Abstract Clustering behaviour of hexa-tert-butylhexa-peri-hexabenzocoronene (HTBHBC) and its derivatives has been used as a model system to mimic that of natural asphaltenes. We used light scattering and 1H-NMR spectroscopy, complemented by molecular dynamics simulation, to examine HTBHBC and its derivatives in toluene and toluene/heptane mixture, over a range of concentrations. The dispersibility of HTBHBC in toluene was found to be strongly dependent on its concentration. At concentrations below 5 mg/mL, HTBHBC appears to be fully dispersed and clustering equilibrium was reached within minutes as shown by scattering intensity measurements. At greater concentrations, the scattering intensity was approximately similar for all concentrations initially, but then decreased very slowly towards an apparent clustering equilibrium within two weeks. The mean hydrodynamic diameter of clusters, measured by dynamic light scattering, was initially around 1 μm for all concentrations greater than 5 mg/mL and then gradually reduced to around 0.4 μm at clustering equilibrium. At concentrations of 10 mg/mL and above, solid deposits were observed in toluene solutions when equilibrium was reached. 1H-NMR spectroscopy showed that the precipitate was high purity HTBHBC possessing a planar structure, while the liquid phase contained a mixture of planar HTBHBC and its non-planar derivatives, forming colloidal clusters. The results show that the clustering process of asphaltene mimics in toluene can be extremely slow and great care should be taken when preparing equilibrated solutions. We also showed that observations of the solid-liquid equilibrium and clustering behaviour can be strongly dependent on the molecular structure of the polyaromatic compounds found in natural asphaltenes, and the structural and compositional evolution of colloidal clusters following an initial dispersion of asphaltene mimics in solvents.

中文翻译：

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模拟天然沥青质的多环芳烃化合物的聚类行为

摘要 六叔丁基六邻六苯并可罗烯 (HTBHBC) 及其衍生物的聚类行为已被用作模拟天然沥青质的模型系统。我们使用光散射和 1H-NMR 光谱，辅以分子动力学模拟，来检查 HTBHBC 及其衍生物在甲苯和甲苯/庚烷混合物中的浓度范围。发现 HTBHBC 在甲苯中的分散性强烈依赖于其浓度。如散射强度测量所示，在低于 5 mg/mL 的浓度下，HTBHBC 似乎完全分散，并且在几分钟内达到聚类平衡。在更高的浓度下，所有浓度的散射强度最初大致相似，但随后在两周内非常缓慢地降低至明显的聚类平衡。对于大于 5 mg/mL 的所有浓度，通过动态光散射测量的团簇的平均流体动力学直径最初约为 1 μm，然后在团簇平衡时逐渐减小到约 0.4 μm。在 10 mg/mL 及以上的浓度下，当达到平衡时，在甲苯溶液中观察到固体沉积物。1H-NMR 谱表明沉淀为具有平面结构的高纯度 HTBHBC，而液相包含平面 HTBHBC 及其非平面衍生物的混合物，形成胶体簇。结果表明，沥青质模拟物在甲苯中的聚集过程可能非常缓慢，在制备平衡溶液时应格外小心。