Bridging Dynamics of Telechelic Polymers between Solid Surfaces
Bridging Dynamics of Telechelic Polymers between Solid Surfaces
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DOI：
10.1021/acs.macromol.7b01517
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发表时间：
2018-03-13
期刊：
影响因子：
5.5
通讯作者：
Larson, Ronald G.
中科院分区：
文献类型：
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作者：
Rezvantalab, Hossein;Larson, Ronald G.
我们采用布朗动力学模拟，结合前向通量采样和理论首次通过时间分析来描述远旋聚合物在固体表面（例如乳胶胶体）之间的环和桥之间的转换速率，远旋胶粘附在表面的强度足以使自由链非常罕见。结果表明，桥的形成速率可以用两个过程的时间组合来表示，即一端粘附体从靠近胶体表面的窄而深的结合中逃脱，以及链端在拉伸自由能的抑制下向另一个表面的较长距离运动。我们发现，当使用多头链来表示远螺旋聚合物时，较长距离的运动需要使用我们从Likhtman及其同事的工作中借鉴的多维首次通过时间分析，该分析最初用于描述一维重复管中的聚合物末端波动。根据这些成分，我们建立了环到桥和桥到环的过渡速率的解析表达式，作为每个聚合物珠数，间隙与平衡链长的比率以及末端贴纸与胶体/表面的结合能的函数。我们还建议，库恩步骤到弹簧的20比1映射可能允许分析应用于真实链，使分析适用于广泛的工业和生物过程。
We employ Brownian dynamics simulations combined with forward flux sampling and theoretical first passage time analyses to describe the rates of transitions between loops and bridges of telechelic polymers between solid surfaces representing e.g. latex colloids in the limit that the telechelic stickers bind strongly enough to the surfaces to make free chains very rare. It is shown that the bridge formation rate can be expressed by combining times for two processes, namely, the escape of one end sticker from the narrow-but-deep association well near the colloidal surface and the longer-range motion of the chain end to the other surface inhibited by stretching free energy. We find that when using multibead chains to represent the telechelic polymers, the longer-range motion requires use of a multidimensional first passage time analysis that we borrow from the work of Likhtman and co-workers, which was originally developed to describe polymer end fluctuations in a one-dimensional reptation tube. From these ingredients, we develop analytical expressions for the loop-to-bridge and bridge-to-loop transition rates as functions of the number of beads per polymer, the ratio of gap to the equilibrium chain length, and the end sticker association energy to the colloids/surfaces. We also suggest that a 20-to-1 mapping of Kuhn steps to springs may allow the analysis to be applied to real chains, rendering the analysis applicable to a broad range of industrial and biological processes.