Materials Science

Spongy Clay?

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Science  21 Oct 2005:
Vol. 310, Issue 5747, pp. 407
DOI: 10.1126/science.310.5747.407c

Exfoliated clays have been used to reinforce and compatibilize polymeric materials. Clays have also been added to temperature-responsive hydrogels to improve their properties by strengthening the hydrogels without severely degrading their thermoresponsive behavior. Recently, a technique was found to make clay aerogels, which are highly porous structures with very low densities. Bandi et al. infiltrated a hydrophilic clay aerogel with N-isopropylacryl-amide monomer, which was polymerized in situ in order to produce a polymer-clay composite that preserves the aerogel structure of the clay. The resulting composite retains a low density and good stability, with phase transition and swelling behavior similar to that of the unmodified polymer. The clay aerogel improved the structural integrity of the polymer. At the same time, the polymer prevented loss of the aerogel structure when the composite was immersed in water, even though the unmodified hydrogel has little structural integrity of its own. The composites could be cycled through several dehydration-hydration cycles without any breakdown in the structure or performance of the aerogel hydrogel. — MSL

Macromolecules 10.1021/ma051698+ (2005).

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