Densities, Viscosities, and Self-Diffusion Coefficients of Ethylene Glycol Oligomers
Densities, Viscosities, and Self-Diffusion Coefficients of Ethylene Glycol Oligomers
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DOI：
10.1021/acs.jced.1c00101
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发表时间：
2021-05-05
期刊：
影响因子：
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通讯作者：
Buntkowsky, Gerd
中科院分区：
文献类型：
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作者：
Hoffmann, Markus M.;Horowitz, Rachel H.;Buntkowsky, Gerd
聚乙二醇（PEG）作为一种可替代的绿色溶剂在化学合成和加工中越来越受到关注。本报告提供了从293.15 K到358.15 K的密度和粘度数据以及从298.15 K到358.15 K的PEG从二乙二醇到九乙二醇的低聚物的自扩散系数数据。通过从测量系列外推获得结果，其中故意以几个增量添加水（PEG中最常见的杂质）。所得到的结果进行了仔细比较，文献数据，这是广泛使用的密度和粘度，只有较低的低聚物。密度被发现是线性依赖于所有研究的低聚物的温度。粘度和自扩散系数的温度依赖性显示在所研究的温度范围内，从Arcidius方程只有轻微的偏差。从粘度数据得到的活化能与从自扩散系数数据得到的活化能吻合得很好，并且似乎相对于PEG低聚物中的环氧乙烷重复单元的数目线性依赖。这种线性结合的观察，即指前因子似乎是相同的所有研究的低聚物可以作为一种工具，以估计粘度和自扩散系数较高的低聚物在研究的温度范围内。低聚物的密度都落在一个相当窄的范围内，没有明显的趋势，在同源系列。
Polyethylene glycol (PEG) is gaining interest as an alternative green solvent in chemical synthesis and processing. This report presents density and viscosity data from 293.15 K to 358.15 K as well as self-diffusion coefficient data from 298.15 K to 358.15 K for oligomers of PEG from di- to nonaethylene glycol. The results were obtained by extrapolation from measurement series where water, the most common impurity in PEGs, was intentionally added in several increments. The obtained results are carefully compared to literature data, which are widely available only for density and viscosity, and only for the lower oligomers. Densities are found to be linearly dependent on temperatures for all studied oligomers. The temperature dependence of viscosity and self-diffusion coefficients show only slight deviations from the Arrhenius equation over the investigated temperature range. The activation energies obtained from the viscosity data agree well with the activation energies from the self-diffusion coefficient data and appear to be linearly dependent with respect to the number of ethylene oxide repeat units in the PEG oligomer. This linearity combined with the observation that the pre-exponential factor appears to be the same for all studied oligomers may serve as a tool to estimate viscosities and self-diffusion coefficients for higher oligomers within the investigated temperature range. The densities of the oligomers all fall within a rather narrow range without a clear trend in homologous series.