Study On Synthesis And Thermal-responsive Self-Assembly Of Rod-Coil Molecules

Design and synthesis of novel supramolecular nanomaterials with properties of stimulus response is widely drawing people’s attention, which is important for the preparation of new type of intelligent functional materials. Thermal response of nano-materials as a kind of important component of those has been widely studied. The supramolecular structures of rod-coil molecules in bulk state and in aqueous solution showed good response to temperature changes, which can assemble into different kinds of novel supramolecular structures.In this paper, rod-coil molecules la, lb and 1c, of which the X-shaped rod consists three branches, were synthesized. The flexible part of 1 a and 1 b are hydrophobic alkyl chains, and the flexible part of 1c, liquid at room temperature, is hydrophilic polyethylene oxide chains. In the bulk state, 1a and 1b exist in disorderly state of micelle. In the aqueous solution, lc gathered themselves together and formed into spheric micelles and helical nanofibers. Fork molecular 2a,2b and 2c have branches on both ends of the rods and polyethylene oxide flexible chains with the degree of polymerization of 4,7,12, respectively. Molecule 3a,3b are solid at room temperature, but 2c is liquid. In the bulk state, solid structure of molecule 3a is inclined column, while the solid phase structure of the 2b is simple monoclinic phase. In the aqueous solution,2a,2b,2c all gathered, the aggregate particle size decreases with flexible chain growth. The self-assembly properties of the two series of molecules showed that the branching rigid rod structure is a big obstacle in their ability to form a stable supramolecular structure.Molecule 3a,3b,3c contain ester bond in the rod part, chiral center in flexible chain and methyl incorporated in the rod-coil interface. In the bulk state, the solid phase structure and liquid crystal phase structure of 3a,3b are of double layer structure, while the solid phase and liquid crystal phase structure of molecule 3c is hexagonal column, when cooling to the solid phase molecule 3 c presented a layered structure. Molecule 3a,3b,3c generally gathered into 3d layer structure showed that the dipole-dipole interaction of ester base is stronger than that of the incorporation of methyl into the interface of rod-coil interface and played a leading role.