Bifunctional silicone triggered long-range crosslinking phenolic aerogels with flexibility and thermal insulation for thermal regulation

•The bifunctional silicone endows the molecules more feasibility by chain enlongation.•The synergistic adjustment for flexibility is employed.•The buffer of the precursor facilitates the mild formation of SixPRA-y.•SixPRA-y shows compressibility with good fatigue-resistance (1000-cycle-40% strain).•SixPRA-y exhibits superior hydrophobicity with a lotus effect.•The assembled thermal regulator enables dynamic thermal management through deforming. Lightweight and flexible aerogels are highly demanded for thermal management in the burgeoning aerospace and artificial intelligence (AI) fields. However, the design and preparation of thermal insulating aerogels integrating good flexibility, low density, and superior thermostability through environmentally friendly methods remains challengeable. Herein, by introducing bifunctional silicone, a strategy of chain elongation assisted with pore structure adjustment is developed to achieve the flexibility of thermostable phenolic resin aerogel (PRA). The silicone introduction effectively suppresses the drying shrinkage, thus enabling the employment of ambient pressure drying (APD). The obtained flexible PRA combining high softness (elastic modulus 0.05 kPa), superior deformability (cyclic compressive strain > 60%, damage strain up to 80%), and good fatigue-resistance (compression at 40% strain > 1000 cycles) exhibits low bulk density (0.058 g·cm−3), and low thermal conductivity (0.033 W·m−1·K−1). With these superior properties, it can effectively serve for static thermal insulation below 200 °C with a thickness of 2–3 mm; more attractively, it can perform dynamic thermal management as a regulator through compressing and releasing (eg. temperature 41.9–57.6 °C, 0–40% compression strain, thickness of 30 mm). These merits make the material promising for AI thermal management in fields like outdoors, aerospace, and infrared camouflage.