Kato Sota, Aoki Daisuke, Oikawa Kazusato, Tsuchiya Kousuke, Numata Keiji, Otsuka Hideyuki
Department of Chemical Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
ACS Macro Lett. 2021 May 18;10(5):623-627. doi: 10.1021/acsmacrolett.1c00185. Epub 2021 May 3.
To visualize and simultaneously quantify the necking behavior of crystalline polymer films during uniaxial stretching, tetraarylsuccinonitrile (TASN) moieties were introduced into polymers at the center of the main chain. TASN can produce a relatively stable radical that emits yellow fluorescence in response to mechanical stress. During the uniaxial elongation test of the TASN-centered crystalline polymers, the yellow fluorescence derived from the dissociated TASN radicals was used for microscale observations that showed the orientation of the polymer chains in the stretching direction. Furthermore, by comparing the radical generation in linear and star-shaped TASN-centered crystalline polymers during their tensile deformation, we found that the TASN dissociation ratio is higher in the star-shaped polymer, which has more chains connected to the lamellar crystal. Thus, the microforces generated in the amorphous region during uniaxial stretching were probed via the use of TASN, which allowed a direct visualization of the necking initiation and propagation processes as well as a quantification via electron paramagnetic resonance spectroscopy.
为了可视化并同时量化结晶聚合物薄膜在单轴拉伸过程中的细颈化行为，将四芳基琥珀腈（TASN）部分引入到聚合物主链的中心位置。TASN能够产生一种相对稳定的自由基，该自由基在受到机械应力时会发出黄色荧光。在以TASN为中心的结晶聚合物的单轴拉伸试验中，源自解离的TASN自由基的黄色荧光被用于微观观察，以显示聚合物链在拉伸方向上的取向。此外，通过比较线性和星形TASN中心结晶聚合物在拉伸变形过程中的自由基生成情况，我们发现星形聚合物中的TASN解离率更高，因为星形聚合物有更多的链连接到片晶上。因此，通过使用TASN探究了单轴拉伸过程中非晶区产生的微力，这使得能够直接可视化细颈化的起始和传播过程，并通过电子顺磁共振光谱进行量化。
