A touch of gold makes a swell absorbent foam

The properties of gold nanoparticles could be combined with those of polydimethylsiloxane (PDMS) to provide a sustainable and practical solution for water treatment, according to a team from the Jawaharlal Nehru Center for Advanced Scientific Research (Bangalore, India; www.jncasr.ac.in). The team, headed by professor Giridhar U. Kulkarni, has synthesized low-density, highly compressible, porous foams of PDMS with incorporated Au nanoparticles (10–50 nm) by a single-step process, with water as a medium. The foams exhibited high swelling ability (about 600%) against benzene, toluene, ethylbenzene and xylene (BTEX) — a property that can be exploited in the removal of oil spills from water. The team prepared three samples of AuPDMS using 0.1-, 0.5- and 1-mM aqueous solutions of KAuCl4. The weight percentage of Au nanoparticles in the foam was 0.01, 0.03 and 0.06%. Higher Au content resulted in uncured, sticky AuPDMS gels. The particles are formed inside the PDMS matrix at the cross-linking Si-H sites. The foams regained shape following decompression and did not disintegrate. The pore volume (5.52 cm3/g) is much higher than that of just PDMS. The foams exhibit high resistance to harsh chemical environments, such as concentrated…