Fabrication of dimethyl methylphosphonate-loaded mesoporous silica nano fire extinguisher and flame retarding unsaturated polyester

A novel nano fire extinguisher is constructed by loading the guest molecule (dimethyl methylphosphonate, DMMP) into the host material (mesoporous silica, m-SiO 2 ) by a vacuum-assisted immersion method. SiO 2 -DMMP can avoid the excessive plasticization caused by the high addition of DMMP; under a relatively high addition amount (20 phr), the unsaturated polyester (UP) can normally be cured. 20 phr SiO 2 -DMMP imparts excellent flame retardancy to UP, i.e., 49.8% reduction in peak heat release rate and passing the UL-94 V-0 rating. Moreover, through the mesoporous confinement of m-SiO 2 , the thermal stability of DMMP is improved. In addition, easy migration of DMMP in UP is also solved; the UP can pass the UL-94 V-0 rating after soaking in water for 72 h. The flame retardant mechanism is the quenching mechanism. This strategy will be a universal method for loading liquid flame retardants to construct SiO 2 -based composite flame retardants. • Mesoporous silica-loaded dimethyl methylphosphonate was prepared for the first time. • The mesoporous confinement of m-SiO 2 can improve the thermal stability of DMMP. • Problems of easy migration and over-plasticization of DMMP in UP were also solved. • The SiO 2 -DMMP exhibited excellent flame retardancy in UP as a nano-fire extinguisher. • The flame-retardant mechanism is mainly the quenching mechanism in the gas phase.