The Influence Of Side Chains On Self-assembled Structures Of Liquid Crystal Oligomer Based On The Polyethylene Oxide Chain

The development of novel supramolecular materials with nanometer-scale architectures and these architectures'properties are currently of great interest in molecular design. Liquid crystalline assemblies of Rod-coil tri-block oligomers containing rigid rod segment and flexible coils(rod-coil molecules)provide a rich variety of different liquid crystalline structures with nanoscale dimensions. This thesis mainly discusses the self-assembly behaviors at solid state, liquid crystalline state and in solution of T-shaped, H-shaped and linear shaped rod building block oligomers, as well as the influence of side chain of molecular on the self-assembly behaviors of such tri-block oligomers.T-shaped coil-rod-coil tri-block oligomers, consisting of a dibenzo[a,c]-phenazine unit were synthesized and the self-assembling behavior of these molecules was investigated in the crystalline phase. We summarize the influence on the self-assembly structures of the T-shaped rod-coil oligomers by changing length of the alkoxyl chains at the end of the rod; the length of alkyl chains in the center of the rod; introduction of lateral methyl groups attached to the surface of rod and coil segments. The experimental results reveal that the length of the flexible PEO coil chain influence construction of various supra-nanostructures from lamellar structure to rectangular columnar structure. It is also shown that introduction of different length of alkyl side chain groups in the backbone of the T-shaped molecules affect the self-organization behavior to form hexagonal perforate layer or oblique columnar structures. In addition, lateral methyl groups attached to the surface of rod and coil segments, dramatically influence the self-assembling behavior in the crystalline phase. T-shaped molecules containing a lateral methyl group at the surface of rod and PEO coil segments, self-assemble into3D body-centered tetragonal structures in the crystalline phase, while molecules without a lateral methyl group based on PEO coil chain self-organize into2D oblique columnar crystalline structures.A class of ?-conjugated, skewed H-shaped oligomers was synthesized and the self-assembling behavior of these molecules was investigated in the crystalline phase. The results indicates that that the length of the flexible PEO coil chain influence construction of various supra-nanostructures from lamellar structure to oblique columnar structure. H-shaped molecule containing a lateral methyl group at the surface of rod and PEO coil segments, self-assembles into3-D body-centered tetragonal nanostructures in the crystalline phase, while molecules without a lateral methyl group based on PEO coil chain self-organize into1-D lamellar structure or2-D columnar nanostructures.Four categories of linear-typed molecules with lateral methyl groups in the surface of rod and coil segments self-assemble into3-D assemblies in the liquid crystalline mesophase, depending on the the length of poly(ethylene oxide) coil or lateral chain in the center of the rod. The experimental results reveal that the molecules containing a lateral methyl group at the surface of rod and PEO coil segments, self-assembles into3-D hexagonal close-packed structure or3-D body-centered tetragonal micelle or3-D bicontinuous cubic nanostructure in the liquid-crystalline phase, while molecules without a lateral methyl group based on PEO coil chain self-organize into1-D lamellar structure or2-D columnar nanostructures.