（1-80次循环/分钟）测量动态张力。通过使用表面状态方程的拟合数据从动态表面张力γ（t）推断动态表面密度Γ（t），其中γ = γ 0 - y，由压力-面积等温线确定，其通过朗缪尔槽和预防措施获得，以考虑可能的单层损失。在20-80 rpm和1500 ppm浓度下，观察到的张力远低于平衡值（22 ± 2 mN/m），低至9 mN/m。这些低张力被推断为与压缩的单分子层，而不是在空气/水界面较厚的膜。
For sparingly soluble surfactants at their solubility limit, the surface tension equilibration is usually very long, and adsorption depletes the solution considerably. By replenishing the adsorbed material and by being close to the surface, dispersed particles or droplets of the surfactant material can increase the rate of adsorption to the surface by orders of magnitude. Since the rates of particle migration or diffusion and particle dissolution can control the adsorption rates, the particle sizes and protocols of preparation can be quite important. The behavior of tetradecanol in water is reported for its importance in producing low dynamic surface tensions for potential lung surfactant applications and as a typical sparingly soluble surfactant, having a solubility of 0.3 ppm (1.4 μM) at 25 °C. The dynamic tension has been measured at 25, 37, and 41 °C (the latter is above the tetradecanol melting point) in water or saline (0.9 wt % NaCl), with a bubble method (measured from the pressure jump and the bubble radius) at constant or pulsating area (1-80 cycles/min). The dynamic surface densities Γ(t) were inferred from the dynamic surface tensions γ(t) by using the fitted data of the surface equation of state Γ(Π), where Π = γ 0 - y, determined from pressure-area isotherms, which were obtained with a Langmuir trough and precautions to account for possible monolayer losses. At 20-80 rpm and the concentration 1500 ppm, tensions much lower than the equilibrium values (22 ± 2 mN/m) and as low as 9 mN/m were observed. These low tensions were inferred to be related to compressed monolayers rather than thicker films at the air/water interface.