Sci­en­tists cre­ate ni­tride foam that soaks car­bon diox­ide

Chemical Industry Digest - - New Developments -

Rice Uni­ver­sity ,Texas, sci­en­tists have cre­ated light foam from two-di­men­sional sheets of hexag­o­nal­boron ni­tride (h-BN) that ab­sorbs car­bon diox­ide.

They dis­cov­ered freeze-dry­ing hexag­o­nal boron ni­tride turned it into macro-scale foam that dis­in­te­grates in liq­uids. But ad­ding a bit of polyvinyl al­co­hol (PVA) into the mix trans­formed it into a far more ro­bust and use­ful ma­te­rial.

The foam is highly por­ous and its prop­er­ties can be tuned for use in air fil­ters and as gas ab­sorp- tion ma­te­ri­als, ac­cord­ing to sci­en­tist Pulickel Ajayan, Rice Uni­ver­sity. The polyvinyl al­co­hol serves as glue. Mixed into a so­lu­tion with flakes of h-BN, it binds the junc­tions as the mi­cro­scopic sheets ar­range them­selves into a lat­tice when freeze-dried. The one-step process is scal­able, the re­searchers said.

“Even a very small amount of PVA works,” said co-author and Rice post­doc­toral re­searcher Chan­dra Sekhar Ti­wary. “It helps make the foam stiff by glu­ing the in­ter­con­nects be­tween the h-BN sheets - and at the same time, it hardly changes the sur­face area at all.”

In molec­u­lar dy­nam­ics sim­u­la­tions, the foam ad­sorbed 340 per­cent of its own weight in car­bon diox­ide. The green­house gas can be evap­o­rated out of the ma­te­rial, which can be reused re­peat­edly, Ti­wary said. When coated with PDMS, an­other poly­mer, the foam be­comes an ef­fec­tive shield from lasers that could be used in bio­med­i­cal, elec­tron­ics and other ap­pli­ca­tions,” he added.

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