Designing Next Generation Polymer-Based Surfactants for Fire Suppression
Abstract
Current aqueous film-forming foams (AFFFs) employed for liquid fuel fire suppression by the military utilize perfluorinated compounds (PFCs) as surfactants. PFCs exhibit toxicity, bioaccumulation, and persistence in the environment, resulting in fluoro-containing surfactants in regions not directly exposed to PFCs but rather through secondary exposure by chemical migration. While fluorinated compounds provide desirable thermo-oxidative stability and excellent fire retardancy, the environmental impact imposed by these chemicals spurs research that targets the complete removal of PFCs in conventional surfactant formulations. In view of this, the design and synthesis of a series of wholly aromatic polyimides aims to replace PFCs in liquid fuel fire suppression (Scheme 1). The synthesized polyimides comprise highly thermally stable moieties that provide excellent fire resistance, high char yields, and highly rigid polymer backbones, yielding infusible materials. Likewise, the incorporation of metal-substituted sulfonate pendent groups enables water solubility for the rigid-rod polymers. Tailoring of the polyimide backbone through copolymerization with sulfonated and non-sulfonated monomers permits a family of polyimides to exhibit a balance of water solubility and flame suppression. When combined with non-toxic surfactants and salts in water, these sulfonated polyimides (sPI) have a high propensity for stable foam formation. The MIL-F-24385F performance requirement evaluates foam quality/stability, drainage time, and burn-back resistance to access viability and provides a comparison to other systems. To remove small molecule additives, sPI foam systems with backbone-tethered ammonium and phosphonium ion surfactants are also investigated. Overall, the investigated systems performed well as stand-ins to AFFF but will require further development and optimization to realize a commercially accessible product.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2021
- Accession Number
- AD1154592
Entities
People
- Benjamin J. Stovall
- Brian Lattimer
- Clay B. Arrington
- Gerard G. Back
- Joshua B. Dinaburg
- Timothy E. Long
Organizations
- Virginia Tech