A group of researchers has successfully produced a structurally strong and highly fire-protecting polyimide/MXene hybrid aerogel with accurate thermal detection and flame warning capacity using a PI@MXene composite, according to a recent study published in the Chemical Engineering Journal.
Study: Mechanically robust and multifunctional polyimide/MXene composite aerogel for smart fire protection. Image Credit: prapann/Shutterstock.com
The development of multipurpose, sophisticated fire-protection aerogels is urgently required to keep up with the demands of the new technological age.
What are Polyimide (PI) Aerogels?
As a result of their extremely low concentration, high permeability, exceptional thermal insulation, and high durability, natural aerogels such as polymeric aerogel and fibrous aerogel have been commonly used in several applications, including external wall insulation, oil/water isolation, and fuel extraction. However, most organic aerogels have poor thermal stability and inadequate fire protection.
Nevertheless, owing to its special aromatic compound, polyimide (PI) aerogel has excellent thermal stability, mechanical properties, and heat resistance, making it a promising candidate for use in aircraft, high-speed railways, and sophisticated robotics.
In recent years, greater emphasis has been placed on improving the fire prevention and versatility of the PI aerogel to meet rising demands in a variety of circumstances. One of the most successful techniques to enhance the fire prevention of aerogels is to equip them with a precise fire-warning capability.
Limitations of Previously Used Fire-Warning Sensors
Because of its rapid thermal decrease at high temperatures, graphene oxide (GO) has been employed to make fire-warning detectors.
Despite making tremendous improvements, it is still far from satisfactory for several reasons.
To begin with, owing to the permanent reducing processes of GO at high temperatures, GO-based sensors are unable to monitor fire rebirth.
Second, the fire-warning mechanism cannot be activated until a noticeable electrical resistance shift in the connection is observed, which necessitates a sufficiently large burning region.
Third, to create an electronic current, GO-based sensors need an external source of power, which adds to the system's complexity and unreliability.
The creation of thermoelectric (TE) materials was hailed as a game-changing breakthrough in the fabrication of sophisticated fire-safe aerogels.
The Seebeck ability causes the TE materials to directly transform heat into volts and work without an external energy source. However, the leaking of ionic liquids substantially restricts the use of TE nanomaterials in fire-warning devices.
MXene: A Novel Flame Retardant Material
Because of its strong mechanical characteristics, photonic qualities, and high electrical conductance, MXene has sparked a lot of attention as a novel two-dimensional substance.
MXene also exhibits high water distribution because of the abundance of polar endpoints on its interface and highly specific surface regions.
Due to its strong thermodynamic characteristics, high conductance, and heat resistance, MXene is considered one of the finest choices for manufacturing multipurpose fire-retardant PI aerogel with thermal sensing and fire-warning properties.
Previously, applying an MXene nanosheet resulted in multipurpose smart fireproof cotton fibers with a responsive fire-warning system.
It continuously activated the fire-warning device without an external energy source while being torched in less than 10s. However, no multipurpose fire-warning aerogel dependent on the piezoelectric effect has been recorded.
This challenge was solved in this study, as the researchers used a dip-coating approach to produce a structurally resilient and versatile polyamide/MXene hybrid aerogel (PI@MXene) that included the piezoelectric effect.
Research Conclusions and Prospects
To conclude, a multipurpose smart fire-protection and structurally resistant polyimide/MXene composite aerogel (PI@MXene) was created effectively in this study. Temperature detection was robust in PI@MXene, and there was a linear connection between electric voltage and thermal change.
When burnt, PI@MXene was able to constantly activate the fire suppression system in less than 5 seconds, which was much quicker than the typical retardant time of conventional infrared and smoke detectors (more than 100 s).
Even at the fifth burn test, the fire-warning technology could be activated in less than 4 seconds. Furthermore, it demonstrated exceptional fire retardancy and thermal inertness.
The maximal heat release rate of the PI@MXene aerogel was substantially lower than that of the PI aerogel. Furthermore, it also showed remarkable mechanical durability, heat resistance, and piezoelectric sensing.
The developed PI@MXene can identify both delicate human movement and variable large-scale mobility, which opens up exciting possibilities in healthcare monitoring, fire surveillance systems, and human-machine contact.
As a result, this research adds to our understanding of making and using upcoming sophisticated fire-protection aerogels.
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Jiang, C. et al. (2022). Mechanically robust and multifunctional polyimide/MXene composite aerogel for intelligent fire protection. Chemical Engineering Journal. Available at: https://www.sciencedirect.com/science/article/abs/pii/S1385894722001383?via%3Dihub