Spinodal stratification in ultrathin micellar foam films
Spinodal stratification in ultrathin micellar foam films
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超薄胶束泡沫薄膜中的旋节线分层
DOI：
10.1039/c8me00102b
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发表时间：
2019
影响因子：
3.6
通讯作者：
Sharma, Vivek
中科院分区：
文献类型：
--
作者：
Yilixiati, Subinuer;Wojcik, Ewelina;Zhang, Yiran;Sharma, Vivek
我们报告了一种迄今未被报道的胶束泡沫膜排水和破裂机制的发现，这为理解和控制无处不在的泡沫的稳定性、寿命和性能提供了未知的机会。众所周知，超薄胶束泡沫塑料薄膜呈现分层现象，表现为逐步变薄和厚度不同的薄-厚平坦区域共存，厚度不同的纳米级步长等于胶束间距离。层结通常包括更薄、更暗、圆形区域或更厚、更亮的台地的自发形成和生长。从力学上讲，聚合物薄膜的磁区扩展与孔洞生长相似，其成核和生长机制可以通过考虑由厚度相关的振荡自由能产生的亚稳态来描述。脱湿聚合物薄膜偶尔会通过调幅节脱湿而分成厚和薄两个区域，形成相互连接的网状结构。然而，对于独立的薄膜，形成厚-薄调幅图案的报道从未被报道过。在这一贡献中，我们表明，由于限制诱导胶束分层而产生的对自由能的依赖于厚度的振荡贡献，可以通过经历我们称为调幅节层积的过程来驱动这种厚-薄区域的形成。我们使用ITOM(干涉测量数字成像光学显微镜)协议来可视化和表征纳米级厚度的变化和转变，以获得精确的独立膜厚度图。我们发现垂直泡沫膜中的蒸发和强化排水在驱动这一过程中起着关键作用，无论是在单一泡沫膜中还是在整体泡沫膜中都可以发生调幅节状分层。
We report the discovery of a hitherto unreported mechanism of drainage and rupture of micellar foam films that presents unexplored opportunities for understanding and controlling the stability, lifetime and properties of ubiquitous foams. It is well-known that ultrathin micellar foam films exhibit stratification, manifested as stepwise thinning and coexistence of thin–thick flat regions that differ in thickness by a nanoscopic step size equal to the intermicellar distance. Stratification typically involves the spontaneous formation and growth of thinner, darker, circular domains or thicker, brighter mesas. Mechanistically, domain expansion appears similar to hole growth in polymer films undergoing dewetting by nucleation and growth mechanism that can be described by considering metastable states resulting from a thickness-dependent oscillatory free energy. Dewetting polymer films occasionally phase separate into thick and thin regions forming an interconnected, network-like morphology by undergoing spinodal dewetting. However, the formation of thick–thin spinodal patterns has never been reported for freestanding films. In this contribution, we show that the thickness-dependent oscillatory contribution to free energy that arises due to confinement-induced layering of micelles can drive the formation of such thick-thin regions by undergoing a process we term as spinodal stratification. We visualize and characterize the nanoscopic thickness variations and transitions by using IDIOM (interferometry digital imaging optical microscopy) protocols to obtain exquisite thickness maps of freestanding films. We find that evaporation and enhanced drainage in vertical films play a critical role in driving the process, and spinodal stratification can occur in both single foam films and in bulk foam.
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DOI：
10.1021/acs.langmuir.8b01010
发表时间：
2018-06
期刊：
Langmuir : the ACS journal of surfaces and colloids
影响因子：
--
作者：
Yiran Zhang;Vivek Sharma
通讯作者：
Yiran Zhang;Vivek Sharma
影响因子：
--
作者：
J. Perrin
通讯作者：
J. Perrin
非离子胶束存在下泡沫膜的排水
影响因子：
9.9
作者：
A. Nikolov;D. Wasan;N. Denkov;P. Kralchevsky;I. Ivanov
通讯作者：
I. Ivanov
DOI：
10.1021/la047178
发表时间：
2005
期刊：
Langmuir : the ACS journal of surfaces and colloids
影响因子：
--
作者：
S. Berg;Eric A. Adelizzi;S. Troian
通讯作者：
S. Troian
胶束独立式薄膜中纳米脊的形成和分层动力学。
DOI：
10.1021/acs.langmuir.7b01871
发表时间：
2017
期刊：
Langmuir : the ACS journal of surfaces and colloids
影响因子：
--
作者：
Yiran Zhang;Vivek Sharma
通讯作者：
Vivek Sharma