Department of Chemistry and Center for Biologically Inspired Materials and Material Systems, Duke University, Durham, North Carolina 27708-0346, United States.
J Am Chem Soc. 2010 Nov 17;132(45):15936-8. doi: 10.1021/ja108429h. Epub 2010 Oct 26.
Single-molecule force spectroscopy is used to observe the irreversible extension of a gem-dibromocyclopropane (gDBC)-functionalized polybutadiene under tension, a process akin to polymer necking at a single-molecule level. The extension of close to 28% in the contour length of the polymer backbone occurs at roughly 1.2 nN (tip velocity of 3 μm/s) and is attributed to the force-induced isomerization of the gDBCs into 2,3-dibromoalkenes. The rearrangement represents a possible new mechanism for localized stress relief in polymers and polymer networks under load, and the quantification of the force dependency provides a benchmark value for further studies of mechanically triggered chemistry in bulk polymers.
单分子力谱用于观察张力下的双溴环丙烷（gDBC）官能化聚丁二烯的不可逆延伸，这一过程类似于单分子水平上的聚合物颈缩。聚合物主链的长度接近 28%的延伸发生在大约 1.2 nN（尖端速度为 3 μm/s），这归因于 gDBC 异构化为 2,3-二溴烯烃的力诱导。这种重排代表了在负载下聚合物和聚合物网络中局部应力释放的一种可能的新机制，力依赖性的定量为进一步研究本体聚合物中机械触发的化学提供了基准值。
