Fabrication Of Hydrophobic Materials Via Chemical Vapor Deposition And The Research Of Their Properties And Applications

The wetting behavior of solid surfaces by a liquid is an important aspect of surface chemistry.The wettability of surface is governed by both the chemical composition and the geometrical microstructure of the surface.Many novel hydrophobic materials have been fabricated via various physicochemical methods.However,their applications still face great challenges,which are greatly limited by the complicated fabrication methods,high cost or excessive raw materials.In this thesis,a simple,green,and high efficient chemical vapor deposition?CVD?method was used to fabricate novel functionalized hydrophobic materials,and their properties and applications were explored specifically.The major creations of this thesis were as follows:?1?Hydrophobic sand core funnels?SCs?were first fabricated via the vacuum-assisted CVD?VCVD?,and their physicochemical properties and applications were investigated.The surface wettability mechanism of SCs was explored specifically.?2?The VCVD method was applied to the hydrophobic modification of cellulosic materials and proved the universality of the method.The physicochemical properties and applications of hydrophobic filter papers?FP?were studied extensively.?3?Silane-modified cellulose nanocrystals?CNC?were prepared by VCVD method and their applications in structuring edible oils were evaluated.The main contents and conclusions of this thesis include the following parts:A simple,green and facile VCVD method was adopted to fabricate hydrophobic surface on SCs via reacting with the perfluorooctyltriethoxysilane?PFTS?vapor.The WCAs of the PFTS-modified SCs increased from 120 to 149°with increasing the surface roughness of the material itself,as well as increasing the reaction temperature and time.The surface wettability of the modified SCs is adapted for Cassie model with partial wetting.The developed SCs preserved novel physicochemical properties including the outstanding chemical stability,good mechanical properties in extremely acidic/alkali solutions,underoil surperhydrophobicity and remarkable self-cleaning behavior.G2-4.0h exhibited an excellent oil/water separation efficiency highly to 99%,and a permeation flux of 11000 L m^-2 h^-1 for ethyl ether under solely gravity.For G3-4.0h,the maximum permeation flux could reach to 20000 L m^-2 h^-1 for ethyl ether under the vacuum degree of 3.8 kPa.Moreover,G4-4.0h^G6-4.0h with small pore sizes have been successfully applied in water-in-oil emulsion separation.The results show that the hydrophobic modified SCs can be used in various fields.Hydrophobic cellulosic materials with any shape and size were successfully prepared via the VCVD method.The surface modification of FP with PFTS was investigated in depth.The results indicated that PFTS overlapped densely on the surface of the cellulose matrix,and the silane content and water contact angle were45–55 mg g^-1 and 146±3°,respectively,under the optimal conditions.The mechanical properties in the wet state and the thermal stability of the PFTS modified FP were significantly improved compared with the FP.PFTS modified FP retained good chemical stability in harsh conditions of acidic,alkaline and saline solutions.It was successfully applied in separating a series of oil/water mixtures with a separation efficiency of over 99%.Moreover,the CVD method was applied for a continuous hydrophobic modification of viscose rayon,which is suitable for the large-scale production of hydrophobic cellulosic materials.Amino modified cellulose nanocrystals?ACNC?were prepared to enhance their thermal stability.The silanization of ACNC?n-DDTS-ACNC?was developed via the simple VCVD method.The results proved that the n-dodecyltrimethoxysilane?n-DDTS?was successfully introduced onto the surface of ACNC.n-DDTS-ACNC displayed a good hydrophobic/lipophilic property,and can be well dispersed in edible oils such as sunflower-seed oil and peanut oil.n-DDTS-ACNC showed remarkable thickening effect for edible oils.With a high content of n-DDTS-ACNC,a solidified oleogel could be formed.The viscosity of the oily suspension exhibited temperature dependence and shear-thinning behavior.Furthermore,the liquid crystal phase was observed with the increase of n-DDTS-ACNC contents.In this thesis,we provide a simple,green,and high efficient VCVD method to fabricate novel hydrophobic materials.The method is proved to be suitable for various materials ranging from inorganic to polymer materials.The structure and properties of the hydrophobic materials were investigated,and the relationship of surface structure and wettability was explored.These materials could be used in oil/water separation,self-cleaning,oil structuring and so on.Therefore,this thesis exhibited both scientific significance and practical applications.