| Although anionic PU emulsions are often encountered in the literature, therehave been not many reports about the preparation and the properties of thecationic PU, which show very high adhesion to various ionic substrates,especially anionic substrates such as paper, leather, textile, coatings and adhesive.Some inferior properties of traditional waterborne polyurethanes (WPU) such aslow mechanical strength, water and solvent resistance restrict utility for highperformance applications of WPU. It is important to modify the WPU byintroducing hydrophobic chain segments or cross linked structure into WPU.Fluorocarbon chains can be incorporated into polyurethane via fluoro-containingdiisocyanates, polyether glycols, polyester glycols and chain extender, always bystep polymerization. Perfluorinated acrylate was chose to preparepolyurethane-fluorinated acrylic hybrid emulsions by radical copolymerization inour study system. As an alternative to the step polymerization, free radicalcopolymerization has emerged as an attractive and simple method for producingfluorinated polyurethane. First, preparation and properties of cationic waterbonepolyurethane were studied. Then the cationic polyurethane-perfluorinatedacrylate hybrid emulsions were prepared by physical compound method andchemical crosslink method, respectively. Structures and properties of hybridemulsions latexes and their films were studied, which could provide fundamentalinformation for film-forming performance and operational performance ofcationic polyurethane-perfluorinated acrylate hybrid emulsions.A serial of selfcrosslinked and selfemulsifying polyether cationicpolyurethane (CPU) emulsions were prepared by usingpolytetrahydrofuran glycol (PTMG1000) as soft segment, N-methyl diethanol amine (MDEA) as cationic chain-extender and trimethylolpropane (TMP) asinner crosslinker.The CPU emulsions were modified with the hydrophobic perfluorinatedacrylate (FA) by the physical compound method. In the cationic polyurethanesprepolymer preparation step, the vinyl monomer mixture was added in order toreduce the high viscosity of reactive system instead of traditional organic solvent.There was no small molecule emulsifier used in the perfluorinated acrylateradical copolymerization step which relied on the cationic group of CPU tosupply hybrid emulsion stability and belong to emulsifier-free polymerization.The cationic polyurethane prepolymer were prepared with MDEA as hydrophilicchain extender, TMP as innercrosslinker and the perfluorinated acrylate and theother vinyl monomer as diluter instead of traditional solvent. After theneutralization and dispersion of the prepolymer, the PU emulsion swollen byvinyl monomer obtained, which acted as the seed emulsion and the vinylmonomer swollen in PU latexes took place radical copolymerization in it andthen the cationic polyurethane-perfluorinated acrylate hybrid emulsions (PUFA)were obtained.On the basis of CPU modified with perfluorinated acrylate, the properties ofhybrid polymer were tried to been raised by crosslink structure. The aqueouscationic polyurethane dispersion was prepared by using tertiary amine group tomake the polyurethane dispersible and then nanograde core-shell and crosslinkedstructure FAPU hybrid emulsions containing perfluoroalkyl side-chains wereobtained from double bond-end capped polyurethane macromonomers withperfluoroalkyl acrylate by radical copolymerization.The results showed the mechanical strength, water resistance and the heatstability of the hybrid films enhanced. The hybrid films showed excellent surfaceproperties due to the introducing of the perfluorinated group. The surface freeenergy of the hybrid films were about 20mJ/ m2,which was lower the surfacefree energy of water (72.8mJ/m2)and common oil (25-35mJ/ m2),so the hybridfilms had the water and oil repellent properties. The study results also showedthat the surface free energy could be reduced under the higher heat treattemperature. Through surface morphology observation of atomic forcemicroscope (AFM), it can be seen that the surface morphology of smooth overall but micro-rough was formed. X-ray photoelectron spectroscope (XPS) analysisshowed that the practical content of fluorine on the perfluorinated polymermembrane surface was much higher than the theoretical value which indicatedthat perfluoroalkyl chains had significant enrichment to the surface. Apreliminary study of the application performance of FAPU on paper surfacesizing proceeded at last. The better technology was: the sizing emulsion solid ofFAPU was 3‰, the annealing temperature was 120℃and the annealing timewas 3 minutes. The water and liquid paraffin contact angles of the paper treatedby the FAPU hybrid emulsion with 30% FA content were 132 o and 108 o,respectively. The contact angles almost changed nothing during 5 minutes. Allthese showed that the papers treated with the hybrid emulsion possessed goodwater and oil repellent properties.
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