Preparation Of Bis-perfluoroalkylated Derivatives And Its Application On Surface Treatment

Polymer with long-chain perfluoroalkyl groups(?8)at the side-chain is well-known as one of the most desirable polymeric materials,which can provide extremely low surface energy.However,the degradation of long-chain perfluoroalkyl releases biopersistent perfluorooctanoic acid(PFOA)or perfluorooctane sulfonylate(PFOS),which is difficult to degrade furtherly in the natural environment.These degradating products possess bioaccumulation and long-distance migration,which are harmful to human health and our living environment.Fortunately,it was found that perfluorinated chains of six carbon atoms or less do not bioaccmulate and are not biopersistent,although the water and oil repellencies of these short-chain perfluoroalkyl derivatives are significantly reduced and industrial applications are limited.Therefore,more research has focused on developing environmentally friendly and nontoxic alternative fluorinated surface treatment agent basing on short-chain perfluoroalkyl at present,aiming to replace the traditional long-chain perfluoroalkyl polymers associated with PFOA or PFOS.In view of the molecule construction of short-chain perfluoroalkyl,we designed and synthesized monomers with double perfluoroalkyl by the synergistic action of the fluoroalkyl-fluoroalkyl groups,followed by obtained of low surface energy treatment agent.At the same time,the aromatic ring was introducted as bridge-group into the monomers.It was believed that the rigid aromanic ring,which possesses a conjugate plane,might be beneficial to the regular arrangement of the fluoroalkyl side chains onto the surface,and thus provide better surface properties such as better water and oil repellent properties.In this dissertation,we have synthesized monomers with double short-chain perfluoroalkyl,followed by preparation of acrylate copolymer and fluorine-containing silicone oil.Finally,these fluoroalkyl derivatives were applied on the finishing of cotton fabrics.The relationship between the structure and properties was well analyzed.The main discussions were as follows:(1)3-Perfluoro-n-butyl-2-iodo-1-propanol was obtained using perfluorobutyl iodide and allyl alcohol as raw materials via single electron transfer reaction initiating by sodium pyrosulfite,followed by deiodination–dehydroxylation reaction and single electron transfer reaction again to give the intermediate of 1,3-Perfluoro-n-butyl-2-iodo-propane.The target product 4,4-Bis(perfluorobutyl-methylene)-1-butene and 4-Bis(perfluorobutyl-methylene)-methane-1-styrene were synthesized through Grignard reaction using the above intermediate with Grignard reagents.The structure of the target products together with intermediates was characterized by FTIR and ~1H NMR techniques.(2)Silanes functionalized with Bis-fluoroalkylated were synthesized by hydrosilylation using trichlorosilane,4,4-Bis(perfluorobutyl-methylene)-1-butene or4-Bis(perfluorobutyl-methylene)methine-1-styrene as raw materials.The structure of synthesized compounds was confirmed by FTIR and ~1H NMR.Then two types of monolayer films were fabricated on silicon wafers by the method of single molecule self-assembly technique,and the surface hydrophobic and oleophobic properties of self-assembled films were studied.XPS and AFM were used to characterize the element distribution and the morphology of the SAMs surface.The results showed that the fluoroalkyl tended to migrate from the internal of the monolayers to the outermost surface in the heat-treatment and fluorine was then riched in the surface.The contact angles showed that the heat-treatment and the introduction of the rigid bridge-group can decrease the resulting surface free energy and increase the liquid repellency of the self-assembled monolayers.(3)Firstly,1H,1H,2H,2H-perfluorooctyl acrylate(TFOA)was synthesized by esterification between 1H,1H,2H,2H-perfluorooctanol and acrylic.Then using the obtained acrylate(TFOA),4,4-Bis(perfluorobutyl-methylene)-1-butene and 4-Bis(perfluorobutyl-methylene)methine-1-styrene as monomers,three types of fluorinated polyacrylates(named PTFOA,PABFB and PABFS)were prepared via emulsion co-polymerization and applied on finishing of cotton fabrics.The polymerization and finishing were optimized by discussing the effect of the fluorine content and the concentration of the finishing agent.The water repellency properties of the fluorinated polymer emulsions and treated cotton fabrics were analyzed.By comparing with the mono-fluoroalkyl derivative,it was found that the polymer with two short-chain perfluoroalkyl groups packed on one carbon or with a rigid phenylene as bridge-group would provide better liquid repellent efficiency,which close to the long-chain perfluoroalkyl PTFOA.(4)Using methydichlorosilane,4,4-Bis(perfluorobutyl-methylene)-1-butene and4-Bis(perfluorobutyl-methylene)methine-1-styrene as raw materials,two types of fluoroalkyldichlorosilanes were synthesized by hydrosilylation followed by preparation of fluoroalkyl aminosilicone oil.The product was emulsified and applied on finishing of cotton fabrics and the surface structure of the fabric was analyzed by FTIR,SEM and XPS.The performance of fluorosilicones with different brige-group on the side-chain was studied through comparing the resulted contact angle.The result showed that introduction of phenylene as bridge-group can improve the water-repellant performance of fluorosilicone oil.