Colloidal Particles that Rapidly Change Shape via Elastic Instabilities
Colloidal Particles that Rapidly Change Shape via Elastic Instabilities
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DOI：
10.1002/smll.201502198
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发表时间：
2015-12-02
期刊：
影响因子：
13.3
通讯作者：
Braun, Paul V.
中科院分区：
文献类型：
--
作者：
Epstein, Eric;Yoon, Jaewon;Braun, Paul V.
报告了 pH 响应胶体颗粒的制造和特性，其形状变化迅速（小于 200 毫秒），几乎独立于触发其驱动的 pH 改变物质的扩散，并且比其布朗运动快得多。这些颗粒具有机械双稳态，正如它们的滞后形状响应所揭示的那样。有限元分析 (FEA) 显示机械滞后和双稳态源自胶体的球面曲率。包含胶体颗粒的双层聚合物的机械表征表明，粘弹性松弛在限制形状转换速率方面起着不可忽视的作用；然而，从 FEA 模拟获得的能量景观表明，通过调整组成聚合物层的弹性模量和厚度，可以制造此处所示尺寸的微粒，使其在快至 1 秒的时间尺度上启动。
The fabrication and properties of pH-responsive colloidal particles are reported, which change shape rapidly (less than 200 ms), nearly independent of the diffusion of the pH altering species that trigger their actuation, and far more rapid than their Brownian motion. These particles are mechanically bistable, as revealed by their hysteretic shape response. Finite element analysis (FEA) shows that mechanical hysteresis and bistability derives from the colloids' spherical curvature. Mechanical characterization of the bilayered polymers comprising the colloidal particles shows that viscoelastic relaxation plays a non-negligible role in limiting the shape switching rate; however, energy landscapes obtained from FEA simulations suggest that by tuning the elastic moduli and thicknesses of the constituent polymer layers, microparticles of the size shown here may be fabricated to actuate on timescales as fast as 1 s.