IMAGE:This schematic shows the synthesis of organic-inorganic shish kebab-like nanohybrids composed of periodic nanodisk-like kebabs. view more <\/p>\n
Credit: Credit: Zhiqun Lin <\/p>\n
Researchers have developed a novel technique for crafting nanometer-scale necklaces based on tiny star-like structures threaded onto a polymeric backbone. The technique could provide a new way to produce hybrid organic-inorganic shish kebab structures from semiconducting, magnetic, ferroelectric and other materials that may afford useful nanoscale properties. <\/p>\n
The researchers have so far made nano-necklaces with up to 55 nanodisks. The template-based process grows amphiphilic worm-like diblock copolymers through a living polymerization technique in which the polymeric structures serve as nanoreactors that form laterally connecting nanocrystalline structures based on a variety of precursor materials. The nanodisks average about ten nanometers in diameter and four nanometers in thickness, and are about two nanometers apart. <\/p>\n
\"Our goal was to develop an unconventional, yet robust, strategy for making a large variety of organic-inorganic hybrid shish kebabs,\" said Zhiqun Lin, a professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. \"This is a general technique for making these unusual structures. Now that we have demonstrated it, we believe there is a nearly endless list of materials we can use to craft these nano-necklaces.\" <\/p>\n
The research was supported by the Air Force Office of Scientific Research and the National Science Foundation. The results were scheduled to be published on March 27 in the journal Science Advances, published by the American Association for the Advancement of Science (AAAS). <\/p>\n
The one-dimensional nano-necklaces could have optical, electronic, optoelectronic, sensing and magnetic applications. The researchers have so far produced structures from cadmium selenide (CdSe), barium titanate (BaTiO3) and iron oxide (Fe3O4), but believe many other materials - including gold--could also be used. <\/p>\n
The technique begins with formation of inclusion complexes made of alpha-cyclodextrins, cyclic oligosaccharides composed of six glucose units. The alpha-cyclodextrins, which are hollow in the center, thread themselves onto a polyethylene glycol (PEG) chain in an established self-assembly process. The polymer backbone on which the alpha-cyclodextrins are threaded is capped by a larger stoppering agent to retain the tiny structures. <\/p>\n
Each alpha-cyclodextrin has 18 hydroxyl (OH) groups that can be converted into bromine (Br) groups through an esterification process. Diblock polymer \"nanoworm\" structures are then grown from these bromine groups in solution. Formed from poly(acrylic acid)-block polystyrene (PAA-b-PS), the worm-like diblock copolymers are made up of inner poly(acrylic acid) (PAA) blocks that are hydrophilic, and outer polystyrene (PS) blocks that are hydrophobic. Because so many diblocks grow on each alpha-cyclodextrin, their crowding stretches the polymer backbone. <\/p>\n
Finally, metallic ion precursors are preferentially incorporated into the space occupied by inner PAA blocks of worm-like diblock copolymer nanoreactors, forming crystals. These crystals connect the once separate structures, creating the nano-necklaces - which resemble tiny centipedes. <\/p>\n
<\/p>\n
Read the original post: <\/p>\n
Nanoscale worms provide new route to nano-necklace structures<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" IMAGE:This schematic shows the synthesis of organic-inorganic shish kebab-like nanohybrids composed of periodic nanodisk-like kebabs. view more Credit: Credit: Zhiqun Lin Researchers have developed a novel technique for crafting nanometer-scale necklaces based on tiny star-like structures threaded onto a polymeric backbone. The technique could provide a new way to produce hybrid organic-inorganic shish kebab structures from semiconducting, magnetic, ferroelectric and other materials that may afford useful nanoscale properties Continue reading