Stevens Institute of Technology professor Dilhan M. Kalyon and members of his research team, PhD student Semra Senturk-Ozer and senior research associates Dr. Halil Gevgilili, and Dr. Nebahat Degirmenbasi (currently an associate professor at Gazi University in Turkey), have developed a new type of nanoscale material, which they call nanobursa. These new nanomaterials have a nesting pouch structure; the name of the material is based on the Latin word bursa, which means sac or pouch. The nanobursa materials are composed of metal nanoparticles supported on carbon nanotubes, which are in turn encapsulated into polymeric nanofibers or nanocages.
The fabrication and characterization of nanobursa materials is described in a recent publication: “A nanobursa mesh: a graded electrospun nanofiber mesh with metal nanoparticles on carbon nanotubes.” The article appeared in the Royal Society of Chemistry journal Nanoscale: a high impact journal publishing experimental and theoretical work across the breadth of nanoscience and nanotechnology (www.rsc.org/nanoscale): Nanoscale, 2014, 6, 8527, DOI: 10.1039/c4nr01145g.
The fabrication of nanobursa materials became possible through development by Professor Kalyon and associates of a novel hybrid processing method that combines twin-screw extrusion and electrospinning. Prof. Kalyon indicates that, “the hybrid process allows time-dependent feeding and incorporation of multiple ingredients to produce new types of nanobursa meshes, which can be easily graded in composition, porosity and functionality.”
The researchers demonstrated the nanobursa concept by producing a material with consecutive layers of cobalt, silver, platinum and palladium nanoparticles with sizes of 1-20 nm supported on 20-30-nm sized multi-walled carbon nanotubes, which are incorporated into polymeric nanofibers with a diameter of about 200 nm.
According to Michael Bruno, Feiler Chair Professor and Dean, School of Engineering and Science, “the nanobursa is a very interesting development that can be used in many novel applications.”
For example, the simulations of Professor Simon G. Podkolzin, an associate professor in the Department of Chemical Engineering and Materials Science at Stevens, and PhD student Tao Chen, who participated in the development, have shown that the functional grading of metal nanoparticles in nanobursa materials can be used as catalyst layers for consecutive chemical reactions.
As another example, in sensor applications, functionally graded layers with different nanoparticles can selectively respond to different chemicals, thus, significantly expanding the utility of such sensors. Similarly, in environmental sorption applications, each functionalized nanobursa layer can selectively target a specific pollutant for more effective overall purification. The choices of the polymer, porosity, metal functionalization and grading can be tailored for specific applications.