High thermal conductivity and low absorptivity/ emissivity properties of transparent fluorinated polyimide films

Polyimide film materials are a very promising and high-performance polymer in space application. However, the deep coloration of conventional polyimide films greatly limits the wide use in areas where transparency and low solar absorptance are the essential requirement. Here, we prepared the transparent polyimide from 4,4\(^{\prime }\)-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and different ratios of 2,2\(^{\prime }\)-bis(trifluoromethyl)-benzidine (TFB) and 2,2-bis(4-(4-aminophenoxy)-phenyl) hexafluoropropane (BAPP) with a low solar absorptance. Properties, such glass-transition temperature, thermal decomposition temperature, thermal conductivity and transmittance, were investigated, It is suggested that the introduction of fluorine into polyimide will significantly increase transmittance and in turn decrease solar absorptance, The polyimide film with fluorinated groups exhibited superior optical transparency, low absorptivity/emissivity, high thermal conductivity, and good resistance to ultraviolet radiation. The transparent polyimide exhibits a low solar absorptivity of 0.04 and infrared emissivity of 0.6.