Single polymer dynamics in an elongational flow
Single polymer dynamics in an elongational flow
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DOI：
10.1126/science.276.5321.2016
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发表时间：
1997-06-27
期刊：
影响因子：
56.9
通讯作者：
Chu, S
中科院分区：
文献类型：
--
作者：
Perkins, TT;Smith, DE;Chu, S
利用荧光标记的DNA分子观察了聚合物在空间均匀速度梯度中的拉伸行为，确定了分子拉伸的概率分布与时间和应变率的函数关系。虽然有些分子达到了稳定状态，但平均延伸并没有，即使在下面的流体元素发生了类似300倍的扭曲之后。在最高的应变速率，不同的构象形状与不同的动力学进行了观察，有相当大的变化，在拉伸的开始，和哑铃形状的链拉伸比折叠的更迅速。随着应变速率的增加，链不与流体元件一起变形。稳态延伸可以用一个模型来描述，该模型由两个珠子通过弹簧连接组成，代表蠕虫状链的熵弹性，但平均动力学不能。
The stretching of individual polymers in a spatially homogeneous velocity gradient was observed through use of fluorescently labeled DNA molecules, The probability distribution of molecular extension was determined as a function of lime and strain rate. Although some molecules reached steady state, the average extension did not, even after a similar to 300-fold distortion of the underlying fluid element. At the highest strain rates, distinct conformational shapes with differing dynamics were observed, There was considerable variation in the onset of stretching, and chains with a dumbbell shape stretched more rapidly than folded ones. As the strain rate was increased, chains did not deform with the fluid element. The steady-state extension can be described by a model consisting of two beads connected by a spring representing the entropic elasticity of a worm-like chain, but the average dynamics cannot.