Clevertex - Grado Zero Espace Srl
Clevertex - Grado Zero Espace Srl
Clevertex - Grado Zero Espace Srl
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2.6 Stimuli sensitive polymers<br />
2.6.1 Description<br />
This chapter describes the current innovations and commercialisations in fabrics that change their<br />
responses to external stimuli or environmental changes such as temperature, humidity, pH, light,<br />
electrical field, chemicals, ionic strength or stress. The responses excite changes, for instance, in<br />
shape, structure, surface characteristics, solubility, formation of an intricate molecular self-assembly or<br />
a sol-to-gel transition.<br />
These polymers can be processed in fibres, or can be applied on the fibre surface in order to obtain<br />
specific properties.<br />
2.6.2 Applications in the clothing sector<br />
2.6.2.1 Research projects and products<br />
Taking for instance humidity as a stimulus, the wicking performance of a fabric can vary according to<br />
the humidity level. A research group at the Centre of Biomimetics at University of Reading, UK, tries to<br />
imitate the opening and closing of pine cones. When cones are hanging on the tree, they are firm and<br />
closed. However, when they ripen and fall to the ground, they open in order to release the seeds. This<br />
works because the scales of the cone consist of layers of two materials that react differently to<br />
humidity. When the cone desiccates, the scales will bend, because one of its sides will expand more<br />
than the other.<br />
In co-operation with the London College of Fashion they are researching the material, which they think<br />
could be in everyday use by people within a few years. The smart garments will consist of a top layer<br />
of tiny spikes of water-absorbent material, possibly wool. When the wearer of the clothing gets hot and<br />
sweats, the tiny spikes in the material will react to the moisture and automatically open up, so that air<br />
from the outside can get through the material to cool the wearer. When the wearer stops sweating and<br />
the skin dries, the fins will close down again to stop air getting in. The lower layer will be of material<br />
that is not porous so that rain can never get through from the outside, whether the spikes are open or<br />
closed [193, 194].<br />
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