Enhancing the Performance of Flexible Polyimide Aerogels by Structural Tuning via Freeze‐Drying and Water‐Soluble Crosslinker Design

ABSTRACT This research addresses the limited flexibility of polyimide (PI) aerogels by developing an innovative, cost‐effective, and environmentally friendly preparation method. By combining freeze‐drying technology with melamine, a water‐soluble crosslinker, the microscopic structure is refined through controlled ice crystal morphology and arrangement. This optimization significantly improves the aerogel's mechanical properties and flexibility. Melamine enhances intermolecular bonding, achieving a balanced combination of rigidity and flexibility. The successful crosslinked structure is confirmed using infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and x‐ray photoelectron spectroscopy (XPS). The resulting PI aerogel demonstrates exceptional mechanical strength, with a compressive strength of 0.49 MPa and only 15% height loss after 10 cycles of 50% strain compression. Additionally, it exhibits outstanding thermal stability (thermal decomposition at 390°C) and superior insulation performance (thermal conductivity of 0.03 W/mK). This research introduces a novel strategy integrating liquid freezing and crosslinker design, paving the way for advanced PI aerogel applications in flexible materials, thermal management, and high‐temperature insulation while offering valuable insights for cost‐effective, high‐performance aerogel development.