New research published in the Proceedings of the National Academy of Sciences shows direct 3D experimental evidence of new mesoatom shapes and symmetries that occur in a special twin boundary in soft matter.
Dr. Ned Thomas, a professor in the Department of Materials Science and Engineering at Texas A&M University, studies twin boundaries, a type of planar defect. Twin boundaries occur in a soft matter block copolymer that forms a double diamond (DD) crystal from structural building blocks of polystyrene (PS) chains covalently linked to polydimethylsiloxane (PDMS) chains. Each mesoatom is comprised of thousands of PS-PDMS molecules and millions of atoms.
"A mesoatom is an intermediate atom. It's a new concept, which is at a much larger scale," Thomas said. "Atoms we know are the smallest kinds of individual chunks, usually represented by spheres and thought to be indivisible."
Mesoatoms in a soft DD crystal are analogous to single carbon atom building blocks in hard diamond (D) crystals. A DD mesoatom also has the same bonding, geometry and crystal structure as a carbon atom in single diamond.
"What we're interested in is the size of these mesoatoms because they're 1,000s of times bigger than atoms," he said. "It turns out these building blocks are on the order of the wavelength of light. So now we have an opportunity in the future to think about how to adjust the structure on the scale that matters to create novel light-defect interactions."
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