Independent network in between cotton fibers.
Cost effective: Empa scientist Sabyasachi Gaan uses steam from a business pressure cooker to flame slow down samples of cotton fabric. Credit: Empa.
A new chemical process developed by Empa turns cotton into a fireproof fabric, that nonetheless retains the skin-friendly residential or commercial properties of cotton.
The unique phosphorus chemistry can also be used to establish other products, e.g. to make hydrogels that can launch drugs upon modifications in pH. Such gels could find application in treating wounds that heal slowly. In such wounds, the pH of the skin surface increases and the new phosphorus-based gels can be activated to launch medication or a color that alerts nurses and medical professionals to the issue. Empa has also patented the production of such hydrogels.
Reference: “In-situ phosphine oxide physical networks: A facile technique to accomplish resilient flame retardant and antimicrobial treatments of cellulose” by Rashid Nazir, Dambarudhar Parida, Joel Borgstädt, Sandro Lehner, Milijana Jovic, Daniel Rentsch, Ezgi Bülbül, Anja Huch, Stefanie Altenried, QunRen, Patrick Rupper, Simon Annaheim and Sabyasachi Gaan, 9 December 2020, Chemical Engineering Journal.DOI: 10.1016/ j.cej.2020.128028.
Sturdiness vs. toxicity.
A modern solution from the pressure cooker.
” Until now, it has actually constantly taken a compromise to make cotton fire-resistant,” says Sabyasachi Gaan, a chemist and polymer specialist who works at Empas Advanced Fibers lab. Wash-durable flame retardant cotton in industry is produced by treating the fabric with flame retardants, which chemically links to the cellulose in the cotton.
Gaan understands the chemistry of cotton fibers well and has spent many years at Empa developing flame retardants based upon phosphorus chemistry that are currently used in lots of commercial applications. Now he has actually been successful in finding a simple and elegant way to anchor phosphorous in kind of an independent network inside the cotton.
Gaan and his coworkers Rashid Nazir, Dambarudhar Parida and Joel Borgstädt utilized a tri-functional phosphorous substance (trivinylphosphine oxide), which has the ability of reacting just with particularly included molecules (nitrogen substances like piperazin) to form its own network inside cotton. This makes the cotton completely fire-resistant without blocking the favorable -OH groups. In addition, the physical phosphine oxide network also likes water. This flame retardant treatment does not consist of carcinogenic formaldehyde, which would endanger textile workers throughout textile production. The phosphine oxide networks, hence formed, does not wash out: After 50 launderings, 95 percent of the flame retardant network is still present in the fabric.
To render extra protective functionalities to the flame retardant cotton developed at Empa, the scientists likewise integrated in situ created silver nanoparticles inside the fabric. This works well in a one-step procedure together with generating the phosphine oxide networks. Silver nanoparticles provide the fiber with antimicrobial homes and endure 50 laundry cycles, too.
State-of-the-art flame retardant cotton fabrics suffer from release of formaldehyde and are uncomfortable to wear.” Until now, it has always taken a compromise to make cotton fireproof,” says Sabyasachi Gaan, a chemist and polymer expert who works at Empas Advanced Fibers lab. Wash-durable flame retardant cotton in industry is produced by treating the fabric with flame retardants, which chemically links to the cellulose in the cotton. While formaldehyde-based flame retardant treatments are durable, they have extra disadvantages: The -OH groups of cellulose are chemically obstructed, which considerably reduces the ability of cotton to soak up water, which results in an uncomfortable fabric.
To render additional protective performances to the flame retardant cotton established at Empa, the researchers also integrated in situ generated silver nanoparticles inside the fabric.
“Steaming fabrics after coloring, printing and ending up is a normal step in textile industry. It does not require an extra investment to apply our process,” mentions the Empa chemist.
On the other hand, this freshly developed phosphorus chemistry and its application is secured by a patent application. “Two important hurdles remain,” Gaan states. “For future commercialization we require to find a suitable chemical producer who can produce and supply trivinylphosphine oxide. In addition, trivinylphosphine oxide needs to be REACH-registered in Europe.”.
By Swiss Federal Laboratories for Materials Science and Innovation (EMPA).
September 18, 2021.
Cutting edge flame retardant cotton textiles suffer from release of formaldehyde and are unpleasant to use. Cotton is skin-friendly because it can soak up significant quantities of water and maintain a favorable microclimate on the skin.
For such purposes, cotton is generally used as an inner fabric layer that needs extra homes: For example, it needs to be fire-resistant or safeguard against biological contaminants. These additional properties can be developed into the cotton fibers by ideal chemical modifications.
A gel that releases drugs.
