The effect of hydroxyl functional groups and molar mass on the viscosity of non-crystalline organic and organic-water particles
The effect of hydroxyl functional groups and molar mass on the viscosity of non-crystalline organic and organic-water particles
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DOI：
10.5194/acp-17-8509-2017
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发表时间：
2017-07-13
影响因子：
6.3
通讯作者：
Bertram, Allan K.
中科院分区：
文献类型：
--
作者：
Grayson, James W.;Evoy, Erin;Bertram, Allan K.
本文研究了三种多元醇和三种正构烷烃在非晶态下的粘度。在干燥条件下研究了两种多元醇（2-甲基-1，4-丁二醇和1，2，3-丁三醇），研究了第三种多元醇（1，2，3，4-丁四醇）作为相对湿度（RH）的函数，包括在干燥条件下，研究了葡萄糖（葡萄糖），棉子糖和麦芽六糖作为RH的函数。在干燥条件下，多元醇的平均粘度范围为1.5 × 10（-1）至3.7 × 10（1）Pa·s，其中四醇的粘度最高。使用实验测定的数据和具有C-3至C-6碳骨架的烷烃、醇和多元醇的文献数据的组合，我们表明：（1）log（10）（粘度）和分子中羟基的数目，（2）平均而言，加入一个OH基团使粘度增加约22至45倍，（3）粘度对添加一个OH基团的敏感性不是分子中已经存在的OH官能团的数目（至多三个OH基团）的强函数，和（4）当分子具有多于三个OH基团时，观察到更高的敏感性。这里报道的1，2，3，4-丁烷四醇颗粒的粘度低于以前报道的使用气溶胶光镊的测量值，需要进行额外的研究来解决这些差异。对于糖颗粒，在30%RH下，随着摩尔质量从180增加到342 g mol（-1），粘度增加约25个数量级，并且在80%RH下，随着摩尔质量从180增加到991 g mol（-1），粘度增加约4-5个数量级。这些结果表明，在大气中的二次有机气溶胶（SOA）的高度氧化的化合物的低聚反应可能会导致大的粘度增加，并可能至少部分负责在一些SOA中观察到的高粘度。最后，使用两种定量结构-性质关系模型（Sastri和Rao，1992; Marrero-Morejon和Pardillo-Fontdevila，2000）预测具有C-3-C-6碳骨架的烷烃、醇和多元醇的粘度。这两种模型显示出相当好的协议与测量的烷烃，醇，和多元醇的粘度在这里研究的情况下，除了六醇，其粘度是低估了1-3个数量级的每个模型。
The viscosities of three polyols and three saccharides, all in the non-crystalline state, have been studied. Two of the polyols (2-methyl-1,4-butanediol and 1,2,3-butanetriol) were studied under dry conditions, the third (1,2,3,4-butanetetrol) was studied as a function of relative humidity (RH), including under dry conditions, and the saccharides (glucose, raffinose, and maltohexaose) were studied as a function of RH. The mean viscosities of the polyols under dry conditions range from 1.5 x 10(-1) to 3.7 x 10(1) Pa s, with the highest viscosity being that of the tetrol. Using a combination of data determined experimentally here and literature data for alkanes, alcohols, and polyols with a C-3 to C-6 carbon backbone, we show (1) there is a near-linear relationship between log(10) (viscosity) and the number of hydroxyl groups in the molecule, (2) that on average the addition of one OH group increases the viscosity by a factor of approximately 22 to 45, (3) the sensitivity of viscosity to the addition of one OH group is not a strong function of the number of OH functional groups already present in the molecule up to three OH groups, and (4) higher sensitivities are observed when the molecule has more than three OH groups. Viscosities reported here for 1,2,3,4-butanetetrol particles are lower than previously reported measurements using aerosol optical tweezers, and additional studies are required to resolve these discrepancies. For saccharide particles at 30% RH, viscosity increases by approximately 25 orders of magnitude as molar mass increases from 180 to 342 g mol(-1), and at 80% RH, viscosity increases by approximately 4-5 orders of magnitude as molar mass increases from 180 to 991 g mol(-1). These results suggest oligomerization of highly oxidized compounds in atmospheric secondary organic aerosol (SOA) could lead to large increases in viscosity, and may be at least partially responsible for the high viscosities observed in some SOA. Finally, two quantitative structure-property relationship models (Sastri and Rao, 1992; Marrero-Morejon and Pardillo-Fontdevila, 2000) were used to predict the viscosity of alkanes, alcohols, and polyols with a C-3-C-6 carbon backbone. Both models show reasonably good agreement with measured viscosities for the alkanes, alcohols, and polyols studied here except for the case of a hexol, the viscosity of which is underpredicted by 1-3 orders of magnitude by each of the models.