Cyclic Macroscopic Assembly and Disassembly Driven by Ionic Strength Fuel: A Waste-Free Approach

Nonequilibrium assembling systems developed so far havereliedon chemical fuels to drive the programmable pH cycles, redox reactions,and metastable bond formations. However, these methods often resultin the unwanted accumulation of chemical waste. Herein, we presenta novel strategy for achieving cyclic and waste-free nonequilibriumassembly and disassembly of macroscopic hydrogels, utilizing an ionicstrength-mediated approach. Our strategy involves using ammonium carbonateas a chemical fuel to temporally regulate the attractions betweenoppositely charged hydrogels via ionic strength-controlled chargescreening and hydrogel elasticity changes. This chemical fuel effectivelymediates the assembly/disassembly processes and prevents waste accumulation,as ammonium carbonate can completely decompose into volatile chemicalwaste. The cyclic and reversible assembly process can be achievedwithout significant damping due to the self-clearance mechanism, aslong as the chemical fuel is repeatedly supplied. This concept holdspromise for creating macroscopic and microscopic nonequilibrium systemsand self-adaptive materials.

Automated summary

This study presents a novel strategy for achieving cyclic and waste-free nonequilibrium assembly and disassembly of macroscopic hydrogels, utilizing an ionic strength-mediated approach. The strategy involves using ammonium carbonate as a chemical fuel to temporally regulate the attractions between oppositely charged hydrogels. This concept holds promise for creating macroscopic and microscopic nonequilibrium systems and self-adaptive materials.