# Presentation: 662991

## CAREER: Rational Synthesis and Studies of Functionalized Carbon NanotubesStanislaus S. Wong, SUNY Stony Brook, DMR 0348239

_**Insulating coating on Carbon Nanotubes**__**:**_**  **
**-Renders tubes ****oxidation-resistant****.**
**Excellent gate insulating material for ****field effect transistor applications.**
**Highly desirable for applications in ****optics **
**and in ****biomedicine****.**
_**Silylation:**_** ****Mild, room-temperature, and relatively nondestructive method**** ****(structural)**** for functionalization of nanotubes with Si-containing species. **
_**Electrochemical approach (benefits) :**_** **
**(a) ****mild****, non-destructive; (b) ****minimal amts. **
**of reactants**** and reaction steps.**** **
**(c) run under ****aqueous or ethanol conditions****; (d) ****Ambient temperature and pressure**** conditions under reasonable reaction times.**** **

**Notes:**
Silylation: Herein we present, to the best of our knowledge, the first report of effective silylation of raw, pristine single-walled carbon nanotubes (SWNTs). Specifically, commercially available CoMoCAT SWNTs were functionalized at their ends and sidewalls (a) with trimethoxysilane and in a separate experiment, (b) with hexaphenyldisilane. Raman analyses demonstrated selective reactivity of predominantly smaller-diameter semiconducting nanotubes. Transmission electron microscopy (TEM), high-resolution TEM, scanning electron microscopy, and atomic force microscopy showed that the functionalization reaction was structurally non-destructive to the tube integrity. Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (Si NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray (EDS) data provided evidence for chemical attachment of organosilanes onto the carbon nanotube surface. UV-visible data also yielded evidence for selectivity and functionalization. These results are consistent with our initial expectation that smaller-diameter tubes would be more reactive than larger-diameter tubes towards silylation. The fundamental point to note is that coatings of dielectric materials can be placed onto SWNT ends and sidewalls through a well-defined, relatively mild molecular reaction, which is structurally non-destructive to the nanotube itself.
Ref.: T. Hemraj-Benny and S.S. Wong, “Silylation of Single-Walled Carbon Nanotubes”, Chem. Mater., 18(20), 4827-4839 (2006). Artwork as cover figure on Nov. 14, Nov. 28, Dec. 12, and Dec. 26, 2006 issues.

Electrodeposition: Control over the thickness of a silica coating on single-walled carbon nanotubes (SWNTs) is highly desirable for applications in optics and in biomedicine. Moreover, a silica coating on SWNTs would also aid in avoiding tube-tube contact and bundle formation as well as tube oxidation, a scenario conducive to the use of appropriately functionalized carbon nanotubes as individualized gate dielectric materials in field effect transistors. In this work, we have developed two feasible and reliable means with which to coat SWNTs with various reproducible thicknesses of silica using an electrochemical sol-gel process. In one procedure, a SWNT mat was used as a working electrode for the direct deposition of silica. In the second, nanotubes were dispersed in solution and silica was deposited onto these solubilized nanotubes in the presence of a platinum working electrode. Applying a negative potential results in the condensation of a silica film onto the SWNT surface. The thickness of the silica coating can be controllably altered by varying the potential of the working electrode as well as the concentration of the sol solution. These methodologies have the advantages of ease of use, environmental friendliness, and utilization of relatively mild reaction conditions.
Ref.: Mandakini Kanungo, Hugh S. Isaacs, and Stanislaus S. Wong, “Quantitative Control over Electrodeposition of Silica films onto Single-Walled Carbon Nanotube Surfaces”, invited contribution, Richard E. Smalley Memorial issue, J. Phys. Chem. C, in press.

## CAREER: Rational Synthesis and Studies of 

- - **Two undergraduates** (H. Gerardi and W. Zaman), **four graduate** students (T. Hemraj-Benny, H. Zhou, F. Zhang, and T-J. Park), and **one postdoctoral fellow** (M. Kanungo) contributed substantially to this work as well as to related projects.
- - Zaman received a HHMI (Howard Hughes Medical Institute) scholarship (Stony Brook).
- - Gerardi earned an Undergraduate Recognition Award in 2007 and was a co-winner of the 2006 Emerson Award and the Lap Chan Scholarship as the outstanding junior chemistry major in the Department.
- - Hemraj-Benny and Park earned recognition as recipients of the Chemistry Award for Excellence in Doctoral Research in 2007.

**Outreach:**
- - Hosted Amanda Tiano on a 2007 DOE _Summer Undergraduate Laboratory Internship (SULI)._ In her project, he used NSF-funded facilities and supplies.
- - _Primary Organizer_ of the 18th Bigeleisen lecture, entitled “Nanowires, Nanoscience, and Emerging Nanotechnologies”, given by Professor Charles M. Lieber (Harvard University), on December 15, 2006.

**CAREER: Rational Synthesis and Studies of **
**Functionalized Carbon Nanotubes****Stanislaus S. Wong, SUNY Stony Brook, DMR 0348239**

**Notes:**
Two undergraduates (W. Zaman  and H. Gerardi), four graduate students (Tirandai Hemraj, Tae- Jin Park, Hongjun Zhou, and Fen Zhang), and one postdoctoral fellow (Mandakini Kanungo) contributed to the work presented.  Kanungo and Hemraj-Benny participated in electrodeposition and silylation experiments, respectively. Zaman was involved with nanotube arrays, and Gerardi performed large scale chemical functionalization procedures, associated with optimizing ozonolysis conditions. She was also involved in spectroscopic analyses of samples. Zhou, Zhang, and Park worked on an off-shoot of these efforts towards understanding the chemistry and physics of non-carbon nanomaterials, including ternary metal oxide and fluoride nanostructures.

One of the PI’s outreach initiatives was to generate added intellectual exposure to BNL facilities for graduate and undergraduate students. The PI hosted Amanda Tiano (undergraduate from SUNY Binghamton) on a Department of Energy Summer Undergraduate Laboratory Internship to perform research using various instrumentation and facilities at Brookhaven National Laboratory and at Stony Brook. The PI was also the graduate recruitment chair responsible for prospective student visits (Spring 2007). Moreover, he instituted and organized the logistics of graduate student-sponsored seminars at Stony Brook, bringing in Dr. Robert Tycho from the NIH in 2006 and Professor Michael Duncan from the University of Georgia in 2007. The PI was also responsible for the overall coordination, logistics, and planning of the 18th Bigeleisen lecture, entitled “Nanowires, Nanoscience, and Emerging Nanotechnologies”, given by Dr. Charles M. Lieber (Harvard University), on December 15, 2006.