SUSTech He Feng's research group has made important research progress in the field of controllable preparation of two-dimensional micro/nano materials
The two-dimensional planar structure of micro-nano materials has great application prospects in the fields of biomedicine, chemical sensors, electronic information and smart materials due to its nano-size effect, larger specific surface area and better planar structure. The application properties of two-dimensional micro-nano materials are closely related to their aggregated structure, shape and size. Therefore, studying how to prepare two-dimensional micro-nano materials with regular shapes and controllable sizes has significant theoretical and practical significance. At present, the controllable preparation of micro-nano materials with two-dimensional planar structures is still facing great difficulties. In particular, it is a great challenge to prepare micro-nano materials with multi-level, multi-level structure and two-dimensional planar structure with controllable size and morphology, and richer structures and functions.
Recently, the research team of Associate Professor Feng He from Southern University of Science and Technology used the amphiphilic π-conjugated block polymer (polyhexylthiophene-b-polyethylene glycol monomethyl ether, P3HT-b-PEO) as the research object, using solution self-assembly The method produced a two-dimensional micro-nano material with a rectangular structure with a regular morphology and a controllable size. In isopropanol solution, by heating and dissolving, then cooling and aging, P3HT-b-PEO self-assembled to form a two-dimensional micro-nano material with a rectangular structure. By controlling the segment length of P3HT and PEO, the size and aspect ratio of the rectangular two-dimensional micro-nano materials can be adjusted, as shown in Figures 1 and 2.
Figure 1. The morphology of the assembly formed by P3HT-b-PEO in isopropanol solution (PEO remains unchanged, while the segment length of P3HT increases sequentially).
Figure 2. The morphology of the assembly formed by P3HT-b-PEO in isopropanol solution (P3HT remains unchanged, and the segment length of PEO increases sequentially).
In addition, by controlling the concentration of the polymer, the size of the two-dimensional rectangular micro-nano material can be adjusted; when the polymer concentration exceeds a certain value, the block polymer can be assembled to form a more complex multi-layered two-dimensional nano material, as shown in the figure 3 shown.
Figure 3. The morphology of the assembly formed by P3HT-b-PEO in isopropanol solutions of different concentrations (the concentration increases sequentially).
Through in-depth research on the formation process and microstructure of two-dimensional rectangular nanomaterials, it is found that in isopropanol solution, the block polymer P3HT-b-PEO first self-assembles to form one-dimensional nanofibers, and then one-dimensional nanofibers again Self-assembly forms a two-dimensional rectangular nanomaterial, as shown in Figure 4. This paper demonstrates the formation process of two-dimensional rectangular micro-nano materials, as shown in Figure 5.
Figure 4. The morphology of the assembly formed by P3HT-b-PEO in isopropanol solution (during the cooling process).
Figure 5. Schematic diagram of the formation process of two-dimensional rectangular micro-nano materials.
This study reported for the first time that a P3HT-based block polymer produced a two-dimensional micro-nano material with a regular morphology and a controllable size, and directly confirmed that the formed two-dimensional rectangular nano-material was assembled by block polymers through multiple stages. The formation; provides new ideas for the controllable preparation of two-dimensional micro-nano materials (especially two-dimensional micro-nano materials with multi-layer structure), and has a good application prospect in the field of organic optoelectronic materials.
The paper was published in Macromolecules, entitled "Rectangular Platelet Micelles with Controlled Aspect Ratio by Hierarchical Self-assembly of Poly(3-hexylthiophene)-b-Polyethylene Glycol". Qi Rui, a postdoctoral fellow from Southern University of Science and Technology, is the first author of the paper, Associate Professor Feng He from the Department of Chemistry of Southern University of Science and Technology is the only corresponding author, and Southern University of Science and Technology is the only correspondent. In addition, Zhu Yulin, a direct Ph.D student of the 2018 SUSTech-Harbin Institute of Technology, Han Liang, research assistant professor at the Grubbs Institute of Southern University of Science and Technology, and Wang Meijing, research assistant in the Department of Chemistry, Southern University of Science and Technology, also made important contributions to the paper.
This research was supported by the National Natural Science Foundation of China, the Shenzhen Basic Research Program, the Shenzhen Nobel Prize Scientist Laboratory, the Guangdong Innovation and Entrepreneurship Team Project, and the Southern University of Science and Technology Analysis and Testing Center.
In addition, Feng He's group has also published a series of related work on one-dimensional, two-dimensional and multi-stage self-assembly based on π-conjugated block polymers in Nature Communications, Small Methods, Macromolecules, Polymer Chemistry, CCS Chemistry in recent years.