Designing Stress-Adaptive Dense Suspensions Using Dynamic Covalent Chemistry.
Designing Stress-Adaptive Dense Suspensions Using Dynamic Covalent Chemistry.
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DOI：
10.1021/acs.macromol.2c00603
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发表时间：
2022-08-09
期刊：
影响因子：
5.5
通讯作者：
Jaeger, Heinrich M.
中科院分区：
文献类型：
--
作者：
Jackson, Grayson L.;Dennis, Joseph M.;Dolinski, Neil D.;van der Naald, Michael;Kim, Hojin;Eom, Christopher;Rowan, Stuart J.;Jaeger, Heinrich M.
致密悬浮液的非牛顿行为是其在技术和工业应用中的核心，并且产生于动态适应施加剪切的颗粒-颗粒接触网络。本文报道的研究旨在探索如何利用颗粒和聚合物溶剂之间的动态共价化学来定制这种应力适应接触网络，从而导致它们不同寻常的流变行为。具体而言，采用室温动态thia-Michael键合理调整聚合物溶剂的平衡常数（Keq）到粒子界面。结果表明，低Keq会导致剪切变薄，而高Keq会产生抗触变性，这是一种罕见的现象，粘度随着剪切时间的增加而增加。提出Keq的增加增加了颗粒表面的聚合物接枝密度，抗触变性主要是由于聚合物接枝/溶剂与颗粒表面的部分脱键以及颗粒之间聚合物桥的形成。因此，动态共价化学的实现提供了一种新的分子处理方法，通过引入可编程的时间依赖性来调整悬浮液的宏观流变性。这些研究为吸能材料打开了大门，这些吸能材料不仅可以感知机械输入并根据时间或剪切速率调节其耗散，而且还可以根据需要在这两种模式之间切换。
The non-Newtonian behaviors of dense suspensions are central to their use in technological and industrial applications and arise from a network of particle–particle contacts that dynamically adapt to imposed shear. Reported herein are studies aimed at exploring how dynamic covalent chemistry between particles and the polymeric solvent can be used to tailor such stress-adaptive contact networks, leading to their unusual rheological behaviors. Specifically, a room temperature dynamic thia-Michael bond is employed to rationally tune the equilibrium constant (Keq) of the polymeric solvent to the particle interface. It is demonstrated that low Keq leads to shear thinning, while high Keq produces antithixotropy, a rare phenomenon where the viscosity increases with shearing time. It is proposed that an increase in Keq increases the polymer graft density at the particle surface and that antithixotropy primarily arises from partial debonding of the polymeric graft/solvent from the particle surface and the formation of polymer bridges between particles. Thus, the implementation of dynamic covalent chemistry provides a new molecular handle with which to tailor the macroscopic rheology of suspensions by introducing programmable time dependence. These studies open the door to energy-absorbing materials that not only sense mechanical inputs and adjust their dissipation as a function of time or shear rate but also can switch between these two modalities on demand.
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DOI：
10.1007/978-1-4939-2065-5_6
发表时间：
2015-01-01
期刊：
COMPLEX FLUIDS IN BIOLOGICAL SYSTEMS: EXPERIMENT, THEORY, AND COMPUTATION
影响因子：
--
作者：
Ewoldt, Randy H.;Johnston, Michael T.;Caretta, Lucas M.
通讯作者：
Caretta, Lucas M.
影响因子：
4.6
作者：
Chakma, Progyateg;Possarle, Luiz Henrique Rodrigues;Konkolewicz, Dominik
通讯作者：
Konkolewicz, Dominik
影响因子：
4.9
作者：
Borsley, Stefan;Kay, Euan R.
通讯作者：
Kay, Euan R.
影响因子：
3.3
作者：
Frith, WJ;dHaene, P;Mewis, J
通讯作者：
Mewis, J
影响因子：
5.5
作者：
FitzSimons, Thomas M.;Oentoro, Felicia;Rosales, Adrianne M.
通讯作者：
Rosales, Adrianne M.