Flow-induced gelation of microfiber suspensions
Flow-induced gelation of microfiber suspensions
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DOI：
10.1073/pnas.1710927114
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发表时间：
2017-10-10
影响因子：
11.1
通讯作者：
Stone, Howard A.
中科院分区：
文献类型：
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作者：
Perazzo, Antonio;Nunes, Janine K.;Stone, Howard A.
纤维悬浮液的流动行为已被广泛研究，特别是在稀浓度和刚性纤维的限制下;然而，在另一个极端，在悬浮液浓缩和纤维高度柔性的情况下，对流动性质的了解要少得多。我们使用微流体方法来生产高纵横比，柔性微纤维的均匀浓缩悬浮液，我们证明了这种微纤维悬浮液的剪切增稠和凝胶化行为，据我们所知，以前没有报道过。通过流变学的手段，我们表明，流动的悬浮液触发不可逆的形成的拓扑缠结的纤维，导致在一个纠缠的水填充网络。这种现象表明，柔性纤维悬浮液可以用来生产一种新的家庭的流动诱导凝胶材料，如多孔水凝胶。这些流动性质的重要结果是微纤维悬浮液可通过针注射，其可作为水凝胶直接从针挤出，而无需任何化学反应或进一步处理。此外，我们表明，这种纤维水凝胶是一种软，粘弹性，屈服应力材料。
The flow behavior of fiber suspensions has been studied extensively, especially in the limit of dilute concentrations and rigid fibers; at the other extreme, however, where the suspensions are concentrated and the fibers are highly flexible, much less is understood about the flow properties. We use a microfluidic method to produce uniform concentrated suspensions of high aspect ratio, flexible microfibers, and we demonstrate the shear thickening and gelling behavior of such microfiber suspensions, which, to the best of our knowledge, has not been reported previously. By rheological means, we show that flowing the suspension triggers the irreversible formation of topological entanglements of the fibers resulting in an entangled water-filled network. This phenomenon suggests that flexible fiber suspensions can be exploited to produce a new family of flow-induced gelledmaterials, such as porous hydrogels. A significant consequence of these flow properties is that the microfiber suspension is injectable through a needle, from which it can be extruded directly as a hydrogel without any chemical reactions or further treatments. Additionally, we show that this fiber hydrogel is a soft, viscoelastic, yield-stress material.