Negative interfacial energies of dynamic polymer brush interfaces: a discussion of the free energy balance
Negative interfacial energies of dynamic polymer brush interfaces: a discussion of the free energy balance
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动态聚合物刷界面的负界面能：自由能平衡的讨论
DOI：
10.1038/s41428-023-00789-2
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发表时间：
2023
期刊：
影响因子：
2.8
通讯作者：
Yokoyama Hideaki
中科院分区：
文献类型：
--
作者：
Saito Masayuki;Ito Kohzo;Yokoyama Hideaki
界面能是描述界面性质的重要物理参数。然而，量化聚合物-液体界面的界面能是极其困难的，因为许多聚合物在接触液体时会发生重构。动态聚合物笔刷是重建的曲面。当含有两亲性嵌段共聚物的疏水弹性体与水接触时，共聚物在弹性体-水界面自发分离，形成一种称为动态聚合物刷子的亲水刷子。我们以前通过测量漂浮在水面上的超薄方形弹性体膜的变形成功地分析了动态聚合物刷界面的界面能。然而，定量仍然是有争议的，因为使用的是整体弹性体片的弹性模数，而不是超薄的弹性体膜。在这项研究中，我们使用最近通过水上薄膜拉伸测试测量的超薄膜模数来重新分析动态聚合物刷子系统的界面能。对于高密度拉伸电刷体系，观察到较大的负界面能。对漂浮在水面上的动态聚合物刷体系的自由能平衡进行了计算，计算结果验证了动态聚合物刷的显著特征--负界面能。
Interfacial energy is an important physical parameter for describing interfacial properties. However, quantifying the interfacial energy of a polymer–liquid interface is extremely difficult because numerous polymers reconstruct when exposed to liquids. A dynamic polymer brush is a reconstructed surface. When a hydrophobic elastomer containing amphiphilic block copolymers comes into contact with water, the copolymers spontaneously segregate at the elastomer–water interface to form a hydrophilic brush known as a dynamic polymer brush. We previously succeeded in analyzing the interfacial energy of a dynamic polymer brush interface by measuring the deformation of an ultrathin square elastomer film floating on water. However, the quantitativity remains debatable because the elastic modulus of a bulk elastomer sheet, rather than an ultrathin elastomer film, was used. In this study, we reanalyze the interfacial energy of a dynamic polymer brush system using the ultrathin-film modulus, which we recently measured via a film-on-water tensile test. Large negative interfacial energy was observed for the system of high-density stretched brushes. The free energy balance for the dynamic polymer brush system floating on water was calculated, and results validated the negative interfacial energy, which is a distinctive feature of dynamic polymer brushes.