Superelastic Polyacrylonitrile Aerogels via Ultraviolet‐Induced Radical Crosslinking Toward Ultralight and Thermally Insulating Wearables

ABSTRACT Phase‐change aerogels promise combined thermal insulation and latent heat storage but remain limited by leakage, weak mechanics, and poor cycling durability. Here, comb‐like polyacrylonitrile‐based (PAN) copolymers are engineered by integrating hexadecyl acrylate (HDA) crystallizable side chains for high latent heat and allyloxy poly(ethylene glycol) (APEG) for enhanced flexibility. Electrospinning followed by ultraviolet (UV) irradiation induces nitrile‐group radical reactions, generating covalently bonded cyclic and ladder‐like domains. This UV‐driven crosslinking builds a robust 3D network that stabilizes side‐chain crystallization, prevents leakage, and sustains structural integrity during repeated transitions. The aerogels exhibit ultralow density (12.29 mg/cm 3 ), high porosity (99.02%), and low thermal conductivity (0.025 W m −1 K −1 ), along with a 5.6‐fold increase in compressive strength and ∼88% stress retention after 300 cycles. Latent heat remains 98.4% after 100 cycles. In practical tests, the aerogel maintains only a 2.2°C surface increase on a 60°C plate for 1200 s and cools by just 1.0°C after removal, confirming excellent insulation and heat‐storage capability. This work offers an effective strategy for solid–solid phase‐change aerogels toward advanced thermal regulation and sustainable energy use.