Fluorine-free strongly dipolar polymers exhibit tunable ferroelectricity.

Area of Science:

• Polymer Science
• Materials Chemistry
• Organic Electronics

Background:

• Current ferroelectric polymers, primarily poly(vinylidene fluoride) (PVDF)-based fluoropolymers, exhibit excellent performance but raise environmental concerns due to their persistent nature ('forever chemicals').
• There is a significant need for environmentally benign alternatives to traditional fluoropolymers in ferroelectric applications.

Purpose of the Study:

• To design and synthesize a novel family of fluorine-free ferroelectric polymers.
• To investigate the structure-property relationships governing ferroelectric behavior in these new materials.
• To evaluate their potential as alternatives to existing fluoropolymer-based ferroelectrics.

Main Methods:

• Rational molecular design incorporating a polyoxypropylene main chain and disulfonyl alkyl side chains.
• Experimental characterization of synthesized polymers.
• Computational simulations to understand ferroelectric ordering mechanisms.
• Performance evaluation of electroactuation and electrocaloric effects.

Main Results:

• A new class of fluorine-free ferroelectric polymers based on polyoxypropylene with disulfonyl side chains was successfully synthesized.
• Ferroelectric ordering was induced by strong dipole-dipole interactions between neighboring disulfonyl groups.
• Tunable ferroelectric properties were achieved by modifying the side chain (R group): ferroelectric for R = -H and relaxor ferroelectric for R = -CH₃.
• The relaxor polymer demonstrated electroactuation and electrocaloric performance competitive with state-of-the-art PVDF-based tetrapolymers at low electric fields.

Conclusions:

• The developed fluorine-free polymers represent a promising, environmentally conscious alternative to conventional ferroelectric fluoropolymers.
• The strong dipole-dipole interactions in the disulfonyl groups are key to achieving ferroelectricity.
• These novel materials show potential for applications requiring electroactive and electrocaloric responses, such as sensors and energy harvesting devices.