| Polytetrafluoroethylene(PTFE)has excellent properties such as corrosion resistance,electrical insulation,heat resistance and low coefficient of friction,and is widely used as anti-corrosion materials,biomedical materials,antisticking materials,insulating materials and engineering plastics.However,PTFE has the shortcomings of surface inertness and low surface energy,resulting in problems such as poor surface wettability and adhesion properties,which limit its application.In order to expand the application range of PTFE,it is necessary to modify its surface and endow it with new surface properties.Surface graft polymerization initiated by ultraviolet light has the advantages of fast processing speed,simple operation,no damage to the bulk properties of substrate,and temporal/spatial controllablability,which has been commonly used for surface modification of polymer materials.Due to the high C-F bond energy of PTFE,it is difficult to modify its surface with traditional UV grafting methods.In this thesis,organic amine solution is used as the reaction liquid to achieve the photochemical surface modification of PTFE film.The thesis main results are as follow:1.The surface modification of PTFE film is achieved by using organic amine solution under ultraviolet light irradiation.The effects of different solvents,different organic amine compounds,solution concentration,and irradition time on the modification reaction were explored.It was found that when the N,N-dimethylformamide(DMF)solution of ethylenediamine,diethylenetriamine,and triethylenetetramine were used for modification,the hydrophilicity of the PTFE film was significantly improved.Among them,the DMF solution of triethylenetetramine has the best modification effect on the PTFE film.When the ultraviolet light intensity(254 nm)was 21000 ?W/cm2,the water contact angle of the PTFE film decreased to 50° after modification with 60 wt%triethylenetetramine in DMF solution for 9 min.Infrared spectroscopy tests showed that C=C groups were introduced on the surface of the modified PTFE film.X-ray photoelectron spectroscopy(XPS)results showed that the F content of the modified sample decreased to 16.71%after 19 minutes of modification.After the modified PTFE and stainless steel are bonded with epoxy resin,the peel strength is higher than 11 N/cm,which is more than 10 times higher than the peel strength of the blank sample.A patterned modified PTFE film was prepared using a photomask.The Time-of-Flight Secondary Ion Mass Spectromtry(TOF-SIMS)test proved that the modification reaction only occurred in the illuminated area,and there were NH2-and CN-fragments on the modified surface.A striped silver pattern was successfully deposited on the surface of the patterned modified PTFE film by electroless plating.The DMF solution of triethylenetetramine was used to achieve the UV photochemical surface modification of perfluoroethylene propylene copolymer(FEP)film.When the ultraviolet light irradition intensity is 15000 ?W/cm2 and the 60 wt%triethylenetetramine solution in DMF is modified for 19 minutes,the surface water contact angle is reduced to about 10°,and the surface energy is stable between 50 and 55 mN/m.XPS results show that the F content after modification is reduced to 0.68%(the F content of the unmodified sample is 68.81%).2.The UV photochemical surface modification of the PTFE film was achieved by adding acrylic acid and acrylamide into the DMF solution of ethylenediamine.When the ultraviolet light irradition intensity is 15000?W/cm2,and 15%acrylic acid is added to the DMF solution of 60 wt%ethylenediamine,the water contact angle of the PTFE film decreases to about 40° after 9 minutes of illumination.XPS results show that F content on the surface of the film was reduced to 12.24%(the F content of the modified sample without acrylic acid was 39.7%)after 19 minutes of illumination.The DMF solution of 60 wt%ethylenediamine was added with 10%acrylamide,and the F content of the film surface after modification for 19 minutes decreased to 12.43%.The DMF solution of N,N-dimethylaminoethyl methacrylate(DMAEMA)was used to achieve the UV photochemical surface modification of PTFE.When the ultraviolet light intensity is 15000 ?W/cm2,the surface energy of the PTFE film is higher than 40 mN/m after the DMF solution of 40 wt%DMAEMA is modified for 9 min,which is more than 4 times higher than that of the blank sample.XPS results showed that the F content of the film surface after 19 min of modification decreased to 7.42%;infrared spectroscopy results showed that the characteristic absorption peak of carbonyl group appeared at 1725 cm-1,which proved the successful realization of the modification reaction.This process is expected to provide a new idea for photochemical modification of PTFE. |
PDF Full Text Request