更坚固的海藻酸盐凝胶在微通道流中沉积更高效
Stiffer alginate gels deposit more efficiently in microchannel flows
AI总结：
本研究通过分析发现，流体中形成的凝胶刚性越高，沉积效率越高，同时剪切应力要求降低。
摘要：
交叉链接聚合物溶液在从液态状过渡到固态状材料时的行为决定了在多个应用中的成功或失败。稀释的聚合物溶液流动容易，而浓聚合物或交叉链接聚合物凝胶可能会堵塞孔隙、喷嘴或通道。我们最近描述了在流体中发生交叉链接时聚合物出现的第三类流动动力学现象：持续间歇性。当稀释的海藻酸盐溶液在Y形微流控交汇处遇到钙时，以恒定体积流速驱动时会形成持续且规律的凝胶沉积和消解模式。化学浓度和流速都控制着凝胶沉积和消解凝胶所需的临界剪切应力。在本工作中，我们提供了一个分析框架，以定量描述间歇行为，其原因是扩散驱动的沉积在高佩克数流中。拟合实验数据表明，更高的组分浓度导致更高效的沉积和更膨胀的凝胶。增加流速会增加沉积速率，但所形成的凝胶膨胀程度较低。消解发生在施加的剪切应力克服凝胶的粘附能或其屈服应力时。所需的剪切应力在组分浓度增加时降低。通过将分析分析结果与本体流变学测量结果相关联，我们发现沉积效率随着流中形成的凝胶的刚性增加而增加。更柔软的凝胶在消解前能承受更高的剪切应力。沉积效率和凝胶刚性在接近完全堵塞的流条件中增加。
英文摘要：
The behavior of cross-linking polymer solutions as they transition from liquid-like to solid-like material in flow determines success or failure in several applications. Dilute polymer solutions flow easily, while concentrated polymers or crosslinked polymer gels can clog pores, nozzles, or channels. We have recently described a third regime of flow dynamics in polymers that occurs when cross-linking happens during flow: persistent intermittency. When a dilute alginate solution meets calcium at a Y-shaped microfluidic junction, a persistent and regular pattern of gel deposition and ablation emerges when driven at a constant volumetric flow rate. Chemical concentrations and flow rate control both the gel deposition and critical shear stress required to ablate the adhered gel. In this work, we provide an analytical framework to quantitatively describe the intermittent behavior as resulting from diffusively driven deposition in a high Peclet number flow. Fitting the experimental data shows that higher component concentrations lead to more efficient deposition and more swollen gels. Increasing the flow rate increases the deposition rate, but the resulting gels are much less swollen. Ablation occurs when applied shear stresses overcome either the adhesive energy of the gel or its yield stress. The shear stress required at ablation decreases with increased component concentrations. By correlating the results of the analytical analysis with bulk rheology measurements, we find that deposition efficiency increases with the stiffness of the gel formed in flow. Softer gels withstand higher shear stresses before ablation. Both deposition efficiency and gel stiffness increase in flow conditions nearing complete clogging.
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