论文标题
从Rheo-射仪光谱揭示的单羟基醇中Debye松弛的分子机制
Molecular mechanism of the Debye relaxation in monohydroxy alcohols revealed from rheo-dielectric spectroscopy
论文作者
论文摘要
首次采用了类风湿光谱，以研究外部剪切对模型单羟基醇（即2-乙基-1-己醇（2E1H））的脱甲基弛豫的影响。剪切变形导致结构弛豫，Debye松弛和2E1H的末端弛豫的强大加速度。此外，剪切诱导的结构放松时间的减少，tau_alpha，与debye时间，tau_d和末端流动时间（Tau_f）的缩放尺寸二次缩放，这表明tau_d*tau_d*tau_d〜tau_dau_alpha的关系。进一步的分析表明，tau_d*tau_d/tau_alpha的2e1h遵循Arrhenius温度依赖性，该依赖性非常适用于许多其他具有不同分子尺寸，结构和酒精类型的单羟基醇。这些结果无法通过盛行的瞬态链模型来理解，并提出H键断裂促进了促进的亚苏普拉米分子的重新定位，这是单羟基醇的Debye松弛的起源，类似于分子机制，用于终末放松。
Rheodielectric spectroscopy is employed, for the first time, to investigate the effect of external shear on the Debyelike relaxation of a model monohydroxy alcohol, i.e., the 2-ethyl-1-hexanol (2E1H). Shear deformation leads to strong acceleration in the structural relaxation, the Debye relaxation, and the terminal relaxation of 2E1H. Moreover, the shear-induced reduction in structural relaxation time, tau_alpha, scales quadratically with that of Debye time, tau_D, and the terminal flow time, tau_f, suggesting a relationship of tau_D*tau_D~tau_alpha. Further analyses reveal tau_D*tau_D/tau_alpha of 2E1H follows Arrhenius temperature dependence that applies remarkably well to many other monohydroxy alcohols with different molecular sizes, architectures, and alcohol types. These results cannot be understood by the prevailing transient chain model and suggest a H-bonding breakage facilitated sub-supramolecular reorientation as the origin of Debye relaxation of monohydroxy alcohols, akin to the molecular mechanism for the terminal relaxation of unentangled living polymers
