Synthesis Of Fluorine-containing Polyacrylate Latex With High Performance And Modeling On The Antifouling Capability Of Waterborne Fluorine-containing Coating

Fluoropolymers have been widely used in the fields of coatings, spinning and leather due to their excellent weather resistance, anticorrosive ability and solvent resistance. The synthesis of fluoropolymers and the relation between the polymer molecular structures and its properties are very interesting and have always been received much attention. Thus the study on the preparation and properties of fluoropolymers is remarkable. Fluorine-containing coatings have been widely used in the fields of architecture, industry coatings, anti-rust, family upholsters and printing, hence they are indispensable, today. Solvent coatings are not only polluted environment, harmed healthiness and broken entironment, but also led to tremendous waste of resources. With the establishment of environmental law and increment of consciousness in environmental conservation, it is necessary to look for green technologies for the preparation of environmental fluoropolymers. Emulsion polymerization is one of the most important methods to prepare the fluoropolymers with excellent and environmental properties. There are many advantages of the above synthesis method, such as, easy thermolysis, high reaction speed, high molecular weight, easily control and usable straightly of the emulsion. Thus, the major works in the section of synthesis of the thesis are studied on the preparation of fluoropolymer with their controlled latex structure by emulsion polymerization method.Considering the environment and home requirement, fluorine-containing emulsions, the key component of the waterborne fluorine-containing coatings, were chosen as direction. The environmental fluorine-containing emulsions were prepared and characterized through different methods and ideas, and then studied the applications of the environmental fluorine-containing emulsions in the waterborne fluorine-containing coatings. It could provide basic academic in applications for developing the waterborne fluorine-containing coatings with high properties, environmental friendly, and independent intellectual property rights. This work is very significant for the theoretic and experimental study of new fluorine-containing coating materials and the development the theory of fluorine-containing coatings study. Developments of environmental friendly waterborne fluorine-containing coatings are more practical, economical and social.In second chapter, PTFE-polyacrylate core shell latex has been synthesized. First, PTFE powder was pre-emulsified with fluorocarbon surfactant in water and dispersed under high shear stirring, and then the pre-emulsified PTFE is used in the acrylate copolymerization. Through the study of synthesis technology, the optimized reaction conditions such as monomers ratio, composite surfactant component, and reaction temperature, the content of PTFE has been confirmed, and obtained nano core shell latex particles. Fluorocarbon surfactant plays a crucial role in the preparation of PTFE-modified polyacrylate emulsion. The emulsification ability of fluorocarbon surfactant to PTFE in the emulsion and the effect of the amount of the fluorocarbon surfactant on the particle size distribution and stability of emulsion have been investigated. In addition, a possible mechanism of fluorocarbon surfactant in polymerization based on experiments was proposed. The resulting PTFE-polyacrylate core-shell nanoparticles can not only keep PTFE original structure but also improve the compatibility of PTFE with other materials. Hence they could display adequately PTFE excellent properties and be more widely applied in multifarious fields.In third chapter, PTFE-polyacrylate core-shell nanoparticles are synthesized by simple emulsifier-free seeded emulsion polymerization of acrylate on the surface of PTFE particles. To optimize the polymerization conditions and investigate the structure and properties of PTFE-polyacrylate core-shell nanoparticles, the PTFE-polyacrylate have been characterized by various methods such as Fourier-transform infrared (FTIR) spectrometry, transmission electron microscopy (TEM), dynamic light scattering analysis (DLSA) and water contact angles, etc. The resulting PTFE-polyacrylate core-shell nanoparticles can not only keep PTFE original structure and improve the compatibility of PTFE with other materials but also avoid the disadvantageous effect of emulsifier on performance of the products. Accordingly, PTFE-polyacrylate core-shell nanoparticles prepared by this approach could have good prospect and wide application in various fields.In fourth chapter, one uniform core-shell fluorine-containing polyacrylate latex particles containing fluorine-containing polymer rich in shell were prepared successfully by emulsifier-free seeded emulsion polymerization of fluorine-containing acrylate and fluorine-free acrylate monomers with PMMA as seeds. Two kinds of emulsifier-free core-shell IPN fluorinated polyacrylate latex nanoparticles containing fluorine in shell were successfully synthesized by emulsifier-free seeded emulsion polymerization of fluorinated methacrylate and crosslinker surrounding crosslinked polyacrylate core with water as the reaction medium. The reactive emulsifiers used here containing polymerizable double bond can react with monomers and become a part of the copolymers, which can not only provide the stability of the latexes but also avoid the negative effects of general emulsifiers on the properties of the latex films. The fluorinated copolymer can be fixed on the particle shell layer to avoid migration of fluorine to the inside of particles due to the formation of the interpenetrating polymer network. The obtained emulsifier-free core-shell IPN fluorinated polyacrylate latexes are stable, and the excellent properties of the fluorine can be shown. TEM and DLS analyses have effectively proved the formation of the core-shell structure particles and very narrow monomodal particle size distributions. FTIR spectra and XPS analysis confirmed that fluorinated acrylate monomer could be introduced into the latex particles through emulsifier-free seeded emulsion polymerization. Furthermore, XPS analysis of the latex films revealed that fluorinated groups had the tendency to enrich at interface. The result of static contact angle measurement indicated the contact angle of the hydrophobic emulsifier-free core-shell IPN fluorinated polyacrylate film increased with increasing the amount of fluorinated groups. In addition, compared with the latex film of crosslinked polyacrylate, the emulsifier-free core-shell IPN fluorinated polyacrylate latex film showed lower water uptake and higher thermal stability. The emulsifier-free seeded emulsion polymerization is a potentially promising method in preparing environment friendly core-shell IPN fluorinated polyacrylate nanoparticles.In fifth chapter, the mechanical evaluation of bonding strength between coating and substrate was performed via finite element method (FEM), and a modified test model was proposed. The maximum shear stress and the maximum tensile stress on the coating and substrate interface were analyzed. The influences of the step depth of model,dimensions of coating and the material properties of coating and substrate on the interface bonding strength of coating-substrate was compared and an optimum model has been selected. The maximum tensile stress was obviously decreased in this model, and then the change of shear stress in different systems could be distinctly shown. Subsequently, the interface bonding strength in different systems was investigated.In the last chapter, the environmental friendly waterborne fluorine-containing coatings were prepared, and the effects of PVC and fluorine contention on the properties especially the fouling resistance of coatings were investigated. When PVC below CPVC, the fouling resistance of coatings could be improved with the increment of PVC. However, when PVC above CPVC, the fouling resistance of coatings fell down with the increment of PVC. In addition, the fouling resistance of coatings was improved, when the contention of fluorine increased. Mathematics model of the fouling resistance of coatings was designed. In this thesis, various kinds of emulsifier-free core-shell fluorine-containing polyacrylate latexes were synthesized successfully by emulsion polymerization for the first time. And the emulsifier-free core-shell fluorinated polyacrylate latexes were applied in the waterborne fluorine-containing coatings. The resulting emulsifier-free fluorine-containing polyacrylate latexes can not only present excellent physical and chemical properties with low fluorine content but also avoid the disadvantageous effect of emulsifier on performance of the products, save energy and sources, environmental friendly and belong to green chemistry. It also could provide basic academic in applications for developing the waterborne fluorine-containing coatings with high properties, environmental friendly, and independent intellectual property rights.