Author: Ni Bo

Publisher:

Published: 2018

Total Pages: 139

ISBN-13:

The giant molecules systems exhibit very interesting behaviors in the supramolecular assemblies over the past several years compared to other macromolecular systems. As an old Chinese saying goes "good tools are prerequisites for a successful execution of a job". This dissertation focuses on the synthetic possibilities based on the previous work and try to explore some progress in the first part. The second part of the dissertation encapsulates the self-assembly behaviors of the synthesized giant molecular systems. A pre-functionalization method was developed to achieve giant molecular families with more abundant functionalities. Fluorinated polyhedral oligomeric silsesquioxane (FPOSS), long alkyl chain functionalized POSS (C8POSS), and protected carboxylic acid group functionalized POSS (tAPOSS) were designed and prepared. These kinds of molecules are viewed as molecular nanoparticles (MNPs). The reactivities of the modules was proved by combining them with polymer systems like polystyrene via "click" chemistry. These precisely defined functionalized POSS-containing hybrids could serve as model molecules to investigate the self-assembly behaviors of giant molecules.The solution self-assembly of a giant surfactant consisting of a polystyrene-block-poly (ethylene oxide) (PS-b-PEO) diblock copolymer tail tethered onto a fluorinated polyhedral oligomeric silsesquioxane (FPOSS) cage in 1,4-dioxane/water was investigated. Abundant unconventional micellar structures including toroids, two-dimensional hexagonally patterned colloidal nanosheets, and laterally structured vesicles were observed.2 This study not only exhibits various unique morphologies, but also promotes the fundamental understanding on the pathways of the transformations between different morphologies in the solution self-assembly behavior of giant surfactants.In the MNPs and polymer hybrid systems, the MNPs were with precise molecular weights and chemical compositions. But the polymers used still have a molecular weight distribution which originates from the nature of the polymerization methods applied. To eliminate the polydispersity effect from the system, it is crucial to have molecular systems with precise molecular weights and chemical structures from the physical point of view. Upon this anticipation, we have designed a series of dendrons which are compositionally identical, but their linkers are in different chemical connection geometries. These sets of macromolecules are composed of hydroxyl group functionalized POSS (DPOSS) and isobutyl functionalized POSS (BPOSS). The final dendron structure consists of three parts, one DPOSS at the apex, four BPOSSs at the periphery and the flexible linkers. Note that this series of dendrons is topological isomers. Self-assembled structures of four dendron topological isomers were studied using SAXS and TEM. The results help us to understand the role of linkers in a amphiphiles system and give us some guidance on how to design a molecular system in the future.