Synthesis And Properties Of Fluorine Modified Hyperbranched Waterborne Polyurethane

The ratio of hard and soft segments in polyurethane can be modulated, so the product of polyurethane can be manufactured both very hard or very soft with good flexibility, and the polyurethane also has good biocompatibility, which make the polyurethane widely used in coating, adhesive, engineering components, elastomers and biomedical materials. The dispersion medium of aqueous polyurethane is water, so it has the advantages of no pollution, no toxic, easy to transport and so on. In recent years, with the enhancement of people’s environmental awareness and the limit of national laws and regulations, water-based polyurethane has the trend of replacing solvent-based polyurethane. Because aqueous polyurethane has good performance, it has been widely used in paints, adhesives and other industries. In the synthesis process of aqueous polyurethane need to introduce hydrophilic groups into the molecular chain, thereby improving the water-dispersible of polyurethane, but this can reduces the water resistance of aqueous polyurethane. To compensate for these deficiencies, strongly hydrophobic group can be introduced into aqueous polyurethane, especially introducing fluorocarbon segment to increase its water resistance. Hyperbranched polymer has a large number of end groups and various modifications can be done to prepare excellent hyperbranched polymer products. Hyperbranched polyurethane not only has the general advantages of hyperbranched polymer, such as low viscosity, low melting point, easy to dissolution, multiport functional groups, molecular chain without tangles, etc. but also has the advantages of polyurethane, such as good abrasion resistance, thermal stability, flexibility and solvent resistance and other characteristics.The first chapter introduces three main methods of synthesis of hyperbranched polyurethane:single monomer methodology, double monomer methodology and hyperbranched polymer methodology. Then the degree of branching is introduced, which is the main characterization of hyperbranched polyurethane, and its test method and definition is mentioned. Hyperbranched polyurethane has special properties, so it has particular applications in many aspects, such as hyperbranched polymer coatings, damping materials, solid polymer electrolyte and shape memory material. Finally, the modifications of acrylate and organic fluoride in waterborne polyurethane are introduced.In the second chapter, hyperbranched polyurethane (HBPU-0) was prepared from isophorone diisocyanate (IPDI), dimethylol propionic acid(DMPA) and diethanol amine(DEOA), and linear polyurethane was prepared from IPDI, polyether polyol(N220), DMPA and hydroxyethyl methacrylate(HEMA). Linear polyurethane was grafted to HBPU-0, after-COOH neutralization reaction with three triethylamine (TEA) and become salt, dispersed in water, and finally add ethylenediamine (EDA) as the chain extender in water, and then react with hexafluorobutyl methacrylate(HFMA) then the organic fluorine modified hyperbranched waterborne polyurethane was obtained. Using IR and 13C NMR to characterize the polymer, and studies the organic fluorine content of polymer emulsion particle size, stability and film mechanical properties, contact angle, water absorption and heat resistance effect. The results show that with the increase of organic fluorine content, contact angle, tensile strength and emulsion particle size increased, water absorption and breaking elongation decreases. When organic fluorine was added, heat resistance of film becomes better. When the organic fluorine content is 10%, the film has the best mechanical properties, the emulsion particle size is 145nm, water contact angle is 93.4°, the tensile strength is 11.7MPa, and elongation at break is 360%, water absorption of 48 hours is 6.12%.In the third chapter, linear polyurethane was mainly prepared from toluene diisocyanate(TDI), polyether polyol(N220), DMPA and hydroxyethyl methacrylate(HEMA). Then homemade hyperbranched polyurethane core HBPU-0 was added as cross-linking agent. After the steps of neutralization, chain extension and emulsification, then radical polymerization with organic fluorine monomer and acrylate monomer was occured. Then the organic fluorine and acrylate modified hyperbranched waterborne polyurethane(FHBPUA) was obtained. IR shows organic fluorine has been access to the polyurethane. After the addition of the organic fluorine, the heat resistance and hydrophobicity of FHBPUA are both improved. Through a series of tests shows that with the increase of organic fluorine content, the emulsion particle diameter and the tensile strength increased, the elongation at break and the water absorption decreased. When the organic fluorine content is 10%, the overall performance of FHBPUA is better, in which case its emulsion particle size 120nm, tensile strength is 13.1MPa, elongation at break of 403.2%,24h water absorption was 5.89%.In the fourth chapter, the fluorinated diol DEFA which has long branched structure was first synthesized. Using DEFA partly instead of small molecule chain extender to synthesis linear polyurethane prepolymer, then added homemade hyperbranched polyurethane HBPU-0 as the cross-linking agent, and finally react with ethylene diamine as chain extender. Then fluorinated diol-modified hyperbranched waterborne polyurethane (FHBPU) emulsion was synthesized. IR shows that DEFA has been accessed to the hyperbranched polyurethane. After adding DEFA, the heat resistance and hydrophobicity of FHBPU are improved. Through a series of tests shows that with the increase of DEFA content, particle size of emulsion and tensile strength increase, the elongation at break and the water absorption decrease. When DEFA content is 10%, the overall performance of FHBPU is better, in which case its emulsion particle size 131 nm, a tensile strength of 10.8MPa, elongation at break of 368.4%,24h water absorption of 5.4%.