A Molecular Thermodynamic Model of Coacervation in Solutions of Polycations and Oppositely Charged Micelles
A Molecular Thermodynamic Model of Coacervation in Solutions of Polycations and Oppositely Charged Micelles
复制标题
聚阳离子和带相反电荷的胶束溶液中凝聚的分子热力学模型
DOI：
10.1021/acs.langmuir.3c00359
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发表时间：
2023
期刊：
影响因子：
3.9
通讯作者：
Larson, Ronald G.
中科院分区：
文献类型：
--
作者：
Ghasemi, Mohsen;Jamadagni, Sumanth N.;Johnson, Eric S.;Larson, Ronald G.
为了指导个人护理配方的合理设计，我们建立了一个分子热力学模型，预测了阳离子聚合物和含有中性和阴离子表面活性剂以及添加盐的混合胶束的凝聚。在使用过程中，由于调理洗发水的稀释而形成的这些凝聚物，将调理剂和其他活性物质沉积到头皮或皮肤上，并提供润滑作用。我们的模型考虑了混合熵、聚正离子与水的疏水相互作用、带相反电荷基团与胶束和聚阳离子结合的自由能，以及捕获聚正离子链和胶束上带电基团连接的静电相互作用。模型输出的是表面活性剂、聚阳离子、盐和水在凝聚体及其共存的稀相中的组成，以及结合分数和凝聚体体积分数。我们研究了总体组成（表面活性剂、聚阳离子和添加盐）、电荷分数对胶束和聚阳离子的影响，以及结合自由能对凝聚相图的影响。然后，我们对十二烷基硫酸钠(SDS) -JR30M、甲基椰子基牛磺酸钠(taurate) -JR30M和十二烷基丙氨酸钠(alaninate) -JR30M进行了共聚实验，其中JR30M是羟乙基纤维素（cat-HEC）的阳离子衍生物，并利用我们的模型对它们的共聚数据进行了合理化。为了与实验进行比较，我们还开发了一种参数化方案来获得所需的结合能和弗洛里-哈金斯χ参数。我们发现我们的模型预测与实验数据吻合得相当好，并且与含有JR30M的SDS相比，牛磺酸盐和丙氨酸盐的无硫酸盐表面活性剂显示出更大的2相区域。
To guide the rational design of personal care formulations, we formulate a molecular thermodynamic model that predicts coacervation from cationic polymers and mixed micelles containing neutral and anionic surfactants and added salt. These coacervates, which form as a result of dilution of conditioning shampoos during use, deposit conditioning agents and other actives to the scalp or skin and also provide lubrication benefits. Our model accounts for mixing entropy, hydrophobic interactions of polycation with water, free energies of bindings of oppositely charged groups to micelles and polycations, and electrostatic interactions that capture connectivity of charged groups on the polycation chain and the micelle. The model outputs are the compositions of surfactants, polycation, salt, and water in the coacervate and in its coexisting dilute phase, along with the binding fractions and coacervate volume fraction. We study the effects of overall composition (of surfactant, polycation, and added salt), charge fractions on micelles and polycations, and binding free energies on the phase diagram of coacervates. Then, we perform coacervation experiments for three systems: sodium dodecyl sulfate (SDS)–JR30M, sodium methyl cocoyl taurate (Taurate)–JR30M, and sodium lauryl alaninate (Alaninate)–JR30M, where JR30M is a cationic derivative of hydroxyethylcellulose (cat-HEC), and rationalize their coacervation data using our model. For comparison with experiment, we also develop a parametrization scheme to obtain the requisite binding energies and Flory–Huggins χ parameter. We find that our model predictions agree reasonably well with the experimental data, and that the sulfate-free surfactants of Taurate and Alaninate display much larger 2-phase regions compared to SDS with JR30M.