Synthesis Of Hyperbranched Poly (Ethersulfone)s And Their Study As Coating Additives

With the development of the times, people are increasingly demanding high-performance materials, the ordinary common plastics can not meet the application of high-end products. Thus, special engineering plastics are widely researched by scientists. After years of efforts, a series of excellent structure, strong heat-resistant engineering plastics have been developed, and PES is a member of this family.PES is the first application of special engineering plastics and has a lot of excellent performances, such as heat resistance, hydrolysis resistance, impact resistance, creep resistance, non-toxic, chemical resistance. Especially, it can continuously be used at high temperature and still maintain performance in the environment which has rapid temperature changes. PES has been widely used in a number of of complex products with thin wall and highly filled composite materials. PES has widely been used in the electronic, electrical, aerospace, aviation, medical fields. Since PES has properties that strong adhesion with iron, aluminum and other metals and high hardness of the coating, so it can be applied to chemical corrosion resistance, non-stick coating equipment and other fields. However, the rheological properties of PES as a coating need to be improved. The rheological properties of coating is an important factor of film appearance and performance, and it will affect the dye in the sink to the bottom paint storage, construction leveling and sagging, and the construction of viscosity.PES has an curing to sintering process in the application of coating film. In this process,330℃is the second stage of leveling. At this stage, material depends on its own melt flow to fill the holes caused by solvent evaporation. If the material's viscosity is too higher at 330℃, the film surface will be defective, affecting the overall performance.This paper focuses on synthesizing a new hyperbranched polymer with highly branched structure, lower solution and melt viscosity characteristics which improves the rheological properties of PES, namely, solves the leveling problem at high temperature without sagging.Thesis is divided into two parts:one is the synthesis and characterization of monomer and polymer, the other is the study of hyperbranched polymer as paint additives.The first part:using the easy-to-buy 2,6 -difluorobenzene sulfonyl chloride with fluorobenzene, anhydrous ferric chloride as a catalyst, synthesized a monomer with three functional groups, and reaction activity of three fluoride in the monomer was different. Its structure was characterized by elemental analysis, IR and NMR test. After the structure is confirmed, two series of different terminated hyperbranched polymers were prepared by the above monomer and bisphenol S. One series is fluoride terminated hyperbranched polymer, and the ratios of hydroxyl groups with fluorine groups for them were 0.55,0.60 and 0.63, respectively. The other series is hydroxy-terminated polymer, and the ratios of hydroxyl groups with fluoride f groups were 1.40,1.45,1.50, and1.55, respectively. Determining the gel area is between 0.63～1.4 which was the value of hydroxyl functional groups with fluoride functional groups. After the structure was tested by IR and NMR, their performance were also tested. TGA results showed that the thermal stability of fluoro-terminated HPES (-OH:-F=0.63) was the best for F-HPES, and the thermal stability of hydroxy-terminated HPES (-OH:-F=1.40) was the best for OH-HPES. DSC results also follow the sametrend, and that the Tg of hyperbranched PES and linear PES is no significant difference. GPC test and viscosity test showed that the molecular weight of fluoro-terminated HPES (-OH:-F=0.63) was the largest for F-HPES, and the molecular weight of hydroxy-terminated HPES (-OH:-F=1.40) was the largest for OH-HPES. In order to explore the reaction mechanism of these polymers, capped, linear and branched model compounds were synthesized. The structures of these model compounds and the reaction sequence of three fluoride functional groups for the synthesized monomer were determined by 1H-NMR:first, the fluorine located at ortho-position of O=S=O group reacts with phenolic group, then the fluorine located at para-position of O=S=O group reacts with phenolic group.1H-NMR spectra of hyperbranched polymers can't clearly discriminate each peak, so 19F-NMR method was adopted to calculate the degree of branching of polymers. Using the formula DB=2NT/(2NT+NL), the degree of branching of fluoro-terminated (-OH:-F=0.63) and hydroxy-terminated (-OH:-F=1.40) HPES was 74.6% and 100%, respectively.The second part: two hyperbranched polymers with the best thermal performance and the largest molecular weight, were blended with linear PES. The two polymers are the functional groups radio of 0.63 and 1.40 that is the radio of hydroxyl functional groups with fluoride functional groups. Using the way of solution blending, four blends that hyperbranched polymers content are 0.5%,1%,2%, 3% were obtained.Because our main purpose focused on discussing the rheological properties of paint at 330℃, so the capillary flow test at 330℃for the polymers was carried out. The results showed that the addition of hyperbranched polymers can indeed reduce the melt viscosity of linear polyether sulfone, the more the polymer content was, the better the improvement of viscosity was. Fluorine-terminated and hydroxyl-terminated polymers have the same trend.Blend was prepared into the engineering required viscosity, and it could be found that the addition of hyperbranched polymers can reduce the amount of solvents at room temperature Moreover, the more the addition of hyperbranched polymer was, the less the amount of solvents was. After spraying the coating, a series of tests were carried out. First, adhesion test results show that the addition of hyperbranched polymer has little effect on aluminum adhesion when the added amount was the smaller. However, the adhesion of the film was beyond the scope of use when the added amount was more than 3%. Compared to the blends with the same added amount, hydroxyl-terminated blend's adhesion was superior to fluorine-terminated blends. Then the photographs of scanning electron microscope showed that fluorine-terminated hyperbranched polymer could improved the liquidity of the film, but the appearance of the film is not good; whereas hydroxyl-terminated polymer could improve the liquidity of the film, but also the appearance of the film is also good.,. Namelywhen a small amount of hydroxyl-terminated polymer was added, the hollow formed in the process of the solvent evaporation could not be seen. For the blend film and the pure PES film, the following performance are tested:impact resistance, acid and alkali resistance, salt resistance were tested The results showed that the addition of hyperbranched polymer has no effect on these properties. In summary, we synthesized hyperbranched polyethersulfone. The addition of hyperbranched polyethersulfone to linear polyethersulfone, really can improve the high temperature leveling, hydroxyl-terminated hyperbranched PES performance is best as additives, and the best addition value is 1%.