Ultralight and Mechanically Robust Fibrous Sponges Tailored by Semi-Interpenetrating Polymer Networks for Warmth Retention.

People living in very cold climates urgently desire warmth retention equipment to remain healthy. However, creating materials that exhibit both effective warm retention and robust mechanical properties to maintain stable structures is extremely challenging. Herein, we report a facile and time-saving strategy for preparing ultralight, mechanically robust, and high-performance warmth retention materials via direct electrospinning and thermal crosslinking. Fluffy fibrous assemblies with stereoscopic fiber networks are fabricated with a humidity-induced electrospinning technique, followed by heating to create semi-interpenetrating polymer networks (semi-IPNs) within fibers to acquire fibrous sponges (FSs). The semi-IPN-based FSs (semi-IPN FSs) present integrated properties of high tensile stress (∼1 MPa), good fatigue resistance (∼0% plastic deformation after 1000 cyclic tensile or compressive tests), and nondestructive resilience in liquid nitrogen (-196 °C). Furthermore, the semi-IPN FSs exhibit a low volume density of ∼2.2 mg cm-3, effective heat preservation ability (low thermal conductivity ∼25.8 mW m-1 K-1), and desired waterproofness and breathability. The successful synthesis of semi-IPN FSs provides a novel attempt to develop high-performance materials with robust mechanical properties for numerous applications.