In confronting the global climate change, reusing waste asphalt materials stands out as a key strategy for the transportation sector to preserve natural resources and reduce the carbon footprint. Recycling additives or rejuvenators are usually required in this practice, especially for boosting the recycling rate. Given the imperative need for a general compositional design principle of rejuvenators, we previously proposed an innovative formulation concept by combining softeners with asphaltene dispersants, and reported that the use of dispersants largely reduced the total quantity of rejuvenators needed and thus would minimize the environmental impacts. The present study is aimed for probing the molecular mechanisms underlying this observation, with additional interest focused on the synergistic effect of the dispersants with resins and also on the impacts due to their self-association. Selection of representative materials consisted of three types of dispersants including an ionic liquid, a phenolic amphiphile, and an ester plasticizer, in combination with an aromatic oil as the softener. Long-time molecular dynamics (MD) simulation was employed to inspect the aggregation of asphaltenes. Quantum chemical (QC) computation was performed to provide insights into the source of different dispersing behaviors. The results indicated that the three dispersants all acted in concert with resins in dispersing asphaltenes. The dispersion characteristics of asphaltenes could be viewed as a net result of the two competing mechanisms of the dispersing capability and self-association of the dispersant used. The ionic liquid exhibited much higher propensity to self-association at increasing concentrations than the phenolic dispersant, and yet the optimum performance was achieved for both when they were added at low dosages. The ester plasticizer showed minimal self-association and yielded improved dispersion with increasing concentrations. In all cases, the dispersing functionality mainly originated from the presence or formation of significant electron-withdrawing sites, collectively due to the highly electronegative cation and anion, hydrogen bonding, and polar groups. Comparison of the dispersing power was also conducted from different perspectives. The findings are expected to provide molecular insights for formulating versatile and more environmentally benign asphalt rejuvenators.

中文翻译：

---

掺有沥青质分散剂的软化剂与树脂协同作用：沥青再生的分子机制

在应对全球气候变化的过程中，废弃沥青材料的再利用成为交通运输行业保护自然资源和减少碳足迹的一项关键战略。在这种实践中通常需要回收添加剂或再生剂，特别是为了提高回收率。鉴于迫切需要再生剂的一般组成设计原则，我们之前提出了将软化剂与沥青质分散剂相结合的创新配方概念，并报告说，分散剂的使用大大减少了所需再生剂的总量，从而最大限度地减少了对环境的影响。本研究旨在探讨这一观察结果背后的分子机制，另外的兴趣集中在分散剂与树脂的协同效应以及由于它们的自缔合而产生的影响。代表性材料的选择包括三种类型的分散剂，包括离子液体、酚类两亲物和酯类增塑剂，并结合芳香油作为软化剂。采用长时间分子动力学（MD）模拟来检查沥青质的聚集。进行量子化学（QC）计算是为了深入了解不同分散行为的来源。结果表明，三种分散剂均与树脂协同作用，分散沥青质。沥青质的分散特性可以被视为分散能力和所用分散剂自缔合这两种竞争机制的最终结果。随着浓度的增加，离子液体比酚类分散剂表现出更高的自缔合倾向，但当它们以低剂量添加时​​，两者都达到了最佳性能。酯类增塑剂表现出最小的自缔合，并且随着浓度的增加而产生改善的分散性。在所有情况下，分散功能主要源自显着吸电子位点的存在或形成，这些吸电子位点共同归因于高负电性阳离子和阴离子、氢键和极性基团。还从不同角度对分散能力进行了比较。这些发现有望为配制多功能且更环保的沥青再生剂提供分子见解。