pH regulation of 1,2-bis(trimethoxysilyl)ethane hydrolysis pathways for enhanced wet state stability of TEMPO-oxidized cellulose nanofiber aerogels.

2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofiber (TOCNF) aerogels suffer from poor wet-state structural stability, limiting their applications in aqueous environments. Herein, a pH-regulated silane crosslinking strategy using 1,2-bis(trimethoxysilyl)ethane (BTMSE) was developed to fabricate wet-state mechanically durable and water-stable TOCNF aerogels. To avoid acid-induced aggregation of TOCNF suspensions, BTMSE was pre-hydrolyzed under different pH conditions before mixing with TOCNF dispersions. The pre-hydrolysis pH regulated the competition between cellulose-silane interactions and silanol self-condensation, generating distinct network architectures. Weakly acidic conditions promoted the formation of a homogeneous interfacial crosslinked network, whereas neutral conditions promoted more extensive siloxane condensation and Si-O-Si-rich structures. Consequently, the aerogels exhibited tunable wet-state mechanical responses and structural durability. The aerogels possessed aligned porous structures, low densities (10.6-20.4 mg cm-3), high porosities (>98%), superhydrophilicity, rapid water-transport capability, and enhanced resistance to water immersion and ultrasonication. Unlike hydrophobic reinforcement strategies, this approach preserved the intrinsic hydrophilicity of TOCNF networks while significantly improving wet-state structural durability. The optimized pH 4 aerogel retained 88.8% and 100.6% of its compressive stress after ultrasonication and 7-day water immersion, respectively. In addition, the aerogels demonstrated stable underwater piezoresistive sensing performance. This work provides an effective strategy for engineering hydrophilic yet wet-state mechanically resilient nanocellulose aerogels for water-related applications.