Synthesis Of Fluorinated Superamphiphobic Polyurethane Nanofibers

Fluorinated polyurethane (FPU) is a species of novel macromolecule functional materials. Due to the introduction of fluorinated groups, FPU has very low surface energy, excellent resistance to chemicals, water and oils, and has broad promissing applications in leather, fabric finishing. But in China, fluorinated leather, fabric finishing agents mainly rely on importation from abroad. Moreover, limited by the fluorine-containing raw materials fluoropolymers are very expensive. Therefore, it is of great significance to independently develop innovative, low-cost, high-finishing performance fluorinated poryurethane finishing agents.Electrospinning technology is one of the easiest way to regulate the size and morphology of fiber. Electrospun fibers have high specific surface area and porosity, and have a wide application potential in the field of information technology, energy, environmental, biomedical, and national security.In this thesis, we first described the synthesis methods of fluorinated polyurethane and its applications, then we talked about electrospining technology, and the applications of electro-spun nanofibers. This thesis started from the synthesis of fluorinated polyurethane, and the characterization of its structure via FT-IR and NMR. We discussed the impacts of water repellent and oil repellent properties of the fluorinated polyurethane as a leather, textile finishing agents by investigating the feeding methods of the materials, the feed ratio and the length of the fluoroalkyl chain means, which can return the synthetic parameters though contact angle, water or oil-repellent level. Therefore, we can obtain the best finishing performance fluorinated polyurethane. And its thermal properties and crystalline properties were characterized by means of DSC, TGA, XRD etc, respectively.Another important aspect of the thesis is using electrospinning technique to prepare fluorinated polyurethane nanofibers. FE-SEM was used as the main analytical tools to analyze the influence of solution concentration on the surface morphology, contact angle and surface adhesion of fluorinated polyurethane nanofibers. It is shown that the FPU nano-fiber membrane prepared by 18wt%of the solution has the most excellent hydrophobic properties under certain spinning conditions, however, the surface adhesion phenomenon of this film is serious. By adding SiO2nanoparticles to the solution, we could obtain a micro-nano multi-level structured nanofiber membrane with its surface adhesion phenomena disappearing. It is also revealed that when the SiO2particle concentration was1wt%, the contact angle of water and oil are165°and151°, respectively, and the roll angle is only2°, which means it has excellent superamphiphobic and self-cleaning properties. Moreover, the FPU-18/SNP-1membrane has the highest roughness, which is confirmed by optical profilometer. In addition, a large number of porous structures in the fiber membrane were observed by BET analysis. Fractal dimensional analysis indicated that the FPU-18/SNP membranes exhibited surface fractal features with irregular rough structure, and there is a positive correlation between the hierarchical roughness and amphiphobicity. Significantly, the designed test shows that the as-prepared membranes could load1.5kg water or oil, and maintained an extremely high air permeability of2L/min at the same time.