Revitalizing Inert Materials: Grafting Self‐Oscillating, Stimuli‐Responsive Organometallic Polymers for Pulsating Systems

Abstract

Abstract A major challenge in materials science is dynamically adjusting material properties using sensors and control systems. This contribution develops a new approach using a self‐oscillating copolymer to autonomously change material surface properties in response to environmental changes. A redox‐sensitive terpolymer of N‐isopropylacrylamide (NIPAM), dimethylacrylamide (DMAc), and an iron‐based comonomer ([(phen)2(phen‐5‐yl‐acrylamide)FeII](PF6)2) is synthesized via Reversible Addition‐Fragmentation Chain Transfer (RAFT) polymerization, catalyzing an oscillating redox reaction (Belousov‐Zhabotinsky, BZ). The terpolymer oscillates from soluble to insoluble around 35 °C based on the iron's oxidation state. A catechol unit is incorporated to enhance versatility, enabling grafting onto different surfaces. Optimal BZ reagent concentrations are explored for maximum oscillation amplitude and frequency. By selecting a working temperature between redox transition points, the copolymer's oscillation from coil to globular conformation is observed due to redox oscillations. The self‐oscillating copolymer is grafted onto an ultrafiltration membrane, where conformational changes cause variations in pore size, leading to rapid negative flux peaks that disrupt the flux and reduce membrane fouling during protein filtration. This study highlights self‐oscillating polymers' ability to impart dynamic properties to inert materials, paving the way for smart materials with self‐regulating properties to adapt to changing conditions.

Keywords

• Belousov‐Zhabotinsky oscillator
• membrane
• self‐oscillating polymer
• stimuli‐responsive polymer