Abstract
Optically transparent polyimide (PI) films with good dielectric properties and long-term sustainability in atomic-oxygen (AO) environments have been highly desired as antenna substrates in low earth orbit (LEO) aerospace applications. However, PI substrates with low dielectric constant (low-Dk), low dielectric dissipation factor (low-Df) and high AO resistance have rarely been reported due to the difficulties in achieving both high AO survivability and good dielectric parameters simultaneously. In the present work, an intrinsically low-Dk and low-Df optically transparent PI film matrix, poly[4,4′-(hexafluoroisopropylidene)diphthalic anhydride-co-2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane] (6FPI) was combined with a nanocage trisilanolphenyl polyhedral oligomeric silsesquioxane (TSP-POSS) additive in order to afford novel organic–inorganic nanocomposite films with enhanced AO-resistant properties and reduced dielectric parameters. The derived 6FPI/POSS films exhibited the Dk and Df values as low as 2.52 and 0.006 at the frequency of 1 MHz, respectively. Meanwhile, the composite films showed good AO resistance with the erosion yield as low as 4.0 × 10−25 cm3/atom at the exposure flux of 4.02 × 1020 atom/cm2, which decreased by nearly one order of magnitude compared with the value of 3.0 × 10−24 cm3/atom of the standard PI-ref Kapton® film.
Highlights
Flexible antennas play important roles in low-earth orbit (LEO) spacecraft for spaceearth communications, data transmission, and navigation [1]
For the common polyimide (PI) substrates derived from pyromellitic anhydride (PMDA) and 4,40 -oxydianline (ODA) (PIPMDA-ODA ), which are most widely used at present in spacecraft antennas, as shown in Figure 1, the molecular structure
We developed a series of atomic oxygen (AO)-resistant PI aerogels for the potential antenna applications from biphenylenetetracarboxylic dianhyk dride (BPDA), DMBZ, an aromatic diamine containing pendant polyhedral oligomeric silsesquioxane (POSS) units, and a POSS-containing crosslinker, Recently, Meador and coworkers reported the pioneer of ultra-low-D PI aerogels as substrates for lightweight pa ospace applications [19,20]
Summary
Flexible antennas play important roles in low-earth orbit (LEO) spacecraft for spaceearth communications, data transmission, and navigation [1]. The spaceborne antennas will contact the LEO environments in the whole life of the spacecraft. The severe space environments in LEO, including atomic oxygen (AO), thermal shock cycle in the range of −120 ◦ C~150 ◦ C, ionizing radiation, micrometeoroids, and so on will inevitably deteriorate the antenna materials, especially the common light-weighted polymeric or polymer composite antennas [2,3,4,5]. 7.9 km/s, the impact energy between the collision of polymer antennas and the AO species might be as high as 5 eV. This usually causes severe corrosion of the polymer substrates in the antennas due to the dissociation of chemical bonds in the polymers by the highenergy impacts [6,7,8,9,10]. For the common polyimide (PI) substrates derived from pyromellitic anhydride (PMDA) and 4,40 -oxydianline (ODA) (PIPMDA-ODA ), which are most widely used at present in spacecraft antennas, as shown in Figure 1, the molecular structure
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