Engineering Sulfur‐Containing Polymeric Fire‐Retardant Coatings for Fire‐Safe Rigid Polyurethane Foam

• Published in: Macromolecular rapid communications. Vol. 45; no. 14; pp. e2400068 - n/a
• Main Authors: Fang, Yang, Ma, Zhewen, Wei, Dewang, Yu, Youming, Liu, Lei, Shi, Yongqian, Gao, Jiefeng, Tang, Long‐Cheng, Huang, Guobo, Song, Pingan
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.07.2024
• Subjects: Adhesion; Adhesive bonding; Adhesive strength; Bonding strength; Coatings; Copolymerization; Copolymers; Design optimization; Energy conservation; Fire protection; fire retardant; Fire safety; fire‐retardant coatings; Flammability; Foams; Heat release rate; Heat transfer; Hydroxyethyl acrylate; Physical properties; Plastic foam; Plastic foams; Polymer coatings; Polyurethane; Polyurethane foam; Reagents; Sodium; Styrene; Sulfonic acid; Sulfur; sulfur‐containing polymers; Synthesis; Thermal conductivity; Thermal insulation; polyurethane foam; sulfur‐containing polymers; fire‐retardant coatings; fire retardant
• ISSN: 1022-1336; 1521-3927; 1521-3927
• DOI: 10.1002/marc.202400068

With the advantages of lightweight and low thermal conductivity properties, polymeric foams are widely employed as thermal insulation materials for energy‐saving buildings but suffer from inherent flammability. Flame‐retardant coatings hold great promise for improving the fire safety of these foams without deteriorating the mechanical‐physical properties of the foam. In this work, four kinds of sulfur‐based flame‐retardant copolymers are synthesized via a facile radical copolymerization. The sulfur‐containing monomers serve as flame‐retardant agents including vinyl sulfonic acid sodium (SPS), ethylene sulfonic acid sodium (VS), and sodium p‐styrene sulfonate (VSS). Additionally, 2‐hydroxyethyl acrylate (HEA) and 4‐hydroxybutyl acrylate are employed to enable a strong interface adhesion with polymeric foams through interfacial H‐bonding. By using as‐synthesized waterborne flame‐retardant polymeric coating with a thickness of 600 µm, the coated polyurethane foam (PUF) can achieve a desired V‐0 rating during the vertical burning test with a high limiting oxygen index (LOI) of >31.5 vol%. By comparing these sulfur‐containing polymeric fire‐retardant coatings, poly(VS‐co‐HEA) coated PUF demonstrates the best interface adhesion capability and flame‐retardant performance, with the lowest peak heat release rate of 166 kW m−2 and the highest LOI of 36.4 vol%. This work provides new avenues for the design and performance optimization of advanced fire‐retardant polymeric coatings. Four sulfur‐containing fire‐retardant copolymers are synthesized via a one‐step radical copolymerization, and their thermal stability, flame‐retardant, and smoke‐suppression properties are assessed for potential applications as fire‐retardant coatings for rigid polyurethane foam.