Solid-Liquid Europium Ion Extraction via Phosphonic Acid-Functionalized Polyvinylidene Fluoride Siloxanes

Area of Science:

• Materials Science
• Polymer Chemistry
• Environmental Chemistry

Background:

• Developing efficient materials for rare-earth element extraction is crucial for resource recovery and environmental remediation.
• Vinylidene fluoride (VDF)-based polymers offer unique properties but require functionalization for specific applications like ion binding.

Purpose of the Study:

• To synthesize novel terpolymers incorporating vinylidene fluoride (VDF), vinyltriethoxysilane (VTEOS), and vinyldimethylphosphonate (VDMP).
• To investigate the crosslinking behavior and thermal properties of the resulting terpolymers.
• To evaluate the efficacy of these functional terpolymers in extracting europium (Eu(III)) ions from aqueous solutions.

Main Methods:

• Radical terpolymerization of VDF, VTEOS, and VDMP to yield poly(VDF-ter-VDMP-ter-VTEOS) terpolymers.
• Characterization using NMR (¹H, ¹⁹F, ²⁹Si, ³¹P) spectroscopy.
• Crosslinking via sol-gel process of triethoxysilane groups in acidic media.
• Analysis of crosslinked networks using solid-state NMR, TGA, and DSC.
• Hydrolysis of dimethyl phosphonate groups to phosphonic acid.
• Europium ion extraction experiments.

Main Results:

• Successful synthesis of poly(VDF-ter-VDMP-ter-VTEOS) terpolymers with controlled compositions (70-90% VDF, 5-20% VTEOS, 10% VDMP) in 50-80% yields.
• Crosslinking via sol-gel process created a 3D network, increasing crystallinity from 9.7% to 12.1%.
• Terpolymers exhibited moderate thermal stability up to 300 °C.
• Hydrolyzed terpolymers demonstrated very high removal capacity for Eu(III) ions, achieving total removal at low concentrations.

Conclusions:

• Novel functional terpolymers based on VDF, VTEOS, and VDMP were successfully synthesized and crosslinked.
• The crosslinked terpolymers possess favorable thermal stability and enhanced crystallinity.
• These materials show exceptional potential for the efficient extraction of europium ions from water, addressing environmental and resource recovery needs.