2-D Polymers Step Up In Size

Two-dimensional materials such as graphene offer a diverse range of enticing physical and chemical properties. Yet they all seem to pose a common challenge: Can researchers readily synthesize thin sheets that are large enough to be useful? A research team led by Benjamin T. King of the University of Nevada, Reno; A. Dieter Schlüter of ETH Zurich; and Markus Lackinger of the Technical University of Munich show that the answer is yes for a porous 2-D polymer, which the researchers created in square-centimeter monolayers (J. Am. Chem. Soc. 2015, DOI: 10.1021/ja512018j). To make the material, the team dispersed the monomer over water. “We’re basically using a pond scum approach,” King says. The monomer’s three anthracene arms extend like trefoil leaves from a triptycene core, which also sports a hydrophilic diethylene glycol tail to keep the molecules anchored in the water. The team polymerized the organized monolayer by illuminating it with blue light. The process links the anthracene arms of adjacent monomers, forming a large 2-D sheet. The freestanding membranes contain about 60 trillion nanoscopic pores per square centimeter and could be sturdy and stable enough for separation applications, including desalination, King says.