Thermo-Electro-Responsive Redox-Copolymers for Amplified Solvation, Morphological Control, and Tunable Ion...

Area of Science:

• Materials Science
• Polymer Chemistry
• Electrochemistry

Background:

• Electro-responsive metallopolymers are promising for ion-selective separations.
• Limited understanding exists regarding solvation and polymer-solvent interactions in ion binding.
• Elucidating these interactions is key to designing advanced ion-selective materials.

Purpose of the Study:

• To investigate the role of solvation and polymer-solvent interactions in ion selectivity.
• To develop tunable thermo-electrochemical-responsive copolymer electrodes.
• To explore macromolecular engineering strategies for modulating ion selectivity.

Main Methods:

• Synthesis of N-isopropylacrylamide (NIPAM) and ferrocenylpropyl methacrylamide (FPMAm) copolymers.
• Electrochemical quartz crystal microbalance to measure water uptake.
• Spectroscopic ellipsometry to determine swelling/deswelling behavior.
• Neutron reflectometry to analyze depth profiles and solvation.

Main Results:

• The P(NIPAM0.9-co-FPMAm0.1) copolymer showed a significant increase in water uptake upon oxidation compared to PFPMAm.
• This copolymer exhibited thermo-electrochemically reversible swelling (up to 83%) and deswelling.
• Neutron reflectometry revealed distinct solvation profiles between reduced and oxidized states.
• A fivefold difference in ion selectivity was observed, linked to polymer hydrophilicity.

Conclusions:

• Polymer hydrophilicity is a critical factor in ion partitioning and selectivity.
• Tunable polymer-solvent interactions offer new pathways for designing stimuli-responsive ion-selective materials.
• Macromolecular engineering of copolymers can effectively modulate ion selectivity.