New progress in polymer assembly! "JACS", academician Cheng zhengdi, reported that a variety of semiconductor nano lattice was assembled with a simple ball and stick

The assembly structure of materials has an important influence on the properties of materials In recent years, the study of the influence of the shape of the assembly on the assembly structure is a hot topic in the field of self-assembly As the two most basic shapes in nature, ball and rod have been widely studied But what happens if the two basic shapes of the ball and the stick are connected by chemical bonds? Although this is a seemingly simple problem, it is not easy to solve Recently, Cheng zhengdi, a Chinese scientist at the University of Akron, used C60 (ball) and oligofluorene of (stick) as basic units to study the assembly behavior of c60-of in solid phase in detail, thus obtaining a variety of semiconductor nano lattice Figure 1: chemical structure diagram of c60-of complex source: J am Chem SOC In the basic structure of the complex studied, there is a hydrophilic C60 molecule and one or two of molecules, which are connected with each other through chemical bonds Among them, of molecules can be connected with C60 at the end or in the middle, forming four kinds of isomers with different topological structures (a total of 24 molecules) Another reason for choosing C60 and of as basic units is that they are excellent organic semiconductor materials It is worth noting that all complexes have a single molecular weight distribution However, it is not easy to synthesize such a compound molecule Although the researchers in the text only downplay its synthesis, its synthesis process is very challenging Fig 2 TEM and SAXS characterize the source of assembly structure of four isomers: J am Chem SOC Research shows that the assembly behavior of the complex is completely dominated by its molecular shape and topological structure, which is completely different from the traditional polymer assembly behavior L-type and T-type molecules have identical chemical structures, but their assembly structures are quite different Taking a C60 and two of complexes as examples, with the increase of the rod length of of of, the assembly structure of T-type molecules changes from lamellar phase to columnar phase, Frank Kasper A15 phase, and finally to the spherical phase of BCC; however, L-type molecules, as isomers, keep the lamellar phase all the time, and even have rare highly asymmetric lamellar phase Figure 3 Phase diagram source of assembly structure of all complexes: as a master of polymer physics, academician Cheng zhengdi's team is indispensable to systematically characterize and deeply analyze the assembly structure of all 24 complexes in this study, and focuses on how molecular shape and topological structure affect the final assembly structure Considering that both C60 and of are organic semiconductor materials, these highly ordered assemblies are also called semiconductor lattice So do these different lattice really have different electrical properties? In the end, the electrical properties of these assemblies are characterized in detail by TRMC Simply speaking, different lattice structures do have different conductivity The conductivity of layered and columnar phases is higher than other structures, because of has better orientation in the layered and columnar phases Figure 4 source of influence of assembly structure on electrical properties: J Am Chem Soc in general, as the basic research of polymer assembly, this JACS is novel and excellent enough to organically combine polymer synthesis and polymer physics It not only provides a new idea for the design and assembly of new polymers, but also provides an important reference for the preparation of efficient organic semiconductor solar cells and devices Paper link: http://pubs.acs.org/doi/10.1021/jacs.7b10193 brief introduction of academician Cheng zhengdi: http://www2.scut.edu.cn/aismst/2017/0621/c14517a169404/page.htm academician Cheng zhengdi