Just like how people end up living in the bitter, frostbitten cold, other people end up living in hot, arid regions. In the cold you need heat — something easily remedied with proper clothing and heating equipment — but in the heat, you need water, which is something you can’t quite create out of man-made components. However, researchers have created a new special coating that, when applied to cotton, can suck water right out of the air. On top of that, once the cotton gets hot enough, it can automatically drain itself.
Researchers at Eindhoven University of Technology in the Netherlands and Hong Kong Polytechnic University teamed up and created a special polymer, called PNIPAAm, that is applied to a cotton fabric. Up to a temperature of 93.2 Fahrenheit (or 34 Celsius), the coating and cotton duo is extremely absorbent, able to suck water right out of a misty atmosphere. During this phase, the cotton fabric can hold up to 340% its own weight in water, whereas without the special polymer it can only hold 18% — a dramatic increase. When the fabric reaches a temperature higher than that 93.2 Fahrenheit maximum, it actually becomes water repellent, and releases the stored water. The cotton treated with the polymer doesn’t “run out,” so to speak, and once it drains all of its liquid it can be reused. Perhaps best of all, the water it collects and drains is totally pure, making it perfectly potable.
In theory, this water-collection system can be set up in arid areas, and essentially be forgotten about while it does its work. It can absorb water during the cooler hours of the day — generally morning and night — and drain the water either into a collection basin or over crops after the temperature reaches above that 93.2F threshold. Of course, the surrounding area will need to have some sort of fog or misty air in order for the collection system to obtain large amounts of water in the first place. However, even arid, desert landscapes have a mist or fog roll in at nighttime, which aligns with the lower temperatures required to collect the water. On top of that all, because the cotton pulls water directly from mist in the air, it doesn’t require any other force of nature — such as wind — to work, and simply relies on temperature changes alone.
Another advantage of the cotton and polymer duo is that cotton fabric is cheap to make, and you can make it just about anywhere. According to researcher Catarina Esteves at Eindhoven University of Technology, the polymer isn’t expensive either, and only raises the cost of the overall production slightly.
The researchers’ work isn’t yet done, as they’re now exploring how to increase the amount of water the cotton fabric can hold, as well as change the temperature at which the fabric collects and releases water. In theory, this could lead to different fabrics for regions of different temperature. The researchers are also exploring other applications of the technology, such as clothes that absorb a person’s sweat, and water collection systems for survival gear. Maybe one day the technology will get to a point where something that looks like a fabric farm will actually be an automated system for watering crops.