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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Length and Time-Dependent Rates in Diffusion-Controlled Reactions with ConjugatedPolymers
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Length and Time-Dependent Rates in Diffusion-Controlled Reactions with ConjugatedPolymers

机译：与共轭聚合物扩散控制的反应中的长度和时间依赖性速率

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Rate constants for diffusion-controlled reactions of solvated electrons with conjugated fluorene oligomers(oF) and polymers (pF) were measured in liquid tetrahydrofuran (THF). Preparative gel permeationchromatography (GPC) was used to separate the polyfluorenes into fractions having narrowed distributionsof lengths. Both oF and pF's were used in determinations of the attachment rate constants k_(inf)as a functionof length, where k_(inf)refers to the rate coefficients at long times where they are indeed constant. The resultsfind that in going from oF_1to pF_(133),k_(inf)increases by a factor of 16, which is much smaller than that of the133-fold increase in length. The extent of this increase and its change with length are in excellent agreementwith published theoretical models that describe diffusion to long thin objects as either prolate spheroids orone-dimensional arrays of spheres. As the concentration of polymer was increased, the effects of large transientterms in the rate constant were observed. As predicted by the Smoluchowski diffusion equation, withmodifications by more contemporary theorists, these transient effects are larger and persist to longer timesfor the larger molecules. For the longest molecule, pF_(133),k(t)increases by more than a decade at shorttimes.In that case, the "transient term" becomes dominant and the rate coefficient is approximately proportional tothe square of the effective reaction radius in contrast to the linear dependence usual for diffusional reactions.The size of these transient effects and their quantitative confirmation are unprecedented.
机译：在液态四氢呋喃（THF）中测量了溶剂化电子与共轭芴低聚物（oF）和聚合物（pF）的扩散控制反应的速率常数。制备凝胶渗透色谱法（GPC）用于将聚芴分离成长度分布窄的级分。 oF和pF都用于确定附着率常数k_（inf）作为长度的函数，其中k_（inf）指的是长时间它们确实恒定的速率系数。结果发现，从oF_1到pF_（133），k_（inf）增加了16倍，这比长度增加133倍要小得多。这种增加的程度及其随长度的变化与已发表的理论模型非常吻合，该理论模型描述了向长而细的物体的扩散是扁长球体或一维球体阵列。随着聚合物浓度的增加，观察到较大的瞬时项对速率常数的影响。正如Smoluchowski扩散方程所预测的那样，随着更多当代理论家的修改，这些瞬态效应更大，并且对于较大的分子而言，持续时间更长。对于最长的分子，pF_（133），k（t）在短时间内增加十倍以上。在这种情况下，“瞬变项”成为主导，速率系数与有效反应半径的平方成正比这些瞬态效应的大小及其定量确认是前所未有的。

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