Study On The Synthesis And Self - Assembly Properties Of Rigid Bar - Linear Molecules With Different Rigid Bar

The construction of supramolecular architectures with well-defined shapes and sizes which have potential for fundamental and practical implications in areas such as nanoscience, supramolecular chemistry, advanced materials science, catalyst science, and Biomimetic chemistry. Liquid crystalline assemblies of Coil-Rod-coil tri-block oligomers consisting of rigid rod segment and flexible coils provide various liquid crystalline supramolecular structures by microphase separation interaction、H-bond interaction、πn-π s tacking interaction and so on. This thesis designed and synthesized linear shaped, V-shaped and T-shaped rigid-flexible tri-block liquid oligomers, The compound structures were characterized with 1H-NMR and MALDI-TOF mass spectroscopy. The self-assembling behavior of the compounds is investigated by means of differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), optical polarized micrograph (POM) in the bulk state and liquid crystal state. Meanwhile, the self-assembling behavior of the target molecule is investigated by UV-vis, fluorescence spectra and dynamic light scattering in the aqueous solution. Mainly discuss the influence of rigid shape、flexible chain length、flexible clain block volume fraction on the self-assembly behaviors.For linear shaped rigid-flexible tri-block liquid oligomers with biphenyl connected by ether and ester linkage, we have investigated the influence on the self-assembly structures by altering length of the alkyl chains at the end of the rod, length of the alkoxyl chains,alkoxyl chain volume fraction and so on. The experimental results reveal that molecule with low Poly (propylene oxide chain) self organize into a tetragonal perforated lamellar (TPL) and bicontinuous cubic (BCC) structures in the solid state and the liquid crystalline phase, respectively. In addition, molecules containing longer coil chains self assemble into the columnar nano-structures in the solid state and liquid crystalline phase. When transform coil chains cross section area for smaller Polyethylene oxide chain at the end of rod all self organize into columnar nano-structures. By controlling the different flexible chain to influence π-π stacking interactions between the molecules can build the strength of diverse supramolecular nanostructures.We investigated the self-assembling behavior for the rigid part of the T-shaped and V-shaped molecules in the bulk and in the aqueous solution. V-shape molecules from one side connected to polyethylene oxide chain and the other end connected to alkyl chain self assemble into oblique columnar structure in the bulk state. The UV-visible spectra measured data display blue shift and fluorescence intensity was quenched, it indicted that molecules aggregation in aqueous solution, forming radius of 71nm nano-aggregates from the Dynamic Light Scattering test, AFM tests show that self-assemble into fibers. We also studied the aggregation behavior of T-shape in aqueous solution, the results reveal that it aggregate into miscelles with radius of 110nm.