Preparation And Properties Of Ultrathin Polyethersulfone Films Driven By Dynamic Bond

As a new type of functional material,polymer film has good development prospects and wide application space,and is widely used in aviation,aerospace,sealing,microelectronics,protective layer and other fields.In some cutting-edge fields,due to application conditions,not only have certain requirements for the thickness of the film,but also require the film to have higher thermal properties and better mechanical properties.Polyethersulfone（PES）,as one of the high-performance engineering thermoplastic materials,has attracted the attention of researchers because of its good mechanical properties,heat resistance and chemical stability.However,there are few reports on the preparation of ultra-thin films based on polyethersulfone.Therefore,the design and preparation of ultra-thin,high-strength polyethersulfone film materials is a research work that promotes scientific and technological progress.The purpose of this thesis is to obtain nano-level ultra-thin polyethersulfone films,using 4-hydroxybenzotriazole and 4-hydroxyindole as raw materials,and reacting with 4,4’-difluorodiphenylsulfone to prepare two a variety of different structures of polyethersulfone,poly（ethersulfone benzotriazole）（PESB）and poly（ethersulfone indole）（PESI）,and the spin coating method was used to prepare ultra-thin films of the obtained polymer.The performance of the ultra-thin film is enhanced by metal coordination and cation-πinteraction,and a polyethersulfone film with excellent performance is obtained.At the same time,its strengthening mechanism is analyzed.In addition,the PESI film is hydrophobically treated to obtain better hydrophobicity effect.The specific results are as follows:The polymer PESB was prepared with 4-hydroxybenzotriazole and4,4’-difluorodiphenylsulfone as raw materials,and the structure of PESB was characterized by infrared and hydrogen nuclear magnetic spectroscopy.Spin-coating method is used to prepare ultra-thin films,and PESB ultra-thin films of different thicknesses are prepared by adjusting the process conditions（polymer concentration and spin-coating speed）.After immersing the film in a 0.1 M Cu SO₄solution for 18hours,the performance of the film is greatly improved.The tensile strength of the unsoaked Cu²⁺PESB ultra-thin film is 75.84 MPa,and the elongation at break is3.93%.The tensile strength of the soaked polymer ultra-thin film(PESB-Cu²⁺)is105.38 MPa,and the elongation at break is 4.83%.,Before and after comparison,the tensile strength increased by 25.45 MPa,and the elongation at break increased by0.9%.Computer simulations show that the reason for the improved performance is the metal coordination between the PESB ultra-thin film and Cu²⁺.The polymer PESI was prepared with 4-hydroxyindole and4,4’-difluorodiphenylsulfone as raw materials,and the structure of PESI was characterized by infrared and hydrogen nuclear magnetic spectroscopy.Spin-coating method is used to prepare ultra-thin films,and PESI ultra-thin films of different thicknesses are prepared by adjusting the process conditions（polymer concentration and spin-coating speed）.After immersing the ultra-thin film in a 0.1M Mg Cl₂solution for 12 hours,the performance of the film is greatly improved.The tensile strength of the unsoaked Mg²⁺PESI ultra-thin film is 70.57 MPa,and the elongation at break is4.01%.The tensile strength of the soaked polymer ultra-thin film(PESI-Mg²⁺)is102.93 MPa and the elongation at break is 5.13%.,The tensile strength increased by32.36 MPa,and the elongation at break increased by 1.12%.Computer simulations show that the reason for the performance improvement is the cation-πinteraction between the PESI ultra-thin film and Mg²⁺.In addition,PESI was subjected to Si O₂hydrophobic modification treatment,and good modification results were obtained.When the Si O₂content is 20%,the material has the best hydrophobic performance,and the water contact angle reaches 146o.