[New] Smart barriers for biochemical protective clothing: self-sensing, self-responsive, self-cleaning, self-healing!

Biochemical protective suits usually need to deal with very complicated hazardous environments. Under special circumstances, they need to be equipped with liquid-tight or air-tight protective clothing. They are toxic and harmful to liquids, gases, smoke, solid-state chemicals, biological toxicants, and military toxic gases. And nuclear pollution plays a full protective role. Such protective clothing must sacrifice comfort while ensuring protection performance. Therefore, it is equally important to study biochemical protective clothing in the future how to achieve better protection performance, reduce weight and heat stress, and improve the comfort of protective clothing.

Smart barrier film material enables self-perception ("sensor" function), self-responsive ("actuator" function), and self-adapting ability to the surface of biochemical protective clothing for toxic and harmful substances, and can be adjusted according to the external environment while ensuring protection performance. Protective clothing breathable, moisture permeability, or play a role in self-sterilization or self-cleaning, can greatly increase the protective performance and comfort of biochemical protective clothing.

Barrier material with "sensor" function

Existing research discovers that smart materials that can sense chemical and biological stimuli (including chemical properties, pH, ionic strength, heat of reaction, moisture, surface tension, biological surface functionalities, etc.) include conductive polymers, heat-sensitive aerogels, Chrome materials, active adsorbents, and deformed materials. Among them, conductive polymer is a kind of biochemical intelligent protection sensor material with great application potential. For example, polymer-doped polypyrrole, polythiophene, and polyaniline (PANI) can be used as sensors for detecting volatile and liquid chemicals. Yes: When these conductive substances doped with special substances are exposed to substances with oxidation/reduction, “doping and dedoping” reactions occur, and the presence of harmful substances can be detected by monitoring the resistivity of conductive polymers. .

Polyaniline-Inserted Films with MoO 3 as the Substrate can Detect Formaldehyde and Acetaldehyde at Concentrations as Low as 25mg/kg

In addition, enzymes can also be used to detect organic phosphate chemicals. A sensor developed by Agentase, which combines acetylcholine, acetylcholinesterase, urea, urease, and pH-sensitive dyes, and it can quickly respond to temperature changes.

Barrier material with "actuator" function

The shape-memory polymer material has the ability to maintain a temporary shape, and can restore the original shape when subjected to appropriate external stimuli, and has many advantages such as low density, large recoverable deformation, easy processing and shaping, adjustable deformation temperature, and the like. The "actuator" function of self-resistance barrier material has broad application prospects. At present, related research has focused on thermally-induced shape memory polymers. For example, the shape-memory polyurethane can use its heat-activated properties to provide a low-temperature (<Tg), low-breath-retention thermal effect, and a high-temperature (>Tg), high-gas permeability heat dissipation effect, thereby fully improving the fabric's wearing comfort. Shape memory polyurethanes have also been observed to have a moisture-sensitive effect, which means that the air permeability of shape-memory polyurethane barrier films can also be adjusted by changes in humidity.

Humidity and Temperature of Shape Memory Polyurethane Material Stimulate Shape Change

Currently, commercially available shape-memory polyurethane materials include shape-memory polyurethane heat-sensitive breathable films developed by Mitsubishi Heavy Industries of Japan (SMP Technologies) and shape-memory polyurethane-based film materials (developed by Ahlstrom, Finland). The breathable, integral film is sandwiched between two layers of microfiber spunbonded polypropylene nonwoven fabric).

In addition, the electro-braked nanoporous polymer membranes prepared by grafting ion-gels have also shown great potential for application in biochemical protective clothing, due to the application and elimination of electric fields due to the presence of ions within the nanopores. The gel expands and contracts so that the pore size can be adjusted as needed to increase air permeability.

Grafting principle of grafted ion gel polyester nanoporous membrane

Adaptive barrier film and its application in biochemical protective clothing

Adaptive smart materials can provide immediate protection for wearers in response to external stimuli, such as self-cleaning or self-healing, can clean the surface of harmful chemicals in time, or repair defects on the surface of protective clothing to prevent the entry of harmful substances, enabling smarter Protection.

LLNL developed membrane material with carbon nanotube pores

The Lawrence Livermore National Laboratory (LLNL) developed a membrane material called “second skin” in 2016. This material has neat arrays of carbon nanotube pores with a size of less than 5 nm. Better than GORE-TEX film material. At the same time, because the size of the biological virus is usually greater than 10 nm, it has a good barrier against invasion of biological viruses. To prevent the intrusion of even smaller chemicals, researchers are using chemical-responsive functional groups to surface-modify carbon nanotube membranes to achieve selective blockage of harmful chemicals. At the same time, the researchers are still conducting another interesting "self-cleaning" defense method research, that is, when reacting with harmful chemicals, the surface film material automatically fall off, in order to achieve the purpose of self-cleaning. It is reported that this research is funded by the Defense Threat Reduction Agency (DTRA) and will be initially evaluated by early 2018 and is expected to be used in its future biochemical protective clothing system.

For detailed information, please refer to the article "New progress in the research and application of textiles for intelligent security protection", Textile Review (Supply Textiles for Industry).