NSF NIRT Grant 0506941

University Louisville, Massachusetts Institute of Technology, University Massachusetts Amherst

Polymers dissolved in volatile solvents can be directed to self-assemble into suspended nanofiber bridges through surface tension driven capillary thinning. This points towards a single step approach to forming suspended 3D structures in a considerably more simple way than by standard microfabrication processes. Fibers form when the polymer liquid is brushed by hand over a corrugated surface, as shown in the cartoon. To the right of the cartoon is a portion of an array and a closeup of polymer microfibers. The large mounds of polymer, compared to the fiber diameter, show how dramatically the fibers have thinned through the capillary forces. Carbon nanotubes can also be suspended, by dispersing them in the liquid polymer, forming fibers, and then thermally decomposing the polymer. The bottom images show the one bridge before and after decomposition of the polymer. [2] Bridges under 10 nm wide have been observed to form.

The study considers several ways to extend these results including: improving understanding of the process through rheological modeling and measurements, improving control of the process through automation, employing various polymers for various applications including the synthesis of new polymers, and constructing application specific devices based on the suspended fibers.