Synthesis And Assembly Of Sub-1 Nm Nanowires And Applications Of Their Properties

Size effect has always been the core issue in the research of nanomaterials,and when the size of nanomaterials reduced to less than ten nanometers,or even sub-nanometer level,their properties can often undergo qualitative changes.In the research of nanomaterials,the core aim is the qualitative leaps of the properties brought by the size decrease.The size effect of one-dimensional nanomaterials mainly depends on the reduction of their radial size.Reducing the radial size to a certain extent may lead to great changes in their structure,conformation or even properties.One-dimentional sub-1 nm nanomaterials are similar to linear macromolecules,which can show abundant conformations.Like organic macromolecule system,they can form three-dimensional network structure in solvents and gels can be obtained.In addition,they can assemble like biomacromolecule assembly.By adjusting their conformation and three-dimensional bulk materials can be obtained.This dissertation focused on the sub-1 nm nanowires.Transparent and highly flexible nanowire fibers were prepared by wet spinning of Gd OOH sub-1 nm nanowires.By characterizing the internal structure of the fibers and the structural changes during tensile fracture,it was proved that the high flexibility of the fibers mainly came from the ordered arrangement of spring-like sub-1 nm nanowires,which were like some small springs.The nanowire fibers could undergo elastic deformation to a certain extent and large plastic deformation in the stretching process,which hadn't been reported before in the field of nanowire fibers,laying a foundation for the preparation of highly flexible nanowire materials like the polymer.Sub-1 nm nanowire films were prepared and their optical properties and functions were studied.Gd OOH sub-1 nm nanowires were fabricated into transparent and flexible films by wet-spinning method.Because the sub-1 nm nanowires in the films were arranged regularly along their long axis,the films were strongly anisotropic,exhibiting obvious birefringence.Incident light would be scattered anisotropically through the nanowire films.By introducing fluorescent quantum dots or quantum rods into the films,they could show polarized fluorescence,providing a new idea for the application of nanowires in the wave plate and quantum dots-liquid crystal display.Furthermore,we found that Gd OOH sub-1 nm nanowires can self-assemble with 100%efficiency and formed the macroscopic helical assemblies,and we also tried to introduce non-chiral fluorescent organic dyes into the assembly.Combining with the results of molecular dynamic simulation,the formation mechanism and chiral evolution of macroscopic helical assemblies were elucidated,which were expected to be applied to the construction of novel chiral structures.In addition to the various properties and functions based on the intrinsic anisotropy of sub-1 nm nanowires,we also tried to enrich their functions by adjusting the components of sub-1 nm nanowires.We synthesized tungsten bronze nanowires and investigate their assembled structures and photothermal performance.Phosphomolybdic acid cluster-bismuth hydroxide composite sub-1 nm nanowires were prepared.Photothermal films were prepared with the nanowires and applied in the seawater desalination.It provided ideas for the preparation of sub-1 nm nanowires devices with diverse components and rich functions.