To successfully prepare cellulose hydrogels through a dissolution–regeneration process, 60 wt% LiBr aqueous solution was used as a green solvent. Carboxyl groups were precisely introduced onto the surface of the cellulose hydrogels through a TEMPO-mediated oxidation reaction, while the three-dimensional network structure and open pore morphology were completely retained. This modification strategy significantly enhanced the loading capacity of the hydrogels with copper nanoparticles (Cu NPs). The experimental results show that the LiBr aqueous solution can efficiently dissolve cellulose, and the TEMPO oxidation introduces carboxyl groups without destroying the stability of the hydrogels. Cu NPs are uniformly dispersed and highly loaded on the surface of the hydrogel because of the anchoring effect of the carboxyl groups. Cu NP-loaded hydrogels exhibit excellent catalytic activity in the NaBH₄ reduction of 4-nitrophenol (4-NP). Cu NP-loaded hydrogels maintain their complete structure and good catalytic performance after five consecutive cycles. Moreover, Cu NP-loaded hydrogels demonstrate high efficiency in degrading organic dyes such as methyl orange and Congo red. This study successfully developed efficient, low-cost, and environmentally friendly Cu NP-loaded hydrogel catalysts through the synergistic effect of LiBr green solvent and TEMPO oxidation modification, providing a feasible alternative to noble metal catalysts.

Ultrasound is conventionally applied to modify starch in its native or gelatinized states; however, its dynamic impact during active gelatinization remains largely unexplored. This study investigated the effects of thermo-ultrasound intervention at critical phase-transition temperatures (60, 69, and 73 °C) of corn starch. The results indicate that the intervention temperature functions as a definitive thermodynamic switch modulating the structural and rheological properties of the starch. Mild intervention (60 °C) promoted a porous structural activation and crystalline annealing, resulting in significantly enhanced gel viscosity and swelling power. At the intermediate state (69 °C), granules achieved maximal volumetric expansion but exhibited pronounced mechanical vulnerability under continuous shear. Conversely, intervention at the elevated temperature (73 °C) led to extensive microstructural collapse and a marked reduction in viscosity. Further spectroscopic and rheological analyses elucidated the molecular mechanisms driving these divergent results. Dynamic spectral mapping revealed a fundamental kinetic reversal in the phase transition: a shift from an "Outside-In" hydration-led sequence at 60 °C to an "Inside-Out" fragmentation-led disassembly at 73 °C. Ultimately, this study demonstrates that targeting specific thermodynamic windows during gelatinization provides a highly programmable strategy for tailoring starch functionality.