Elastane polymer

One important elastane polymer that can be made by polymerization in a Ziegler-Natta fashion is rubber. Natural rubber is a polymeric terpene (Chapter 51) made from mevalonic acid and has a branched structure with regular trisubstituted alkenes, which are all in the Z-configuration. 

To make a polymer it is necessary to react aryl diisocyanates with diols. Some important polymers -of the type, called elastanes, are made by using long-chain aliphatic diols from partly polymerized epoxides, rather like those discussed in the last section, and reacting them with diaryl diisocyanates to give a pre-polymer . 

Spandex (as it s called in North America Europe knows the same material as elastane and the Brits refer to it as lycra, but that s confusing because Lycra is actually a trade name) is a rigid copolymer of polyurethane and polyurea and is a rubbery material, like polypropylene oxide. These two polymers do not mix well, so tiny domains of each polymer form. It s this separation (of the hard bits from the soft bits) that gives Spiindex its stretchy, yet strong, behavior. 

T Mihailovic, K Asanovic, Lj Simovic, P Skundric, Influence of an antimicrobial treatment on the strength properties of polyamide/elastane wefl-knitted fidtric , J of Appl Polymer Sci, 2006 103(6) 4012-4019. 

Occasionally, manmade libers are also sensitive to oxidative stress. Certain types of polymers, such as elastanes, are known to react with oxygen species or may be activated to add oxygen (autoxi-dation). As a long-term conseqnence, the fibers will lose their form-giving properties, and underwear or swimwear may lose its shape. 

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