| Perfluoropolyether is a kind of high performance perfluoropolymer, which not only shows high thermal stability, oxidative stability and good chemical inertness in lubricants,but also has the main chain of ether bond,which is more flexible than other polymers. It is widely used in construction, electrical and electronic, military and aerospace and other fields. But the perfluoropolyether has poor adhesive with glass, metal and ceramics. It is necessary to modify perfluoropolyether with organo-siloxane, acrylate and isocyanate to improve the adhesion of perfluoropolyether and substrates. In particular, silicone modified perfluoropolyether, not only has excellent properties of hydrophobic and oleophobic, high and low temperature and self-cleaning, also safe,reliable, non-toxic, non-polluting,non-corrosive, aging resistance and long service life. Therefore, it is important to study the perfluoropolyether modified by organo-siloxane.Currently, ammonolysis and hrdrosilylation are fashionable methods to prepare perfluoropolyether siloxane. In this thesis, pentaerythritol triacrylate silane modified perfluoropolyether was prepared by using perfluoropolyether carboxylic acid,pentaerythritol triacrylate and 3-aminopropyltriethoxysilane as functional monomers, which structure was characterized by FT-IR. The effects of preparation conditions on the properties of the coatings were investigated. When the baking temperature was 160?,baking time was 60min and the mass fraction of perfluoropolyether siloxane coating agent was 0.10%, the initial contact angle of water reached 118° . But the contact angle of water was decreased 100° rapidly after rubbing with steel wool for 100 times, under 1 035 g load.The results showed that polar siloxanes were grafted in the molecular chains of perfluoropolyether which could seriously affect the abrasion resistance property of coatings.In order to further research, perfluoropolyether siloxane was prepared by hydrogen siloxane and perfluoropolyether allyl ether,which was synthesized by perfluoropolyether alcohol and allyl chloride. The structures of products were characterized by FT-IR and 1HNMR. The effects of molecular chain structure and film forming conditions on the hydrophobicity and hydrophobicity of the coatings were investigated. The results show that the initial contact angles of water and n-hexadecane of Z-perfluoropolyether siloxane coating are 113° and 65 ° , respectively, which is lower than that of K-perfluoropolyether siloxane under the same film forming conditions. They differ by 3°? 5° and 5° ?7°.The contact angle of n-hexadecane of the a-terminated Z -perfluoropolyether siloxane is higher than that of ?, ?-terminated Z-perfluoropolyether siloxane, which shows that CF3 group can improve the surface properties of coating.In this paper, the influence of molecular structure, siloxane content, molecular weight and additives on the abrasion resistance of the coating was discussed. The results show that high molecular weight,high flexibility chain and high siloxane content can improve the abrasion resistance of coating. Under the same conditions, the water contact angle of the Z-perfluoropolyether siloxane coating kept over 100° after rubbing with steel wool for 2,500 cycles,which was 1000?1500 cycles more than that of the K-perfluoropolyether siloxane. The content of siloxane can improve the degree of attachment of the perfluoropolyether molecular chains to the glass surface. When the coating is subjected to frictional loss, the longer the molecular chain of perfluoropolyether is, the more time for energy transfer to adjust the conformation. Isopropanol as a additives, can improve the stability of coating, and broaden the area of stable change, thereby improving the coating's wear resistance. |
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