Ice-Template Crosslinked PVA Aerogels Modified with Tannic Acid and Sodium Alginate

Area of Science:

• Materials Science
• Polymer Science
• Green Chemistry

Background:

• Conventional foam materials often have significant environmental impacts.
• There is a growing need for sustainable alternatives with comparable performance.
• Bio-based and biodegradable aerogels offer a promising avenue for greener material solutions.

Purpose of the Study:

• To enhance the properties of poly(vinyl alcohol) (PVA) aerogels.
• To improve mechanical strength, thermal insulation, and flame retardancy.
• To explore the use of sodium alginate (SA) and tannic acid (TA) as additives.

Main Methods:

• PVA aerogels were synthesized using freeze-drying.
• Sodium alginate and tannic acid were incorporated into the PVA matrix.
• Post-ion crosslinking was performed using calcium chloride and boric acid solutions.
• Mechanical, thermal, and flame retardancy properties were evaluated.

Main Results:

• Incorporation of TA and SA significantly increased the compressive specific moduli of PVA aerogels (up to six-fold).
• PVA/TA/SA aerogels exhibited low thermal conductivity (0.043-0.046 W/m·K).
• Crosslinking enhanced thermal stability, reducing degradation rates by seven-fold.
• Flame retardancy was improved, with significant reductions in heat release rate and fire growth index.

Conclusions:

• The combination of PVA, SA, and TA creates robust, thermally stable, and flame-retardant aerogels.
• Ion crosslinking further boosts the material's performance, particularly in thermal stability and fire resistance.
• These bio-based aerogels represent a sustainable alternative to conventional foams.