Effect of Molecular Weight on the Capillary Absorption of Polymer Droplets
Effect of Molecular Weight on the Capillary Absorption of Polymer Droplets
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DOI：
10.1021/la300903w
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发表时间：
2012-07-10
期刊：
影响因子：
3.9
通讯作者：
Hendy, Shaun C.
中科院分区：
文献类型：
--
作者：
Dhondi, Srikanth;Pereira, G. G.;Hendy, Shaun C.
我们使用粗粒度分子动力学模拟和简单的分析模型研究小聚合物液滴进入不可润湿毛细管的毛细管吸收。对简单流体液滴的研究表明，毛细管过程取决于管与液滴半径的比率 [Willmottet al. 2014]。法拉第讨论，2010, 146, 233； Marmur J.胶体界面科学。 1988, 122, 209]。在这里，我们考虑聚合物液滴的吸收，并研究聚合物链长度对毛细管吸收过程的影响。我们的模拟表明，对于相同尺寸（半径）的液滴，临界管半径（低于该半径则没有吸收）随着构成液滴的聚合物链的长度而增加。我们提出了一个模型来解释这种效应，该模型结合了聚合物限制的熵惩罚，并发现该模型在数量上与模拟一致。我们还发现吸收动力学对聚合物链长度敏感。在某些情况下，在毛细管吸收期间观察到瞬时部分吸收状态，其中液滴部分进入管内和部分离开管。这种动态无法用广义的卢卡斯-沃什伯恩方法来解释。
We study capillary absorption of small polymer droplets into nonwettable capillaries using coarse-grained molecular dynamics simulations and a simple analytical model. Studies of droplets of simple fluids have revealed that the capillary process depends on the ratio of tube-to-droplet radii [Willmottet al. Faraday Discuss., 2010, 146, 233; Marmur J. Colloid Interface Sci. 1988, 122, 209]. Here we consider the absorption of droplets of polymers and study the effect of polymer chain length on the capillary absorption process. Our simulations reveal that for droplets of the same size (radius), the critical tube radius, below which there is no absorption, increases with the length of the polymer chains that constitute the droplets. We propose a model to explain this effect, which incorporates an entropic penalty for polymer confinement and find that this model agrees quantitatively with the simulations. We also find that the absorption dynamics is sensitive to the polymer chain length. In some cases during the capillary uptake transient partial absorption states, where the droplet is partially in and partially out of the tube, were observed. Such dynamics cannot be explained by a generalized Lucas-Washburn approach.