Using hydrodynamic simulations, we study the single polymers flowing through model porous media (close-packed colloidal crystal). In good solvent or high flow rates, the polymer transport is similar to gel electrophoresis, with size-dependent sieving for $L_c/L\lesssim 1$ and size-independent biased reptation for $L_c/L\gtrsim 1$ ($L_c$ is the polymer contour length and $L$ is the diameter of colloids forming the porous media). Importantly, in bad solvent and low flow rates, the polymers show an extra window of size-dependent velocity for $1\lesssim L_c/L\lesssim 2$, where the polymer transport is controlled by a globule-stretch transition at pore throats, and the transport velocity is much slower than reptation.

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塌陷的聚合物流过多孔介质时出现的慢速动力学

使用流体动力学模拟，我们研究了流经模型多孔介质（密堆积胶体晶体）的单种聚合物。在良好的溶剂或高流速下，聚合物的传输类似于凝胶电泳，其中大小相关的筛分用于${\mathrm{大号}}_C/\mathrm{大号}\lesssim \mathrm{1个}$ 和大小无关的偏见 ${\mathrm{大号}}_C/\mathrm{大号}\gtrsim \mathrm{1个}$ （${\mathrm{大号}}_C$ 是聚合物轮廓长度， $\mathrm{大号}$是形成多孔介质的胶体直径）。重要的是，在不良溶剂和低流速下，聚合物对$\mathrm{1个}\lesssim {\mathrm{大号}}_C/\mathrm{大号}\lesssim \mathrm{2个}$，其中聚合物的传输受孔喉处的小球－拉伸过渡控制，并且传输速度比复制慢得多。