Rapid photocrosslinking strategy for fabricating monolithic aerogels from surface-modified boehmite nanofibers

Monolithic porous materials derived from hydrolysis–condensation processes typically undergo time-dependent gelation governed by intrinsic reaction kinetics. Once the reaction is initiated, structural consolidation proceeds spontaneously, making rapid and programmable immobilization of a percolated framework difficult. This study reports a photoresponsive gelation strategy for boehmite nanofiber (BNF)-based monolithic aerogels. Photopolymerizable functional groups were introduced onto nanofiber surfaces using 3-(methacryloyloxy)propyltrimethoxysilane (MPTMS), followed by covalent interfiber crosslinking through photoinduced radical polymerization. The modified BNF dispersions remained stable over extended periods in the presence of a photoinitiator but underwent gelation and network fixation within tens of seconds upon ultraviolet irradiation under ambient conditions. This externally activated process enabled rapid immobilization of a percolated inorganic nanofiber framework. The resulting aerogels exhibited bulk densities of 0.093–0.37 g cm − 3 and specific surface areas of 328–429 m 2 g − 1 . Their compressive modulus increased proportionally with increasing MPTMS content. At the optimal composition, the thermal conductivity was 0.0228 W m − 1 K − 1 at 20 °C, which is lower than that of air under the same conditions. The monoliths retained their structural integrity after heat treatment at 150 °C for 6 h. The photocrosslinking strategy enables rapid fixation of a percolated nanofiber network while preserving the highly open fibrous pore architecture characteristic of low-density aerogels. This approach provides a practical route for controlling gelation timing and supports the fabrication of shape-controlled thermally insulating monolithic aerogels.