Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria.
Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria.
Adv Colloid Interface Sci. 2018 Jun;256:1-22. doi: 10.1016/j.cis.2018.05.006. Epub 2018 May 18.
Despite the considerable advances of molecular-thermodynamic theory of micelle growth, agreement between theory and experiment has been achieved only in isolated cases. A general theory that can provide self-consistent quantitative description of the growth of wormlike micelles in mixed surfactant solutions, including the experimentally observed high peaks in viscosity and aggregation number, is still missing. As a step toward the creation of such theory, here we consider the simplest system - nonionic wormlike surfactant micelles from polyoxyethylene alkyl ethers, CE. Our goal is to construct a molecular-thermodynamic model that is in agreement with the available experimental data. For this goal, we systematized data for the micelle mean mass aggregation number, from which the micelle growth parameter was determined at various temperatures. None of the available models can give a quantitative description of these data. We constructed a new model, which is based on theoretical expressions for the interfacial-tension, headgroup-steric and chain-conformation components of micelle free energy, along with appropriate expressions for the parameters of the model, including their temperature and curvature dependencies. Special attention was paid to the surfactant chain-conformation free energy, for which a new more general formula was derived. As a result, relatively simple theoretical expressions are obtained. All parameters that enter these expressions are known, which facilitates the theoretical modeling of micelle growth for various nonionic surfactants in excellent agreement with the experiment. The constructed model can serve as a basis that can be further upgraded to obtain quantitative description of micelle growth in more complicated systems, including binary and ternary mixtures of nonionic, ionic and zwitterionic surfactants, which determines the viscosity and stability of various formulations in personal-care and house-hold detergency.
尽管胶束生长的分子热力学理论已经取得了相当大的进展，但理论与实验之间的一致性仅在个别情况下得以实现。一种能够为混合表面活性剂溶液中蠕虫状胶束生长提供自洽定量描述的通用理论，包括实验观察到的粘度和聚集数的高峰值，仍然缺失。作为创建这种理论的一个步骤，我们在这里考虑最简单的系统 - 来自聚氧乙烯烷基醚的非离子蠕虫状表面活性剂胶束，CE。我们的目标是构建一个与现有实验数据相符的分子热力学模型。为此，我们系统地整理了胶束平均质量聚集数的数据，从中确定了在不同温度下胶束生长参数。没有现有的模型可以对这些数据进行定量描述。我们构建了一个新模型，该模型基于界面张力、头基空间位阻和链构象分量的理论表达式，以及模型参数的适当表达式，包括它们的温度和曲率依赖性。特别关注表面活性剂链构象自由能，为此推导出了一个新的更通用的公式。结果，得到了相对简单的理论表达式。这些表达式中包含的所有参数都是已知的，这便于用实验很好地吻合各种非离子表面活性剂胶束生长的理论建模。所构建的模型可以作为进一步升级的基础，以获得更复杂体系中胶束生长的定量描述，包括非离子、离子和两性离子表面活性剂的二元和三元混合物，这决定了个人护理和家庭清洁配方中的各种制剂的粘度和稳定性。
