How a Chain Can Be Extended While Its Bonds Are Compressed
How a Chain Can Be Extended While Its Bonds Are Compressed
复制标题
链如何在键被压缩的情况下延伸
DOI：
10.1021/acsmacrolett.3c00097
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发表时间：
2023
影响因子：
7.015
通讯作者：
Rubinstein, Michael
中科院分区：
文献类型：
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作者：
Sapir, Liel;Brock, James;Chen, Danyang;Liao, Qi;Panyukov, Sergey;Rubinstein, Michael
延伸聚合物链导致正链张力fch，这主要是由于构象限制。然而，在单个键的水平上，张力fb要么是负的，要么是正的，取决于链张力和体压。通常，链和键张力被假定为直接相关。然而，在特定系统中，这种依赖性可能不是直观的，其中fch增加而efb减少;即，整个链被伸展而键被压缩。具体地，增加聚合物刷的接枝密度导致链沿垂直于接枝表面的方向沿着延伸，同时下面的键被压缩。类似地，在压缩聚合物网络时，在“自由”方向上取向的链的延伸增加，而它们的键变得更加压缩。我们在分子动力学模拟中证明了这种现象，并解释了这样一个事实，即压力的贡献fbis占主导地位的网络变形和刷接枝密度的范围很广。
Extending polymer chains results in a positive chain tension,fch, primarily due to conformational restrictions. At the level of individual bonds, however, tension,fb, is either negative or positive and depends on both chain tension and bulk pressure. Typically, the chain and bond tension are assumed to be directly related. In specific systems, however, this dependence may not be intuitive, wherebyfchincreases whilefbdecreases; i.e., the entire chain is extended while bonds are compressed. Specifically, increasing the grafting density of a polymer brush results in chain extension along the direction perpendicular to the grafting surface while the underlying bonds are compressed. Similarly, upon compression of polymer networks, the extension of chains oriented in the “free” direction increases while their bonds are getting more compressed. We demonstrate this phenomenon in molecular dynamics simulations and explain it by the fact that the pressure contribution tofbis dominant over a wide range of network deformations and brush grafting densities.