Stopped-Flow Dynamics Study on the Escape Behavior of Polyelectrolyte Macromolecules from Microgels: The Influence of the Path Length and Size
Stopped-Flow Dynamics Study on the Escape Behavior of Polyelectrolyte Macromolecules from Microgels: The Influence of the Path Length and Size
复制标题
聚电解质大分子从微凝胶中逃逸行为的停流动力学研究：光程长度和尺寸的影响
DOI：
10.1021/acs.langmuir.0c00738
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发表时间：
2020
期刊：
影响因子：
3.9
通讯作者：
Yin Jun
中科院分区：
文献类型：
--
作者：
Zha Jie-Cheng;Mao Xiao-Xu;Hu Shou-Kui;Shang Ke;Yin Jun
采用成熟的乳液聚合方法制备了几种单分散的聚（2-乙烯基吡啶）-聚（N-异丙基丙烯酰胺）（P2 VP-PNIPAM）微凝胶，包括P2 VP核（非交联）和PNIPAM壳（交联）。用pH跃变停流装置研究了线性P2 VP链在多孔PNIPAM层中的快速逃逸行为（扩散过程）。依赖于时间的动态轨迹（对应于散射光强度）在几秒的初始时间尺度下下降，然后达到表观平衡，证实了P2 VP链从微凝胶中的有效逃逸。与文献报道的结果相比，这种加速的逃逸过程是由于酸性条件下P2 VP部分质子化引起的内部电荷排斥力急剧增加所致。这些动力学轨迹的单指数拟合得到的特征弛豫时间依赖于最终的pH值，平衡温度，壳厚度（路径长度），和交联密度（网格大小）。我们相信，这项工作可以提供一个有效的方法来研究受阻扩散，特别是初始快速扩散阶段。不仅如此，该模型还可以为膜分离、胞内蛋白质或大分子物质的胞吐现象等实际应用提供理论指导。
We reported the fabrication of several monodispersed poly(2-vinyl pyridine)-poly(N-isopropylacrylamide) (P2VP-PNIPAM) microgels including the P2VP core (non-cross-linked) and PNIPAM (cross-linked) shell by mature emulsion polymerization. The fast escape behavior (diffusion process) of linear P2VP chains through a porous PNIPAM layer was investigated by a pH jump stopped-flow apparatus. The time-dependent dynamic traces (corresponding to the scattered light intensity) decreased at the initial timescale of several seconds and then reached an apparent equilibrium, confirming the efficient escape of P2VP chains from microgels. Compared with the previously reported literature, such an accelerated escape process resulted from the sharply increased internal charge repulsive force caused by the protonation of P2VP moieties under acidic conditions. The obtained characteristic relaxation times by single exponential fitting of these kinetic traces were dependent on the final pH values, equilibrium temperatures, shell thickness (path length), and cross-linking density (mesh size). We believe that this work can provide an efficient way to investigate hindered diffusion, especially the initial rapid diffusion stage. Not only that, the proposed model can also provide theoretical guidance to some practical applications, such as membrane separation and the exocytosis phenomenon of intracellular proteins or macromolecular substances.