Synthesis Of Water Repellant Agent With Side-chainfluoroalkyl Polyether And Property Finishing On Fabrics

Long-chain perfluoroalkyl(C?8)has been identified to undegrade in most environmental conditions and be harmful to the environment.Therefore,the materials with long-chain perfluoroalkyl substitution have been gradually banned.Fortunately,it was found that perfluorinated chains with carbon-chainlength to be6 or less is not bioaccmulate and are not biopersistent,although the water and oil repellencies of these short-chain perfluoroalkyl derivativesare significantly depressed and industrial applications are limited.In order to replace materials with long-chain perfluoroalkyl by short chains,side-chainfluoroalkyl polyether with short-chain perfluoroalkyl attachment was synthesized through cationic ring opening polymerization.As the molecular weight of the side-chainfluoroalkyl polyether increases,more fluoroalkyl groupsmigrated onto the surfaceand thus provided better water and oil repellent properties.Using newly synthesizedfluorinatedpropylene oxide as monomer,side-chainfluoroalkyl polyetherwas obtained and followed by preparation of acrylate copolymer and waterborne fluorinated polyurethane.The relationship between the structure and properties of self-assembled films and treated cotton fabrics was well analyzed.In addition,the mechanism and microscopic structures of silanlizedfluoropolyethers self-assembled films were investigated in depth and the preparation methods of materials with low surface free energy were studied as well.All the discussions were follows:(1)End-blocked silanization of side-chainfluoroalkyl polyether and its?surfaceproperties3-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.Subsequent epoxidation of the iodo-alcohol mediated by Na OH gives the corresponding oxirane(2,2,3,3,4,4,5,5,5-nonafluoropentyloxirane)in high yield.Then,these three novel side-chainfluoroalkyl polyethers with different molecular weight were synthesized through cationic ring-opening polymerization by using the BF3·Et2O as the catalyst.The poly[2,2,3,3,4,4,5,5,5-nonafluoropentyloxirane]glycol allylethers were synthesized by condensation of fluoroalkyl polyether and 3-bromopropene.Silanlizedfluoropolyethers were prepared and coated on silicon substrates(O2 plasma treatment)via the method of liquid phasedeposition,to provide hydrophobic self-assembled film.The structure of the fluorine containing products was characterized by FTIR and1 H NMR techniques.The surface chemical compositions and structures of self-assembled films were analyzed by X-ray photoelectron spectroscopy and the result showed that silanizedfluoropolyethershave uniformly assembled onto the surface of hydroxylated silicon substrate successfully.Water contact angles and surface free energy were tested to characterize the surface wettability of self-assembled films.The morphology obtained by AFM showed that the surface of fluoropolyether self-assembled film was rough and covered with evenly distributed sharp bulges,which formed by the immigrating of fluoroalkyl chain and microphase separating of the film after heat treatment,and thus to improve the water repellency of the surface remarkably.(2)Emulsion copolymerization and fabric finishing of side-chainfluoroalkyl acrylatePoly[2,2,3,3,4,4,5,5,5-nonafluoropentyloxirane]glycol acrylatewere synthesized by esterification between the terminated hydroxyl of fluoroalkyl polyether and acryloyl choride.Then using theobtained fluoroacrylateas monomers,three types of fluorinated polyacrylates were prepared via emulsion co-polymerization and applied on cotton fabrics finishing.The polymerization and finishing were optimized by discussing the fluorine content.The emulsion stability decreased with the increase of fluorine content because bigger particles formed.During the annealing process,the perfluoroalkyl chain migrated to the fabric-air interface and thus more fluoroalky segments accumulated to obtain the lowersurface free energy.Water contact angles of the treated cotton fabrics increased with the increasing fluorine content.(3)Synthesis of waterborne fluorine polyurethane and application on cotton fabricUsing isophoronediisocyanate(IPDI)as the hard block and the PEG-1000/fluoropolyether as the soft block,novel waterborne fluorinated polyurethane containing short fluoroalky side-chain has been prepared and applied on cotton fabrics.The anion waterborne fluorine polyurethane emulsion was tested to possses small particle size,narrow size distribution and the resulted good stability.The emulsion was used to treatthe cotton fabric and provide very good hydrophobicity with the contact angles of139.4°,and the water contact angles of the treated cotton fabrics increasewith the decreasing of PEG-1000 proportion in the soft block.