Credit: Courtesy of TU Eindhoven/Bart van Overbeeke
Cotton textile with a hydrophilic PNIPAAm coating
Proposals for a distributed, self-sufficient power grid based on renewable energy have received a lot of attention—but what about water? According to the World Health Organization (WHO) and United Nations Children Fund (UNICEF), more than one in six people worldwide lack access to improved water sources. In addition, the need for potable water is exacerbated in arid regions that have been experiencing ever-hotter summers. Although electricity is a significant resource, water is obviously much more important.
A primary goal has been the distribution of effective, low-cost pumps to increase access to groundwater. Another has been the use of materials that enable the harnessing of water vapor out of the air. Researchers at TU Eindhoven in the Netherlands and Hong Kong Polytechnic University, for example, have developed a new treatment that converts cotton fabric into a superhydrophilic material. The coated textile readily absorbs water from moist air up to over three times (340 percent) its own weight. (For the sake of comparison, untreated cotton fabric only absorbs 18 percent of its weight in water.)
The special treatment was inspired by insects that capture water droplets on their bodies or webs, and consists of a polymer coating with a spongelike microstructure. The coating performs differently depending on the temperature: it absorbs water up to 34 degrees C, but above this threshold its cells close and it repels water. This inherent ability to store and release water automatically could be especially applicable in desert areas with widely-fluctuating diurnal temperatures. Once released, the water is completely pure and safe to drink—or to use for agricultural purposes.
What is particularly exciting about this new technology is its architectural potential. Conventional means of storing and accessing water such as pumps, wells, and troughs are typically confined to the realm of infrastructure or mechanical equipment. But this superhydrophilic treatment for a common fiber material suggests the need for wide-ranging experimentation in design applications for tents, canopies, awnings, and other fabric structures. In this case, water conveyance is not segregated within a discrete system—the material has become the system.
Blaine Brownell is a regularly featured columnist whose stories appear on this website each week. His views and conclusions are not necessarily those of ARCHITECT magazine nor of the American Institute of Architects.