Stuck on “Nanoglue”
Materials that don’t normally stick together can be bonded by using a one-nanometer-high layer of self-assembling polymer chains, a Rensselaer team has discovered. The extraordinarily thin “nanoglue,” which gains strength as temperatures rise, could be a breakthrough for next-generation computer chips, and it could also be useful in such applications as high-temperature coatings.
The nanoglue consists of chains of carbon and hydrogen atoms customized with appropriate molecules at the ends, according to Ganapathiraman Ramanath, professor of materials science and engineering, who leads the research team. Ramanath’s work is funded by the NSF, the U.S.-Israel Binational Foundation, and the Interconnect Focus Center-New York at Rensselaer.
The polymer used in the nanoglue is inexpensive and commercially available, but Ramanath’s method of treating it is new.
As reported in Nature, his first nanoglue, consisting of chains with sulfur at one end, is designed to join copper components with other materials on computer chips, but he believes customizing the chains with different materials at the ends would make it possible to bond other materials.
The one-nanometer-long polymer chains self-assemble into a small forest standing on a copper surface, and the sulfur ends bond with the copper. Ordinarily, the copper-sulfur bonds break and the polymer falls off at about 400°C. Ramanath’s team added a silica layer to form a copper-polymer-silica sandwich. When the temperature rises, the polymer has no place to go, and its molecules begin forming very strong bonds with the adjoining materials. This glue layer is at least 10 times thinner than the best materials now used on chips.
See also: Nanoglue Can Bond Nearly Anything (Rensselaer Research Review)