School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
ACS Macro Lett. 2022 Sep 20;11(9):1060-1066. doi: 10.1021/acsmacrolett.2c00271. Epub 2022 Aug 17.
We report the effect of alkyl side chain branching on melt-recrystallization of nanoconfined polypeptoid films using poly(-octyl glycine) (PNOG) and poly(-2-ethyl-1-hexyl glycine) (PNEHG) as model systems. Upon cooling from the isotropic melt, confined PNOG molecules recrystallize into a near-perfect orthorhombic crystal structure with the board-like molecules stacked face-to-face in the substrate-parallel direction, resulting in long-range ordered wormlike lamellae that occupy the entire film. By contrast, rod-like PNEHG molecules bearing branched -2-ethyl-1-hexyl side chains stack into a columnar hexagonal mesophase with their backbones oriented parallel to the substrates, forming micron-sized sheaf-like superstructures under confinement, exposing large areas of empty spaces in the film. These findings highlight the effect of alkyl side chain branching on the packing motif and multiscale crystalline structure of polypeptoids under a nanoconfined geometry.
我们报告了支链烷基对纳米受限聚肽类薄膜的熔融重结晶的影响，使用聚（辛基甘氨酸）（PNOG）和聚（2-乙基-1-己基甘氨酸）（PNEHG）作为模型体系。在从各向同性熔体冷却时，受限的 PNOG 分子重结晶成近乎完美的正交晶体结构，板状分子在基板平行方向上面对面堆叠，形成占据整个薄膜的长程有序的蠕虫状层。相比之下，带有支链 -2-乙基-1-己基侧链的棒状 PNEHG 分子堆积成柱状六方中间相，其骨架与基板平行，在受限条件下形成微米级的束状超结构，在薄膜中暴露大量的空旷空间。这些发现强调了支链烷基对纳米受限几何形状下聚肽类的堆积模式和多尺度晶体结构的影响。
