Synthesis And Characterization Of Polyhedral Oligomeric Silsesquiozane Based Giant Molecular Shape Amphiphiles

Author : Su Zebin
Publisher :
ISBN 13 :
Total Pages : 194 pages
Book Rating : 4.:/5 (126 download)

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Download or read book Design, Synthesis, and Self-assembly of Giant Shape Amphiphiles with Precisely Controlled Compositions, Interactions, and Geometries Via a Molecular Lego Approach written by Su Zebin and published by . This book was released on 2019 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Self-assemblies of soft matters attract broad interests of material scientists since this technology provides versatile designs, relatively low economic cost, convenient route to construct ordered structures at different scales. Tremendous achievements such as various of hierarchical architectures and diverse attracting properties have been achieved by utilizing by self-assemblies of polymer building blocks. However, the challenges of precise controls of designed chemical primary structures, compositions, molecular topology and exact constructions of assembled structures in synthetic polymers are far away from being well addressed. In this dissertation, a novel approach named "molecular Lego approach" has been utilized to construct various well-defined giant molecules, constructed by several types of building blocks, which are nano-sized molecules with precise molecular structure, relatively rigid conformation, and defined molecular symmetry. Three categories of "giant shape amphiphiles" with different driving force for self-assemblies were designed, synthesized, and investigate in detail. First, we designed and synthesized a series of nanosized giant shape amphiphiles in which a triphenylene core is attached to six identical polyhedral oligomeric silsesquioxane (POSS) cages at the periphery through covalent linkers with tunable lengths. Giant shape amphiphiles are molecular building blocks that consist of different moieties of distinct shapes, and engage in competing interactions. The relatively weak [pi-pi] stacking interactions among conjugated aromatic triphenylene cores enable the segregation from peripheric BPOSS cages (POSS functionalized with seven isobutyl groups). Moreover, the tunability of the linker length enables the formation of various ordered spherical phases. Using this platform, we report the experimental observation of the FK Z phase in a soft matter system. Based on these results, we then designed and studied the self-assembly phase transition behaviors of another two series of giant shape amphiphiles. The driving force of these two series of giant shape amphiphiles are only [pi-pi] stacking interactions supplied by triphenylene core, but also hydrogen bonding supplied by the linkers. With systematically tuning the length and rigidity of the linkers, we observed various of phases, including DDQC phase, F-K [sigma] phase, body centered cubic (BCC) phase and HEX phase. Furthermore, we find two sets of giant shape amphiphiles based on benzene-1,3,5-tricarboxamide and cyclotriphosphazene. There is not [pi-pi] stacking interaction between these two types of cores. The driving force for these two sets of samples are mainly hydrogen bonding. These two sets of giant shape amphiphiles self-assemble into BCC phase and A15 phase. These results suggest that the crown shape molecular design is a general way to construct complex spherical phases. These studies suggest that "molecular Lego approach" self-assemblies based on well-defined giant shape amphiphiles can be a powerful platform for achieving unconventional hierarchical structures and pave a new way for supramolecular self-assembly with expected structure, designed properties and function.