Self-Assembly Of V-shaped Amphiphilic Oligomers:Influence Of Lateral Groups At The Rigid Center On Self-asssembling Behavior

Rod-coil molecules 1-4 consisting of V-shaped rod segment and oligo(ethylene glycol)(OEG)as the coil segment,were synthesized and characterized.At the apex of their bent-shaped rigid building blocks,molecules la-lb incorporate a butoxy group,molecules 3a-3b incorporate an ester group,molecules 4a-4b incorporate a carboxyl group.While both lb-2b and 3b-4b contain a lateral methyl group between the rod and coil segments.The self-assembling behavior of these molecules was investigated using DSC,SAXS,CD,AFM,and TEM in bulk and aqueous solutions.In this thesis,we mainly discussed the influential factors of intermolecular interaction:vertex substituents and lateral methyl group.In the bulk state,la self-assembles into oblique columnar structures,whereas 1b,incorporating butoxy and lateral methyl groups,self-assembles into three-dimensional body-centered tetragonal structures.Molecules 2a and 2b with no vertex groups,and 2b incorporating a lateral methyl group,self-assemble into hexagonal perforated lamellar and oblique columnar structures,respectively.Molecule 3a incorporate ester group,self-assembles into oblique columnar structures.Meanswhile,4a-4b incorporate carboxyl,self-assemble into hexagonal perforated lamellar and oblique columnar structures.In dilute aqueous solutions,la assembles into tubular nanoassemblies,while 1b self-organizes into micelles and nanoparticles.Molecules 2a-2b spontaneously aggregate into nanoribbons and helical nanofibers,which implying that the lateral methyl group induces the helical stacking of the rod building block.3a-3b spontaneously aggregate into nanofibers and nanorings,4a-4b self-organizes into nanosheets and vesicles.When vertex substituent are butoxyl or ester groups,the steric effect weakens intermolecular forces,which lead to a 2-D and 3-D nanostructures.In other hand,molecules without vertex substituent self-assemble into 1-D or 2-D structures.As the vertex is carboxyl,we estimate that intermolecular hydrogen bonding enhances the intermolecular forces to form 1-D or 2-D structures.These results reveal that the vertex group and lateral methyl groups between the rod and coil segments dramatically influence the creation of supramolecular nanostructures and morphologies.