Low density collapsed absorbent foams materials that, upon contact with aqueous fluids, in particular urine, can expand and absorb these fluids. These low density foams typically have an expanded thickness from about 6 to about 10 times the thickness of the foams in their collapsed state. These...http://www.google.com.au/patents/US5741581?utm_source=gb-gplus-sharePatent US5741581 - Absorbent foam materials for aqueous fluids made from high internal phase emulsions having very high water-to-oil ratios 
