Professor James Grunlan’s group at Texas A&M University (College Station, Texas) termed it as an intumescent all-polymer multilayer nanocoating. The work is important because a) the nanocoating did not have any inorganic composent (such as halogens, Al, Mg etc.) as is the case for most of the fire retardant system; b) intumescent coatings have not been utilized on fabric before; c) nanocoating was deposited layer-by-layer on cotton fabric and thus coating thickness could be controlled as necessary; and d) this developmental work could be extended to many other systems.
Authors reported that fire is extinguished right after ignition on the fabric during vertical flame testing. How the coatings extinguish fire – by intumescent effect.
Why the nanocoating is called intumescent?
Intumescent materials are those which swell when exposed to high heat, increasing its volume while decreasing the density. Intumescent coatings char and could expand up to several times (even to 100 times depending on the systems) their original thickness when exposed to heat or flame. Essentially, the char insulates the surface and limits oxygen supply to prevent combustion. Can this intumescent polymer nanocoating be used in other products so as to avoid the potentially toxic flame retardants those are still in use? The future research will tell!
The current intumescent polymer nanocoating as reported are not without its limitations: 1) the coated fabric becomes stiffer and 2) its durability is unknown. Further research is under way to address these issues.
[Reference: Y-C. Li; S. Mannen, A.B. Morgan, SC. Chang, Y-H. Yang, B. Condon, and J.C. Grunlan; Advanced Materials, DOI: 10.1002/adma.201101871]
