Cornell University Researchers Use Copolymers to Self Assemble Metamaterials

Research teams from Cornell University have developed a chemical method to facilitate self assembly of metamaterials in three dimensions. Metamaterials have excellent optical properties which make them ideal for use in superlenses or cloaking devices.

However, traditionally scientists have only been able to create very thin layers of metamaterials through atomic sputtering and electron beam lithography. Cornell University researchers have been able to design 3-D structures of metamaterials through use of block copolymers.

While a copolymer consists of molecules that are connected to each other to form a solid or semi solid material, a block copolymer is formed by connecting two copolymer molecules at the ends in such a manner that each end connects to other ends that are matching to form repeating geometric shapes or a network of shapes known as gyroids. The repeating patterns can measure only a few nanometres and tri polymers can also be used to create even more complex patterns. Once the formation of the structure is done, one of the copolymers can be dissolved with only the 3-D mould remaining, which can be filled with metals like gold or silver. After this procedure, the second copolymer too is dissolved leaving behind a metal structure that is porous in nature. The research paper proposes to create nanoscale metal gyroids, which allow light to pass through. This will help in the designing of materials that have negative index of refraction. Lenses made from such materials could make images smaller than light wavelengths such as viruses, proteins and DNA to be viewed easily. The research programme is supported by King Abdullah University of Science and Technology.