Preparation and Atomic Oxygen-Resistant Properties of Quaternary Ammonium Salt Modified Polyhedral Oligomeric Silsesquioxane/Polyimide Composite Fibers

Herein， polyhedral oligomeric silsesquioxane （POSS） nanoparticles were modified by quaternary ammonium， followed by adding into polyamic acid （PAA） spinning solution. Then series of QA-POSS/PI composite fibers were afforded via wet-spinning process. The as-prepared composite fibers showed good thermal properties with 5% thermal decomposition temperature （T5%） and glass transition temperature （Tg） values of 558 ℃ and 395 ℃. Based on X-ray photoelectron spectroscopy （XPS） and inductively coupled plasma （ICP） measurement results， the silicon contents on fiber surface were higher than those in total fiber， which indicated that silicon showed gradient distribution in composite fibers. When additive amount of QA-POSS nanoparticles was raised from 0% to 15%， the surface topographies of composite fibers displayed a clear change from roughness to compact， and mass loss decreased obviously from 1.40 mg/cm2 to 0.10 mg/cm2 after AO erosion with the fluence of 3.17×1020 atoms/cm2. Actually， the lowest loss of mechanical properties was seen for the composite fibers when 5% QA-POSS particles were added. Fracture strength and initial modulus retentions of the fibers were 89.36% and 89.35%， respectively. And the corresponding decay rate of the strength was seen as 1.58×10-13 Pa·cm2/atom.