Chemomechanical Motion of a Self‐Oscillating Gel in a Protic Ionic Liquid

Abstract

An autonomous swelling–deswelling oscillation of polymer gels in a hydrated protic ionic liquid (PIL) as a proton source for the Belousov–Zhabotinsky (BZ) reaction is presented. Methylammonium hydrogen sulfate ([maH+][HSO4−]) was employed as the PIL because it provides stable redox oscillation in the BZ reaction. Due to the significantly higher pKa for [maH+][HSO4−] than those for conventional proton sources for the BZ reaction, chemomechanical oscillation can be expected under weaker acidic conditions. The self‐oscillating polymer was designed as a ternary random copolymer of N‐isopropylacrylamide, N‐(3‐aminopropyl)methacrylamide, and the Ru(bpy)3 moiety as a catalyst for the BZ reaction. The copolymer exhibited spontaneous soluble–insoluble oscillation in hydrated [maH+][HSO4−] containing NaBrO3 and malonic acid. Macroscopic swelling–deswelling oscillation of the porous bulk gel prepared by covalently connecting microgel particles was also observed.

Extraction of mechanical work from stimuli-responsive molecular systems and materials

“…For instance, the redox-responsive catalyst of the BZ reaction can be covalently incorporated inside PNIPAM-based hydrogels. The oscillating change in hydrophilicity of the catalyst result in an oscillating modulation of the hydration equilibrium of the polymer, thereby leading to an oscillating volume change of the material (Figure 2A) [34,35]. An oil pump was recently reported with this type of material [36].…”

“…Importantly, the potential difference averages to zero over time. (A-C) adapted, with permission, from [35,39,42], respectively. fluoride) (PVDF) films [42].…”

Strong Cationic Radical Initiator‐Based Design of a Thermoresponsive Hydrogel Showing Drastic Volume Transition

“…[1][2][3][4][5][6] In the past few decades, various gel functions, including stimuli response, self-oscillation, self-healing, high mechanical strength, and biomolecular recognition, have been developed. [7][8][9][10][11][12][13] Moreover, researchers have attempted strategic control of the gel structure, [14][15][16][17][18] because the molecular design of polymer networks plays a significant role in the development of various gel functionalities. www.advancedsciencenews.com www.mcp-journal.de…”

Growing Polymer Vesicles Generated by Polymerization Induced Self-Assembly Coupled With a Living Chemical Reactor

“…And due to its stable, long-lasting, and repeatable oscillation features, BZ reaction has also been employed in the development of chemical tuning machine and chemical analog of noisy “metabolism” system, to handle information ( Srivastava et al, 2018 ). The combination of BZ reaction with soft matters or polymeric systems has also led to numerous applications, such as the generation of self-beating or self-oscillating gels, colloidosomes, vesicles, and polymer brushes as well as chemomechanical coupling systems ( Pereira de Souza and Perez-Mercader, 2014 ; Tamate et al, 2014 , 2016 ; Masuda et al, 2015 , 2016 , 2018 ; Ren and Perez-Mercader, 2018 ; Onoda et al, 2017 ; Hu and Pérez-Mercader, 2018 ).…”