General Instructions:
Abstract submission: An abstract must be submitted before January 31MARCH 30, 2004 for a paper to be considered for presentation and/or publication. It must follow the publishing rules expressed in the enclosed document (Publication Rules). More than one abstract can be submitted by one author or co-author. Abstracts will be evaluated by the Technical Committee and a response indicating the acceptance of the paper will be communicated by exclusively email to the authors email addresses by February 28, 2004. .
Papers: Papers must be submitted by the due date and must correspond to the abstract accepted for presentation. It must follow the publishing rules expressed in the model document that follows (Model Paper for LACCEI Proceedings). More than one paper can be submitted by one author or co-author. To be published in the proceedings, the paper must comply with the publication rules and at least one author must be registered for the conference to present the paper. The Technical Committee will evaluate the papers and will be responsible for the final acceptance or rejection of the proposed paper for publication. Selected papers may be selected for publication in the LACCEI upcoming Journal or may be recommended for publication in any other selected publication.
It is recommended that the paper have the following sections:
Abstract; Introduction; Objectives; Scope of Work; Methodologies; Results (Findings); Conclusions; Recommendations; and References
Presentations: Guidelines for the technical presentations will be presented in the near future. Each conference session will have laptops and LCD projectors with Microsoft Powerpoint.
Example: The following pages contain an example of a paper that follows the LACCEI proceedings publication format rules. Please carefully read the “Model Paper for LACCEI Proceedings” paper for complete detail of format information. Only those papers following the guidelines will be published in the proceedings.
Second LACCEI International Latin American and Caribbean Conference on Construction in the 21st Century (CITC-IIfor Engineering and Technology (LACCETI’2004))
“Sustainability and Innovation in Management and TechnologyChallenges and Opportunities for Engineering Education, Research and Development”
10-122-4 June December, 20034, Hong KongMiami, Florida, USA
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EFFECT OF STRESS-PATH ON THE FAILURE OF CONCRETE UNDER
TRI-AXIAL STRESS STATE
Surface Modification of Carbon Nanotubes Using Poly (Vinyl Alcohol) For Sensor Applications
Model Paper FFor EASEC-8CITC-IILACCEI Proceedings
(Times New Roman Font, Size 142pt, All CapTitle Case, Bold Face, Center)
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First Author, PhDHarindra Vedala, M.S
PositionGraduate Student, Company or UniversityFlorida International University,, CityMiami, State,Florida, CountryUSA
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YoungChulChoiSecond Author, PhD Ing.
Research Scholar, Florida International University, Miami, Florida, USA
Gene Kim, PhD
Senior Staff Engineer, Motorola, Fort Lauderdale, Florida, USA
Position, Company or University, City, State, Country
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Third Author, P.E.Eungmin Lee, M.S
Graduate Student, Florida International University, Miami, Florida, USA
Position, Company or University, City, State, Country
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Won Bong Choi, PhD
Associate Professor, Florida International University, Miami, Florida, USA
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Author Number One1, Author Number Two2 and Author Number Three3
(Times Roman Font, Size 11 pt)
Abstract : (Times New Roman Font, Size 122pt, All CapTitle Case, Bold Face)
Surface modification of the carbon nanotubes plays an important role for their utilization in various applications. In this study, single-wall and multiwall nanotubes were grown on a 1 cm2 silicon dioxide substrate using chemical vapor deposition. The surface of grown nanotubes was modified by polyvinyl alcohol and the wettability on nanotubes was investigated. This functionalisation tends to change the surface of nanotubes into hydrophilic thus increasing its sensitivity. The electrical characterization of these modified nanotubes was performed since it is expected that by adapting analytes onto the polyvinyl alcohol modified nanotubes, the electric transport property of CNT may be changed. Sensor applications of these modified nanotubes are also suggested.
A brief abstract of the current work should be supplied hereresearch work. Abstracts should be not more than 3200 words in length should be typed here and should not contain equations or abbreviations. Must include a statement of relevance, the main objective, the scope of word to be presented, and most significant findings. Do not include figures, tables or illustrations in this section. (Times New Roman Font, Size 101pt, Single spacing, justified).
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Keywords: (Times New Roman Font, Size 122pt, All CapTitle Case, Bold Face)
Font, format, proceedings, conference, appearance, Maximum 5 keywords separated by commas (Times Roman Font, Size 101pt, justifiedjustified, Title Case).Carbon Nanotubes, Surface Modification, PVOH, Sensors, Nanosensors
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1. Introduction (First Heading: Times New Roman Font, Size 12pt, Title Case, Bold Face)
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The excellent mechanical and electrical properties of carbon nanotubes make them attractive to various device applications including sensor applications. Single wall nanotubes have been synthesized into different shapes for various electronic applications (Choi and Choi, 2004).Single wall nanotubes have also been grown selectively to make nanoscale transistors (Choi et al., 2003). Carbon nanotubes based sensors have been shown to have detection capability for gas molecules such as NO2 and other organic vapors (Li et al., 2003). This sensing mechanism is attributed to the changes in the electrical conductivity of these nanotubes caused by the charge transfer from the gas molecule. Moreover due to their large surface area, carbon nanotubes have high sensitivity for gas and chemical vapors at room temperature as compared to conventional metal oxides sensors which operate at high temperatures. The gas sensing capability of the intrinsic nanotubes can be greatly enhanced by functionalisation with different molecules and functional groups. Polymer coated carbon nanotubes have shown high sensitivity and selectivity for gases like NH3 and NO2 (Qi, et al., 2003). While other studies have shown that nanotube based polymer composites can be used for strain sensing (Dharap, et al., 2004). Since carbon nanotubes are hydrophobic in nature they cannot be directly used for applications like relative humidity sensing. Polyvinyl alcohol (PVOH) is well known for its hydrophilic properties. It is atactic yet semicrystalline in nature which becomes surface-active at hydrophobic surface/water interfaces and concentrates at these sites allowing crystallization to occur. It is a water soluble polymer which is used in various industries such as textiles, adhesives, ceramics and paper. Recently its application as a polymer coating on a SAW device for improving the chemical sensing capability was shown (Kozlov et al., 2003), (Penza, et al., 1999). Earlier studies in which PVOH was used for functionalisation of carbon nanotubes mainly focused on improving the mechanical properties of nanotubes (Zhang et al., 2003). Here we present initial results of the effect of functionalisation by PVOH. The wettability behavior of nanotubes is studied as it plays a crucial role in adsorption and sensing of the analytes. These PVOH functionalised nanotubes may be used for sensing gases like CO and biomolecules which are not detected by pristine nanotubes.
2. Experimental Details
Carbon nanotubes were grown on 1cm2 SiO2/Si substrates using CVD process. Single wall tubes were grown on iron thin film at 900°C by using methane and ethylene as precursors, while multiwall carbon nanotubes were grown on the similar substrate at 700°C by using ethylene as precursor. The catalyst for all the samples were deposited by using spin coating method with speeds ranging from 500-1000 rpm. The functionalisation of the nanotubes was down by submersion of the substrate into aqueous solution of PVOH (99% hydrolyzed, MW-89-98K, obtained from Alfa Aesar), which was prepared by mixing PVOH with deionized water at the ratio 1:10000 (w/v) and heating at 90°C for 1 hour with constant stirring. The substrate was kept in the solution overnight, since the functionalisation of PVOH occurs while cooling. The substrates were then removed by rinsing with copious amount of deionized water and drying under vacuum.
To study the effect on the wettability of the carbon nanotubes by PVOH functionalisation, dynamic contact angles were measured by using contact angle analyzer. The contact angles of the functionalized CNTs were compared with that of the pristine carbon nanotubes. The electrical characterization was carried out by using probe station (Desert Cryogenics) coupled with semiconductor parameter analyzer (Agilent, 8146C). The IV characterization was conducted in vacuum conditions.
3. Results and Discussion
Figure 1 illustrates the SEM micrographs of multiwall carbon nanotubes before and after functionalisation with PVOH. It can be clearly seen that even a small amount (0.001 % w/v) of PVOH can significantly change the surface morphology of the nanotubes. In Figure 2 the effect on the water droplet deposited on the multiwall nanotubes before and after functionalisation is shown. The dynamic contact angles (advancing and receding) were measured for both single wall and multiwall carbon nanotubes. In Table 1 it can be seen that there is change in contact angle from 148 to 24 (advancing angle) corresponding to an average of 84% decrease when carbon nanotubes are functionalized. This clearly suggests that PVOH can be used for modifying the hydrophobic behavior of nanotubes to highly hydrophilic. The basic mechanism of interaction between the PVOH and nanotubes can be attributed to the lowering of interfacial free energy which is evident from the change in the contact angles of the functionalized nanotubes. PVOH tends to crystallize and introduce an alcohol functional group on the surface of the nanotubes. These functional groups can further act as intermediate for linking with various molecules which are to be sensed.
Figure 1: Multiwall carbon nanotubes without functionalisation (Left) and with PVOH functionalisation (Right)
Figure 2: Effect on the water droplet deposited on the multiwall carbon nanotubes before (left) and after (right). (Size of each sample: 1 cm2)
Table 1: Effect of PVOH functionalisation on single wall and multiwall carbon nanotubes
Advancing Angle / Receding AngleSWNT (Before Functionalisation) / 139.8 / 121
SWNT (After Functionalisation) / 25.6 / 18.2
MWNT 1 (Before Functionalisation) / 147.8 / 133.8
MWNT 1 (After Functionalisation) / 23.6 / 19
MWNT 2 (Before Functionalisation) / 148.2 / 139.8
MWNT 2 (After Functionalisation) / 34 / 25.2
SWNT: Single Wall NanoTube
MWNT: Multi Wall NanoTube
0.001% w/v of PVOH in distilled water
4. Conclusion
In this study single wall and multiwall carbon nanotubes were functionalized by using PVOH. It was shown that PVOH is able to modify the surface behavior of single or multiwall carbon nanotube from hydrophobic to highly hydrophilic. These findings are being further studied for possible use of functionalized carbon nanotubes for humidity, gas and bimolecular sensing. The IV characterization is also being studied to understand the charge transport mechanism in these modified carbon nanotubes.
5. References
Choi, Y.C., Choi, W., (2004) “Growth of Y junction single wall carbon nanotubes”, submitted to Advanced Materials.
Choi, W.B., Cheong, B.H., Kim, J.J., Ju, J., Bae, E., Chung, G., (2003), “Selective growth of carbon nanotube for nano-scale transistor”, Advanced Functional Materials, Vol. 13, pp 80.
Li, J., Lu, Y., Ye, Q., Cinke, M., Han, J. and Meyyappan, M., (2003). “ Carbon nanotube sensors for gas and organic vapor detection”, NanoLetters , Vol. 3, 7, pp 929-933
Qi, P., Vermesh, O., Grecu, M., Javey, A., Wang, Q. and Dai, H., (2000). “Towards large arrays of multiplexed functionalized carbon nanotube sensors for highly selective and sensitive molecular detection” NanoLetters, Vol. 3, No. 3, pp 347-351
Dharap, P., Li, Z., Nagarajaiah, S. and Barrera, E. V., (2004). “Nanotube film based on single wall carbon nanotubes for strain sensing”, Nanotechnology, Vol. 15, pp 379-382
Kozlov, M., Moon, S.I., Smith, T.A., McCarthy, (2003), “Adsorption and chemistry of ultra –thin films of polyvinyl alcohol for sensor development”. Polymer, Vol. 44, No.2, pp 283.
Penza, M., Anisimkin, V.I., (1999), “Surface acoustic wave humidity sensor using polyvinyl alcohol film”, Sensors and Actuator, Vol. 76, pp 162-166
The Conference Proceedings will be produced directly from the camera-ready manuscripts received from authors. Our goal is to obtain, as closely as possible, the same appearance for all papersTherefore the authors should try to produce their paper, as closely as possible to this model paper.
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1.1 Margins (Second Heading: Times New Roman Font, Size 11pt, Title Case, Bold Face)
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1.1 These instructions have been prepared in the preferred format. You should prepare your paper as closely as possible to this example.
The margins should be set as shown in the following sections.
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1.1.1 Letter size paperPaper size (Third Heading: Times New Roman Font, Size 11 pt, First Letter Captial, Bold face)
Paper size: 8.5 inch x 11 inch.
Top: 0.75 inch., Bottom: 1 inch, Left: 1 inch, Right: 1 inch
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1.1.2 A4 size paperFinal text area
Paper size: 8.27 inch x 11.69 inch
Top: 0.75 inch., Bottom: 1.69 inch, Left: 0.77 inch, Right: 1 inch
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For these and any other paper sizes, theThe final text area must be 6.5 inch x 9.25 inch.
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1.2 Font
1.2 1 line The final page size for the Proceedings is A4 (217.2 x 29.710. cm2 inches) (182.9mm x 259.1mm). The text area will be 6.3 x 9.5 inches (16 cm x 24.2 cm). The top margin is 1.5 inches (38.1 mm)3 cm with the bottom and side margins at 1 inch 2.5 cm(25.4mm) each. Figure 1 shows these final dimensions.
Arial font (or a similar sans serif font) should be used for the title and headings. Times New Roman font with Single Spacing (or a similar serif font) should be used for the body text of tentirehe manuscript. Font sizes/formats should be as follows:
Title of Paper: Arial, 14pt, Bold FaceTimes New Roman Font, Size 142pt, All CapTitle Case, Bold Face, Center,
Author Name: Times New Roman, 111 0pt, Center, Title Case
Author Affiliations (Position, University or Company, City, State, Country): Times New Roman, 11 pt, Center, Italic, Title Case
1 line between body text paragraphs
First Heading:
Times New Roman, 12 pt, Title Case, Bold face
Second Heading: Times New Roman, 11 pt, Title Case, Bold face
Third Heading: Times New Roman, 11 pt, First letter capital, Bold Italic face
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Section Headings: Times New RomanArial, 112pt, All Cap, Bold Face