CBET Award Achievements
Notable Accomplishments from CBET Awards

Films of Single-Walled Carbon Nanotube by Drop Drying

Matteo Pasquali    Rice University, Houston

Background:  Extensive interdisciplinary research is currently being pursued to apply the unique properties of single-walled carbon nanotubes (SWNT) to everyday applications.  However, developing SWNT-based macroscopic materials, such as fibers, ribbons, and films of pure SWNTs, is a challenging engineering problem.  In this project, researchers employed the evaporation of drops on substrates to form aligned patterns of SWNTs for making films or for nano-fabrication.  This method is potentially applicable to forming continuous thin coatings of SWNTs on substrates.

Results:  A thin film (~100 nm thick) of SWNTs is formed using the evaporation of a drop of an aqueous dispersion of SWNTs; the film formation process is explained by a well-known theory of drop-drying of polymer solutions.  Therefore, the formation of a crust of SWNTs at the free surface of an evaporating drop parallels a similar process in polymer solutions.

Scientific Uniqueness:  The evaporation of drops is commonly used for patterned deposition of solute onto non-porous substrate, for example, in DNA microarrays, nanolithography and protein crystallization; in the same process, a 'crusting' phenomenon is also observed for some materials.  A drop of aqueous solution of SWNTs was dried, and the crusting was observed for a particular kind of surfactant.  The presence of SWNTs in the crust was confirmed with Raman fluorescence sprectroscopy and transmission electron miscorscope (TEM); the crust was analyzed with atomic force microscope (AFM) and scanning electron microscope (SEM), and the thickness was found to be between 10 and 100 nm.

This work is notable because it focuses upon understanding the effects of changing molecular features of polymeric species.  Once formed the molecular features of the polymer are then formed into polymeric membranes with specific gas permeation properties imparted by the molecular features.

Matteo Pasquali Image 1

Birefringence patterns of a film of SWNTs;
the film is formed when a drop of an aqueous
solution of SWNTs is dried.

Credit:  Matteo Pasquali, Rice University-Houston

Matteo Pasquali Image 1

Research supported by this grant was featured
on the cover of Advanced Materials.

Credit:  Matteo Pasquali, Rice University-Houston and
Advanced Materials; Volume 18, No. 1, January 5, 2006.

Program Officer:   Michael Plesniak
NSF Award Number:   0134389
Award Title:   CAREER: Polymer Molecules in Complex Flows
PI Name:   Matteo Pasquali
Institution Name:   Rice University-Houston
Program Element:   1443
CBET Nugget:   FY 2006

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This Nugget was Updated on 24 September 2008.