In the Spider's Web: Hygroscopic Adhesives Inspired by Nature
Whether in high humidity or heavy rainfall, spiders always manage to keep their prey in their webs. This is made possible by a special adhesive which spiders distribute drop by drop on the silky strands of their webs. A team of researchers from the University of Akron (USA) has now got to the bottom of this secret.
Gluing in outdoor areas or damp spaces can be a difficult matter. The reason: dampness between layers. The damp gets between the surface, for example tiles, and the adhesive. As a consequence, the bonding detaches and the tiles fall off. But a more thorough look at a spider's web shows that adhesives and dampness can get along well with one another. As researchers at the University of Akron in the USA have discovered, the adhesive which the spider distributes on its web consists of three elements: two glycoproteins (consisting of amino acids and sugar molecules), a collection of low-molecular organic and inorganic compounds (hygroscopic molecules) and water.
Whereas glycoproteins are responsible for the bonding, the hygroscopic molecules take on a previously unknown function, which the scientists discovered: they bind accumulated water and pull it into the inside of the mass. This means that the adhesive force between the adhesive and the surface remains in place. Glycoproteins and hygroscopic molecules therefore work together to ensure the spider's prey is stuck to the web despite damp conditions. These findings could be important for the development of damp-resistant adhesives.