Preparation and Properties of Irradiation-resistant Transparent Polyimide

In recent years, polyimide has shown great application prospects in the fields of cover sheet for space solar cell due to its outstanding mechanical property, excellent thermal stability, light weight, easy processing and other properties. However, the transparency and irradiation-resistant properties of optically transparent polyimides need to be further improved. Herein, a new transparent polyimide film is prepared by the copolymerization of 2,2'-bis(trifluoromethyl) diaminobenzene, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and doping with fluorine-containing ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide. Magnesium fluoride and silicon dioxide antireflective films are successively coated on the surface of the polyimide film by electron beam evaporation technology, and a novel silicon dioxide/magnesium fluoride/transparent polyimide (SiO2/MgF2/CPI) composite film that can be used as cover sheet for solar cell is obtained. The investigation of the thermal, optical, mechanical and irradiation-resistant properties shows that the initial thermal decomposition temperature of this SiO2/MgF2/CPI composite film is 394.8 degrees C, the tensile strength reaches 65.81 MPa, and the light transmittance at 550 nm is as high as 93.43%. After electron irradiation with electron energy of 50 keV and irradiation fluences of 4x10(14), 2x10(15) and 4x10(15) e/cm(2), the thermal stability, light transmittance and mechanical properties of the SiO2/MgF2/CPI composite film have no significant decrease, showing excellent irradiation-resistant property and good application prospect in solar cell cover sheets of space vehicles. [GRAPHICS] .