Enhanced UV stability of polyimide based on pendent ortho-hydroxybenzophenone UV-absorbing groups

With the trend toward lighter and longer-lasting spacecraft operating in harsh environments, developing advanced high-performance polymer materials with adequate photostability has become an urgent issue. Here, a strategy is proposed to introduce UV-absorbing units as pendent side groups into polyimide (PI) backbone to develop intrinsic PI materials through molecular structure design. Compared with direct incorporation into polymer backbone, this method has a minimal impact on diamine reactivity, enabling the preparation of PI with high molecular weights, and more effectively inhibiting initial UV degradation. The addition of only 5 % of functional monomers for copolymerization can significantly enhance UV resistance while maintaining excellent mechanical and thermal properties. Furthermore, for PI fibers, combining chemical structure with the regulation of the aggregate structure during fiber spinning and heat-drawing process can produce high-performance PI fibers with superior overall properties. Unlike the conventional addition of inorganic nanoparticles or organic UV absorbers, this work aims to establish the relationship between chemical structure, material properties, and UV degradation mechanism. It provides a novel approach from the perspective of molecular structure design for advanced high-performance polymers that require complex processing and stringent performance demands, including long-term UV resistance and mechanical performance.