Preparation Of Hydrophobic Diazo Compounds And Its Application In Surface Modification Of Materials

The demand for high quality and versatile functionality of the materials used in industrial production and everyday life increases continually with the develppment of science and technology,and the living stadard of people.Researchers have labored for decades to develop high-quality functional polymer materials to fulfill the ever-changing need of human society.More importantly,the discharge of oily domestic industrial wastewater and the oil spills caused by the rapid development of the ocean industry have become a serious threat to the ecological environment,marine species and human health.Scientists have made their efforts to develop more effective,selective,cost-efficient,and environmentally friendly materials and methods for separating oil-water mixtures.In this thesis,we successfully introduced the synthesized hydrophobic diazo compounds to the surface of the substrate materials by the strategy of carbene insertion post-modification under mild conditions(heating,or UV irradiation).The functional groups(phosphate ester,perfluorinated alkane)were introduced indirectly by permanent covalent bonding.The low surface energy characteristics of these functional groups were used to construct unwettable materials with qualities opposite to the corresponding original materials.A range of characterisation methods,including SEM,XPS,TGA,contact angle test,mercury pressure test,and tensile test,were used to examine the wettability,mechanical behavior,chemical stability,and microstructure of these materials before and after modification.The separation application of modified wood aerogel,filter paper,and cotton cloth was evaluated by separating oil-water mixtures and emulsions with diverse characteristics(filtration and absorption).The following are the detailed studies:1.Suitable functional groups with different wetting properties(hydrophobic phosphonates,perfluorinated alkanes)were selected to prepare aryl diazo compounds containing different hydrophobic functional groups.i: Using trifluoroacetic anhydride(TFAA)as protective reagent of amine,4-phenoxyaniline was transformed to aromatic ketones by the Friedel-Crafts acylation reaction with perfluorooctane(1-I-1H,1H,2H,2H-perfluorohexane/octane/decane).These ketones were exchanged to hydrazones using hydrazine monohydrate,and the target products,perfluorinated alkyl aryl diazo compounds,were synthesized by the subsequent manganese dioxide oxidation.ii: Friedel-Crafts acylation was used to create the basic skeleton of aryl diazomethanes from toluene and isophthaloyl dichloride.The phosphonate group was then introduced through the bromine radical substitution reaction and the well-known Arbuzov reaction,which was treated with hydrazine monohydrate to obtain corresponding hydrazine.These hydrazone was finally diazotized in the presence of potassium hydroxide and manganese dioxide to get the target phosphonate aryl diazomethanes.2.The above-mentioned aryl diazo compounds were changed to carbenes quickly via light or heat,and then undergo carbene-insertion process of X-H bonds(X = C,N,O,)to create permanent covalent bonding with the substrate materials.X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),and water contact angle testing were used to measure the surface chemical composition and wettability of the modified materials.The results demonstrate that the surface elements and the wettability of the modified materialsaltered dramatically,indicating that the functional groups were successfully linked onto the material surfaces.In addition,the thermal stability,porosity,and tensile strength of the substrates were examined before and after modification,which was discovered that the intrinsic properties of modified materials were not weakened.This strategy developed new thought for the research field of surface wettability.3.The carbene-modified materials showed outstanding self-cleaning,oil-water mixture separation,and emulsion separation capabilities.The 3D wood aerogel modified by perfluorinated alkyl diazo compounds has a water contact angle of 153°,and its oilwater separation efficiency reached to 95%,and showed no significant reduction of separation flux after 20 cycles.The filter paper modified with perfluorinated alkyl diazo compounds could separate a variety of water-in-oil emulsions.This opens up application possibilities for wettability-controlled coatings and oil-water separation materials.In summary,the hydrophobic aryl diazo compounds can be used to modify a broad range of substrate materials to change their wettability.Furthermore,surface chemical modification based on the carbene insertion process can not only vary the surface properties of polymeric materials without changing the intrinsic qualities,but also shows adaptablity for a variety of substrate materials.Moerover,these materials after surface modification exhibit good separation capabilities and potential application in the oil-water separation field.