A green synthesis strategy for liquid microcapsule flame-retardant polyurethane foam: Lowering consumer health risks from flame retardant inhalation and ensuring long-lasting fire safety

Abstract

Dimethyl methylphosphonate (DMMP), is widely used in the production of commercial flexible polyurethane foam due to its excellent fire-retardant properties and the low addition levels required. However, in daily use, the volatility and migration of this liquid fire retardant reduce its fire safety performance and pose significant health risks. To address this issue, we employed interfacial polymerization facilitated by ultraviolet light-induced triallyl isocyanurate (TAIC) cross-linking at the water-oil interface to rapidly encapsulate DMMP. Incorporating TAIC@DMMP microcapsules into FPUF composites effectively suppressed DMMP emissions, maintaining low health and fire safety risks. These microcapsules act as sprinkler heads within each FPUF cell, rupturing during flame propagation. This release of phosphorus-containing radicals significantly enhances fire safety, reducing the peak heat release rate (PHRR) and total heat release (THR) by approximately 47% and 33%, respectively. The TAIC@DMMP microcapsule FPUF composite material exhibited excellent fire safety performance after 28 years of long-term aging simulated in an oven, passing the vertical burning test. In an environment simulating a 60 °C heat source, the TAIC@DMMP microcapsule FPUF composite material significantly reduced the release of DMMP, lowering the carcinogenic risk and non-carcinogenic risk by approximately 80 times and 100 times, respectively. This study presents a method for preparing FPUF composites that balance fire safety and environmental health, offering a valuable reference for further research on flame-retardant materials in environmental safety.