Dynamic Reconfiguration of Compressed 2D Nanoparticle Monolayers
Dynamic Reconfiguration of Compressed 2D Nanoparticle Monolayers
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DOI：
10.1021/acsnano.1c09853
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发表时间：
2022-04-26
期刊：
影响因子：
17.1
通讯作者：
Russell, Thomas P.
中科院分区：
文献类型：
--
作者：
Kim, Paul Y.;Gao, Yige;Russell, Thomas P.
通过在单颗粒水平上进行的原位扫描电子显微镜，在液体表面实时成像被堵塞或几乎被堵塞的球形纳米颗粒的吉布斯单层。当纳米颗粒的面积分数高于二维结晶开始时，在逐步的面积压缩后，可以看到可移动的聚合物包覆颗粒的结构重组。当压缩较小时，在晶界观察到位错附近的缓慢剪切和重新构型的纳米颗粒结合。在更大的尺度上，域随着相关但高度间歇性的运动旋转到注册处而增长。同时，单层中部的面密度增加。当压缩较大时，堵塞的单层会出现皱折和凸起等面外变形。由于其较大的界面结合能，二维可移动的纳米粒子很少(如果有的话)返回到液体亚相。压缩足够长的时间(几个小时或更长时间)，单分子膜转变为固体纳米颗粒薄膜，这表明它们在随后的区域扩张时发生破裂和局部破裂。这些观察提供了对一个简单模型系统的动力学的机械洞察，该模型系统在响应机械应力的情况下经历干扰/非干扰。
A Gibbs monolayer of jammed, or nearly jammed, spherical nanoparticles was imaged at a liquid surface in real time by in-situ scanning electron microscopy performed at the single-particle level. At nanoparticle areal fractions above that for the onset of two-dimensional crystallization, structural reorganizations of the mobile polymer-coated particles were visualized after a stepwise areal compression. When the compression was small, slow shearing near dislocations and reconfigured nanoparticle bonding were observed at crystal grain boundaries. At larger scales, domains grew as they rotated into registry by correlated but highly intermittent motions. Simultaneously, the areal density in the middle of the monolayer increased. When the compression was large, the jammed monolayers exhibited out-of-plane deformations such as wrinkles and bumps. Due to their large interfacial binding energy, few (if any) of the two-dimensionally mobile nanoparticles returned to the liquid subphase. Compressed long enough (several hours or more), monolayers transformed into solid nanoparticle films, as evidenced by their cracking and localized rupturing upon subsequent areal expansion. These observations provide mechanistic insights into the dynamics of a simple model system that undergoes jamming/unjamming in response to mechanical stress.