Poly(vinylidene fluoride) Aerogels with α, β, and γ Crystalline Forms: Correlating Physicochemical Properties with...

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Crystalline forms of poly(vinylidene fluoride) (PVDF) aerogels are crucial for applications like energy harvesting and insulation.
• Controlling the crystalline structure of PVDF aerogels is essential for tailoring their properties.

Purpose of the Study:

• To develop sustainable strategies for preparing pure α, β, and γ crystalline forms of PVDF aerogels.
• To investigate the influence of different solvents on PVDF gelation and resulting aerogel crystalline structures.
• To explore the structure-property relationships of PVDF aerogels with distinct crystalline polymorphs.

Main Methods:

• Utilized a solvent exchange strategy with green solvents followed by freeze-drying to prepare PVDF aerogels.
• Employed crystallization-induced gelation by carefully selecting polymer-solvent interactions.
• Synthesized specific crystalline forms (α, β, γ) using cyclohexanone, γ-butyrolactone, or a dimethylacetamide/water mixture.

Main Results:

• Successfully prepared crystalline pure α, β, and γ forms of PVDF aerogels.
• Demonstrated that solvent choice modulates PVDF chain conformation and crystalline structure.
• Observed distinct morphologies, mechanical properties, hydrophobicities, acoustic, and electrical properties for each crystalline form.
• Measured exceptionally low thermal conductivity (∼0.040 ± 0.003 W m⁻¹ K⁻¹) across all PVDF aerogel types.

Conclusions:

• Developed a versatile and sustainable approach for fabricating PVDF aerogels with controlled crystalline structures.
• Highlighted the potential of these tailored PVDF aerogels for multifunctional applications due to their varied physicochemical properties.
• Confirmed the consistent low thermal conductivity of PVDF aerogels, regardless of their crystalline polymorph.