Synthesis of MWNTs, DWNTs and SWNTs Buckypaper using Triton x-100.

And comparing their mechanical ,electrical and physical properties (report submitted in (partial) fulfilment of the requirements for the completion ofChem991)

by

Awad Nasser Albalwi

School of Chemistry

University of Wollongong

2

Table of Contents Page.N0#

COVER

CONTENTS 2-3

ABSTRACT 4

1 Introduction 4

1.1 Carbon Nanotubes & bukypaper 4-5

1.2 Carbon Nanotube Synthesis 6

1.2.1 Arc-discharge and laser ablation methods: 6

1.2.2 Chemical Vapor Deposition 7

1.3 Applications of Carbon Nanotubes 8

1.3.1 Electronic 8

1.3.2 Energy 9

1.3.3 Sensors 9

1.4 Aim 11

2.0 Experimental: 12

2.1 Solution Preparation 12

2.2 Characterisation of the Solution 13

2.3 Preparation of buckypaper 13

2.4 Characterisation of the Buckypaper 14

2.4.1 Conductivity 14

2.4.2 Mechanical Testing 15

3

2.4.3 Scanning Electron Microscopy 16

3.0 RESULTS AND DISCUSSION 16

3.1 An effect of sonication time on the Dispersion Stability

& Microscopy Testing

16

3.2 Absorbance Analysis

20

3.3 Conductivity Analysis 20

3.4 Mechanical Analysis 23

3.5 SEM Images Analysis 24

4 Conclusions 28

5 Acknowledgements 28

6 REFERENCES 29

4

Abstract

In this study buckypaper of MWNTs, DWNTs and SWNT have been

synthesised using filtration of carbon nanotubes dispersed in 1% TritonX 100

as solvents. Dispersions were generated by pulse sonication of each single

wall carbon nanotubes (SWNTs) , Double wall carbon nanotubes (DWNTs)

and Multi wall carbon nanotubes in TritonX solvent. Fist, sonication times

were investigated for these CNTs to determine the optimum conditions for

generating stable dispersions of carbon nanotubes. It was found that optimal

dispersions could be generated using Trion X-100 solvent with all these

carbon nanotube by using 30minute periods of pulse sonication. The Three

buckypapers of MWNTs, DWNTs and SWNTs were produced by filtering

dispersions of carbon nanotubes which had undergone 30 minutes of pulse

sonication in TritonX100. Conductivity and measurements of the three

buckypaper (SWNT,DWNT&MWNT) samples yielded average values of 14.24

, 23 and 19 Scm-1 respectively. Mechanical measurements were determined

successfully . Homogeneity in the produced buckypapers were investigated

confirming by scanning electron microscopy .

1. Introduction

1.1 Carbon Nanotube & bukypaper

Carbon nano tube has acted as a front runner for the whole field of

nanotechnology, attracting much attention from the industries and

academic community. Carbon nanotubes actually emerge as the leading

material in the nanotechnology revolution. The unique morphology, dimensions

and defects of Carbon nanotubes are distinguished from the other carbon

forms.

5

There are essentially two categories of nanotubes that are prevalently used

today. The multiwall carbon nanotubes (MWNTs), that were catalytically

grown (by chemical vapor deposition; CVD). The dimensions of these were

typically several tens of nanometers in diameter, but occasionally smaller

structures including single-layer tubular structures were also observed. In

recent times they have shown the most promising appearance to the

commercial marketplace [8]. The single-wall nanotubes (SWNTs) in 199ed3

was prducby the NEC and IBM groups also by catalytic vapor deposition to

make single-layer tubular structures of graphene with diameters as small as

1 nm.

Fig.1 CNTs structures for SWNTs,DWNTs and MWNTs 6.

Buckypapers

Nanotubes have high tendency towards self aggregation due to strong Van

der waals forces. This property makes entanglement and aggregation of

nanotube easy. Entangled assemblies of carbon nano tubes that are prepared

by dispersion in solution and filtration with the help of ultrasonication are

called buckypaper. This assembly makes the handling of nanotubes easier for

dopping or raman spetrocopy.Potential applications of buckypaper include ,

SWNTs,One cylinder d = 0.4 – 3 nm DWNTs,Two cylinders d = 2.3 – 3.3 nm

MWNTs,Multiple cylinders d = 1.4 – 100 nm

6

radio frequency filtter,actuators, cold field emission cathode, Li-ion

batteries,solar cell.[8,9]

1.2 Carbon Nanotube Synthesis

CNTs have been synthesised in a wide variety of ways to varying yields and

degrees of purity. Nanotube have been synthesised by conducted by arc

discharge using graphite electrode carbon sources , Chemical Vapour

Deposition (CVD), LASER ablation, vapour-liquid-solid synthesis and the High

pressure carbon monoxide disproportionation (HiPCO) process3.

1.2.1 :Arc-discharge and laser ablation methods:

Both Arc-discharge and laser ablation methods involve the condensation of

carbon atoms generated from evaporation of solid carbon .The temperatures

using in this method ate close to the melting Temperature of the graphite

which between 3000-4000C.In the Arc-discharge method , carbons atoms

are evaporated using plasma of helium gas ignited by high currents pass

through opposing carbon anode and cathode . Arc-discharge has been

developed into method producing both high quality multi-wall nanotube and

single –wall nanotube .MWNT can be made by controlling the growth

conditions such as the pressure of inert gas in the discharge champer and

the arcing current.for as grown material , there are few defects such as

pentagons or heptagons existing on the sidewalls of the

nanotubes.Purification of MWNT can be achieved by heating the grown

material in an oxygen to oxidize away the graphitic particles.

For the growth of single-walled tube, a metal catalyst is needed in the arc-

discharge system. It was used a carbon anode conaining a small percentage

7

of cobalt catalyst in the discharge experiment, and found aSWNTs

generated in the soot material.

The method utilized intens laser pulses to ablate a carbon target containing

0.5 atomic percent of Ni and Co.The target was placed in the atube-furnace

heated to 1200C. During laser ablation , aflow of inert gas was pass through

the growth chamber to carry the grown NTs downstream to be collected on

a cold finger.

1.2.2:Chemical Vapor Deposition:

Chemical Vapor Deposition (CVD) methods have been successful in making

CNTs. The growth process onvolves heating acatalyst material to high

temperatures in a tube furnace and flowing a hydrochabon gas through the

tube reactor for a period of time . materials grown over the catalyst are

then collected .

8

1.3:Applications of Carbon Nanotubes

After a decade and a half of research efforts, these tiny quasione-

dimensional structures show great promise for a variety of applications

areas, such as nanoprobes, molecular reinforcements in composites, displays,

sensors, energy-storage media, and molecular electronic devices.

1.3.1:Electronic

SWNTs have emerged as adependable class of electronic material due to

their nano scale dimentions and good electronic conduction. They have

recently been used to make all of the conducting (i.e., source, drain, and gate

electrodes) and semiconducting layers, respectively, of a transparent,

mechanically flexible, hin-film transistor (TFT). These devices are

fabricated on plastic substrates using layer-by-layer transfer printing of

SWNT networks grown using optimized chemical vapor deposition (CVD)

procedures. The good adhesion ond performance on plastic of SWNT that

would be difficult, or impossible, to achieve with conventional material,

.makes it a good materialin electronic network and and thermal transmission.

There have been several reports pointing out the record axial thermal

conductivity of individual nanotubes. Efficient cooling can be achieved on

silicon chips using aligned carbon nanotube arrays (MWNTs). [7]

9

1.3.2:Energy

Carbon nanotubes have been adopted as the preferred alternative electrode

material instead of conventional carbon materials have been utilized either

as the electrode materials carbon.

This is because carbon nanotube have unique electrical and electronic

properties, a wide electrochemical-stability window, and a highly accessible

surface area. They have been used in supercapacitors, Li-ion batteries, solar

cells, fuel cells and other energy applications. [7,8]

1.3.3:Sensors

Carbon nanotubes have been used as sensing elements utilizing their

electrical, electrochemical and optical propertie. SWNTs have been used to

detect low concentration of toxic gases which is important for environmental

purposes and chemical safety. SWNTs have been used as gas-sensing

elements due to the 1-dimensional electronic structure with all the atoms

residing only on the surface. Carbon nanotube have advantages over

conventional metal-oxide-based sensors in terms of power consumption,

sensitivity, miniaturization, and reliable mass production . SWNT gas sensor,

had an arrangement based on a field-effect transistor (FET). The

conductance change of a back-gated SWNT channel upon analyte adsorption

is monitored via source/drain electrodes.

There are large numbers of electrochemical sensors utilizing CNTs. In the

DNA-hybridization, DNA is covalently attached to MWNTs on a gold

substrate. After hybridization, either methylene blue or ferrocine can be

used to induce a current change.

In optical sensor, the fluorescence of noncovalently functionalized SWNTs

is exploited for biological detection. Binding of the analyte to the

10

immobilized target results in a SWNT surface event that modulates the

SWNT fluorescence. While in the glucose-detection system, the

fluorescence intensity is also modulated In the DNA hybridization and

metal-cation detection systems, the fluorescence maxima gets shifted in

wavelength Electron charge transfer between a SWNT and an adsorbed

analyte was shown to occur both theoretically and experimentally.. Carbon

nanotubes are good materials for use as electrodes in electrochemical

sensors due to fast electron-transfer kinetics from a number of

electroactive species. A great and wide range of sensor types have been

developed from carbon-nanotube paste electrodes (CNTPE), glassy carbon

electrodes (GCE) modified by CNTs, metal nanoparticle-modified CNT

electrodes, to CNTs embedded in a conducting polymer matrix. A great

number ofsensors involve immobilizing enzymes at the CNT electrode,

either through electrostatic forces or through covalent attachment. In

electrochemical biosensor development, glucose sensor provided a major

thrust in early progres of sensing technologies. A great number of

electrochemical glucose sensors utilize the enzyme glucose oxidase (GOx),

which catalyzes the oxidation of β-D-glucose to D-glucono-1,5- lactone with

hydrogen peroxide (H2O2) as a reaction byproduct. The generated H2O2 is

then oxidized at the electrode and detected by measuring current flow.

Multiwall carbon nanotubes (MWNTs) grown directly on a Pt electrode with

GOx (glucose biosensor) have been fabricated . The device was fabricated

by adsorbing GOx to carboxylic acid groups functionalized to the MWNTs.

MWNTs have been encapsulted in a Teflon matrix along with GOx on a GCE,

and demonstrated a marked increase in sensitivity of glucose detection

compared to an analogous device made with graphite. MWNTs and GOx have

11

been embe dded in a conducting matrix of polypyrrole and showed a roughly

linear response to glucose in the range of 0–20mM. A different method have

been employed by incorporating Pt nanoparticles in a Nafion/GOx/MWNT

electrode.. Lower sensitivity was obtained when Pt nanoparticles was

extended to SWNT and Nafion/GOx/SWNT composite on a GCE gave a

sensitivity of 0.5 μM. In electrochemical detection of DNA. Single-stranded

DNA (ssDNA) is immobilized on the electrode and current changes are

monitored upon DNA hybridization with a complementary strand. Usually, a

redox indicator that has higher affinity for double-stranded DNA (dsDNA)

is used to change the electrochemical response. Sheets of MWNTs and

SWNTs electromechanical actuators have been proposed using. Nanotube

sheets infiltrated with polymer binders have been shown to perform as

excellent electrochemical actuators, mimicking the actuator mechanism

present in natural muscles. The actuators made from carbon nanotubes have

better mechanical strength and are superior to conducting polymer-based

devices, since in the former no ion intercalation (which limits actuator life) is

required. Some of the applications bon nanotubes actuator includes

nanotube-based microcantilevers and artificial muscles that are stable at

high temperatures. sheets of MWNTs and SWNTs sheets of MWNTs and

SWNTs. [7,8]

1.4 Aims

The aims of this project are to:

Investigate of the solubility of CNTs ((SWNTs, MWNTS & DWNTS)

by using the organic solvent (TritonX-100) .

Investigate the effect of a variety of sonication time on the stability

of the aforementioned dispersions.

12

Characterise the produced organic solvent dispersions, using

microscopy and UV-Vis spectrophotometry.

Synthesise buckypaper membranes (SWNTs, MWNTS & DWNTS)

using dispersions made from TritonX-100 solvent.

Characterise the produced buckypapers (SWNTs, MWNTS &

DWNTS) and comparing them with each other in terms of their

mechanical, electrical and othier physical properties.

2:Experimental:

2.1 Solution Preparation

In this mini project , It was generated 3 dispersions which every each

contained one type of CNTs and organic solvent. First, by using

manufactured MWNTs , 15mg was weighted in the sonication vessel by using

a analytical balance. The required weight (1%=0.15gm) of solvent (triton-

X100) was then measured in 50ml beaker using also analytical balance and

then 15 ml Milli-Q water was added and the mixture was stirring for around

10mins. The solvent was transferred into the sonication vessel. The mixture

of MWNTs and the solvent was dispersion by using pulse sonication using a

Branson ultrasonics horn, Sonications periods were 1,2,5,10,20,30,45 and 60

minutes where the sonication time is given as the ‘on’ time for the sonication

probe, which pulse duration of 0.5 & following by 0.5 second pulse delay. The

sonication vessel was cooling in ice path during the sonication process.

the measuring of the UV-Vis was measured at every certain time above

between 1000-300nm. The process above was repeated by using different

CNTs which were SWNTs and DWNTs. The SWNTs & DWNTs were

prepared via other two groups involving in this work.

13

2.2 Characterisation of the Solution

Solution characterisation was conducted both by qualitative observation and

Ultraviolet-Visible (UV-Vis) spectrophotometric characterisation using a

Cary 500 Scan Uv-Vis-NIR spectrophotometer. For UV-Vis characterisation

a known volume of MWNTs dispersion (1000µml) was transferred to a 1cm

quartz cuvette using an air displacement pipette. These solutions were then

diluted by pipetting 1.9ml of Milli-Q -water and then mixed. The reason for

diluting the sample was to make sure that the measured absorbances were

within the rang of the UV instrument1. This process was repeated at each

certain time mentioned above . The sample absorbance was measured

between 300 and 1000nm and was calibrated for the absorbance of a sample

of the solvent. By using excel program , the absorption of sample vs the

various time at 600nm was plotted. And then the suitable time for suitable

dispersion was determined from the curve.

2.3 Preparation of buckypaper

MWNTs ,15mg was weighed in the sonication vessel by using a analytical

balance. The required weight (1%=0.15gm) of solvent (triton-X100) was then

measured in 50ml beaker using a analytical balance and then 15 ml Milli-Q

water was added and the mixture was stirring for around 10mins . The

solvent was transferred into the sonication vessel. The mixture of MWNTs

and the solvent was dispersion by using pulse sonication for 30minuts.the

other such dispersion was prepared for buckypaper . The two MWNTs

dispersion solutions were combined and transferred into 300ml beaker and

then diluted by 250ml Milli-Q water. The two such dispersions were

required for each buckypaper, producing a total MWNT loading of 30mg per

paper. These combined dispersions were filtered through commercial

14

membrane filter paper housed in an Aldrich glass filtration. by using a

Vacuum Pump, The buckypapers were washed by Milli-Q water and then

dried . The buckypapers was left for around 6 days after filtration .

The same process above e was done for preparing SWNTs and DWNTs

bucky papers from other two groups.

2.4 Characterisation of the Buckypaper

As prepared buckypapers were characterised using mechanical, physical and

electrical testing procedures. Typically the three produced buckypaper

(MWNTs , DWNTs and SWNTs) membranes were cut to different sizes

using a surgical scalpel and ruler, generating triplicate samples for

measurement by a variety of methods as specified below.

The thickness of prepared buckypapers were measured using digital

micrometer . Measurements of the length and the width were done using

normal ruler.

2.4.1 Conductivity measurments

Buckypaper samples of MWCNs 3.2mm width and and 0.085µm thick were

used for conductivity measuring . each end of the buckypaper sample was

connected to copper tape using high conductivity silver paint . This was then

mounted on to an insulating glass slide and the two paces of copper tape

were attached to the positive and negative electrodes of an Agilent

Arbitrary Waveform Generator . Current and Voltage characteristics were

investigated by delivering a known voltage across samples of various lengths

using a triangular wave function oscillating between ±0.01V. The current

flowing in the system was measured as a function of time using an Agilent

Digital Multimeter. By using a surgical scalpel , the buckypaper was

15

shortened After each measurement. Electrical contact was re-established

between the buckypaper and copper tape by reapplying of silver paint to the

buckypaper/copper tape interface (fig.2.1). The procedure above was

repeated for measuring the conductivity of SWNTs and DWNTs from other

groups.

Figure 2.1: the conductivity measurement system.

2.4.2 mechanical properties

The mechanical properties of buckypaper membranes were tested using an

Instron 5566 tensile tester (fig4.2). Buckypaper samples measuring at

different width x 10mm length were clamped between two parallel plates. A

constant extension rate of 0.1 mm/min was then applied to the system until

sample failure with the required mechanical stress and strain being

recorded at the same time. This testing was used to determine the Young’s

modulus, strength and ductility of the buckypaper samples.

16

Fig. 4.2.Tensile machine system INSTRON Model 5566

2.4.3Scanning Electron Microscopy (SEM)

SEM images of buckypaper materials were obtained using SEM located at

innovation campus of the University of Wollongong. The SEM images

provided by Dr Stephen Ralph and Luke Sweetman.

3 Results & Discussion

3.1 An effect of sonication time on the Dispersion Stability of

SWNTs,DWNTs and MWNTs using Triton X-100 .

In this work, an effect of sonication time on the dispersion of three type of

CNTs in 1% (w/v) triton X-100 solution was investigated using the absorption

spectrophotometry at several time period. The aim of this investigation , to

measure the suitable time required to prepare efficiency CNTs solution

using sonication method. It was noted that in every individual sonication

mixtures of SWNT-TritonX-100 ,DWNTs-TritonX-100 and MWNT-

TritonX-100 were observed to progressively darken colour from transparent

to jet black with increase the period time up to (1h) (fig.3.1 ). The changes

17

in the mixtures colour resulting from the aggregates of CNTs at the base of

the solution were reduced during the sonication procedure.

Fig 3.1: The changes in the mixtures colour during ultrasonication4.

Fig. 3.2,3.3&3.4, have shown the effect of increasing sonication time on the

absorption spectrum of a samples containing SWNT-TritonX-100 ,DWNTs-TritonX-100

and MWNT-TritonX-100 . It can be said that the observed absorption bands were

resulting from separation of practicals of SWNTs,DWNTs and MWNTs in the

solutions. An increase of the sonication time led to in both greater overall

absorbance, and the bands indicated that van Hove singularity becoming

noticeable1.

The inserted Fig.1,2&3 have shown the effect of sonication time on the absoption

at 600nm. All three figures have shown clearly that the absorbance was increasing

rapidly at the first fifteen minutes and then slightly arising until around thirty

minutes . The differences between the absorbance values between 30 and 60

minutes were not significantly effective on the sonication time. For this reason, it

was determined 30 minutes as favourite sonication time for synthesis bukypaper

from MWNTs, DWNTs and SWNTs which agreed with other researchers1 .

transparent Jet black

18

Fig. 3.2 Effect of increasing sonication time on the UV-visible absorption

spectrum of a dispersion containing 0.1% (w/v) SWNT and 1% (w/v) Triton

X-100. The inset shows how the absorbance at 600 nm varied in response to

changes in sonication time. All samples were measured after being diluted

20times using Milli-Q water.

Fig. 3.3 Effect of increasing sonication time on the UV-visible absorption

spectrum of a dispersion containing 0.1% (w/v) DWNT and 1% (w/v) Triton

X-100. The inset shows how the absorbance at 600 nm varied in response to

changes in sonication time. All samples were measured after being diluted

20times using Milli-Q water.

19

Fig. 3.4 Effect of increasing sonication time on the UV-visible absorption

spectrum of a dispersion containing 0.1% (w/v) MWNT and 1% (w/v) Triton

X-100. The inset shows how the absorbance at 600 nm varied in response to

changes in sonication time. All samples were measured after being diluted

20times using Milli-Q water.

Microscopy Testing

Images.3.1,3.2&3.3 have shown the optical microscopy of the SWNT–Triton

X-100, DWNT–Triton X-100 and MWNT–Triton X-100 dispersions obtained

after 60 min sonication time . Three images have indicated clearly there

were no significant aggregates present in these solutions.

Image3.1.MWNT-Triton X-100 dispersion Image3.2.DWNT-Triton X-100 dispersion

Image3.3.SWNT-Triton X-100 dispersion

20

3.2 Absorbance Analysis

Comparisons of an effect of (1%)Triton X-100 on production SWNT ,

DWNTs and MWNT despersions were done by comparing the absorbances of

dispersions containing equivalent loadings of (0.15gm)Triton X-100 in 15ml

Milli-Q water & 1% from each CNTs at 30 minuets dispersions time

(Fig.3.5). The MWNTe was found to be the high readily able to dispersion in

Triton X-100. The DWNT and SWNT were nearly the same in their ability in

dispersing in Triton X-100.

Figure3.5 : Effect of Triton X-100 on the production of SWNT,DWNT &

MWNT dispersions.

3.3 Conductivity analysis:

The conductivity of SWNTs,DWNTs& MWNTs buckypaper samples was

measured by comparing the resistance of buckypaper samples of varying

lengths. A linear relationship between current and voltage in the application

of Ohm’s Law. All bukypaper samples showed current/voltage data with good

agreement to their respective linear squares regressions R2 .(Fig.3.6).

21

Figure3.6 : Current-Voltage characteristics for a buckypaper prepared from

SWNTs, DWNTs & MWNTs in triton-100 dispersions.

As reported by Boge et al1., the total resistance (Rt) can be :

Rt = L (Aσ) -1 + Rc,

where L is the length of the buckypaper(in cm), A is its cross sectional area

(in cm2), σ is the bulk conductivity and Rc is the contact resistance ((in Ω).).

As the contact resistance is constant for all sample lengths a plot of total

resistance vs. sample length will give a slope of A-1σ -1.

The conductivity (σ), in (in S cm-1), is then given by

σ = 1/(m *A)

SWNT DWNT

MWNT

22

where m is the slope of a plot of resistance vs.sample length (fig.3.7)

Table 3.1 : Conductivities of the three buckypaper samples produced from

SWNTs, DWNTs & MWNTs dispersed in tritonX-100.

Bucky paper SWNTs DWNTs MWNTs

Conductivity (Scm-1) 14.24

22.98

18.9

The table3.1 has shown that the DWNT has the highest conductivity

following by MWNT. The SWNT was 38% less conductivity than DWNT.

Fig3.7: The correlation between electrical resistance and changing the

length of a strip of buckypaper prepared from SWNT-TritonX-100

,DWNTs-TritonX-100 and MWNT-TritonX-100.

23

3.5 Mechanical Analysis

The most important characteristics of buckypaper is the mechanical

properties dut to their roles in determining their applications1.

Stress-strain relationships were evaluated for each of the three buckypaper

samples to determine their mechanical properties (Fig.3.8 ). MWNT , DWNT

and SWNT Buckypapers were observed to undergo elastic deformation

during the initial stretching, producing a linear stress-strain region from

which the Young’s Modulus (E) was calculated using,

E = σ ε-1,

where, σ is the tensile stress applied to the material, and ε is the tensile

strain of the material.

Table 2. Strength , strain at highest point and YOUNG'S MODULUS for

bukypapers prepared from SWNT-TritonX-100 ,DWNTs-TritonX-100 and

MWNT-TritonX-100.

TENSILE

STRENGTH

Mpa

%STRAIN

YOUNG'S

MODULUS

MWNT 2.55±0.27 2.84±0.57 224.12±22

DWNT 0.77 0.43 31.67

SWNT 2.21±0.44 2.08±0.58 209±49

MWNT

SWNT

DWNT

24

Fig .3.8 Stress-strain curves for bukypapers made from buckypapers

prepared from SWNT-TritonX-100 ,DWNTs-TritonX-100 and MWNT-

TritonX-100.

The stretching was observed to give inelastic nature of the buckypaper, and

extensions generated in this region being unrecoverable after the release of

stress. Finally, after sufficient extension, failure of the buckypapers were

determined. The materials tensile strength and strain were determined from

this point as in table .3.2 .

Table3.2 & fig3.8 have shown significant variations in mechanical properties

were observed between DWNT bukypaper and the other two CNTs. The

Table .3.2 clearly indicated that There was no big differences in Tesile

strength , strain and Young’s modules of bukypapers prepared from SWNT-

TritonX-100 and MWNT-TritonX-100 suggesting both them have slightly

same mechanical properties. On other hand , there was great differences

between them and bukypaper prepared from DWNTs-TritonX-100 . The

Table has illustrated that the Tesile strength , strain of bukypaper prepared

from MWNT were greater by 70% and 85% respectively than bukypaper

prepared from DWNTs. From above , it can be said that DWNT bukypaper

has poor mechanical properties in contrast to MWNTs & SWNTs.

3.6SEM images:

Fig 3.9 have shown that there were a significants in the surfaces of buky

papers prepared from SWNT-TritonX-100 ,DWNTs-TritonX-100 and MWNT-

TritonX-100. Fig S2,D1 & M2 have indicated clearly that there were some

regions that appeared to containing some aggregates of SWNT , DWNT and

MWNT. The Images 20,000X have indicated that the DWNT bukypaper has

significant large bundling of CNTs ( imag.D1) in contrast with the same

25

magnification of SME images of SNWT & MWNT (imag.S1&M3) . In addition

, the Image.M3 has shown there was few bundling of MWNT but larger than

the bundling of SWNT ( image.S1). Image.S1 has shown a lot of very small

aggregates of SWNT.

a hundred thousand times magnification SEM images resolved nanotube

ropes corresponding to the bundling of only a few SWNTs (image.S1) , one

large bundling of DWNTs (image.D3) and two bundling of

MWNT(image.M2).imageM3 has shown clearly there was no bundling of

CNTs which provide signs of high quality of the sonication procedure. the

bundling of CNTs in our bukypapers might be minimized by increasing

sonication time . The CNTs rope lengths were visualised indicating that the

rope lengths is longer in MWNT than DWNT and SWNT.

26

SEM imaging - 1/SWNT

2/DWNT

S1 S2

S3

D1 D2

DWNT

aggregates

SWNT

aggregates

SWNT raps

27

3/ MWNT

Figure 3.9: SEM images of a CNT buckypaper produced from SWNT-

TritonX-100 ,DWNTs-TritonX-100 and MWNT-TritonX-100.

M1

D3

M2

M3

MWNT

aggregates

28

4:Conclusions :

In this project bukypaper of MWNTs, DWNTs and SWNT were successfully

disperse using Triton X-100 as a solvent . The suitable dispersions time of

all these CNTs was around 30minuts which confirmed by UV-Vis absorbance

measurements at several amount of times .The Young’s modulus ,tensile

strengths and strain were extremely high in MWNTs and SWNTs

bukypapers than DWNTs . DWNTs bukypaper was very brittle and it was

easy to break making some difficulties to measure its mechanical

properties. The SEM images confirmed that the DWNT has big bundling

which might be the reason for its poor mechanical properties This can be

avoided by increasing the dispersions time in further works. SEM images of

the buckypaper of MWNT were highly homogeneous with very small amount

of aggregation, containing long ropes . Conductivities of the three

buckypaper samples produced from SWNTs, DWNTs & MWNTs dispersed in

tritonX-100 were low in SWNTs in contrast to MWNTs & DWNTs.

4.Acknowledgements

First of all I would like to thank Allah for his blessing and guidance without

which I couldn’t finish this report . I would like also to thank the University

of Wollongong, School of Chemistry for computational facilities , Academic

resources and on chemical materials & instruments facilities. I would also

like to thank Dr Stephen Ralph, subject coordinator (CHEM991) for his

guidance , support and motivation which was useful for doing this report .I

would also like thank Luke Sweetman (PhD Candidate) for helpful

discussions ,training on synthesis Bucky paper , using techniques in

determining of physical ,electrical and mechanicals properties and continuous

guidance, support and academics resources .Lastly but in no way the least I

would like to thank my family and friends for their continuous support

,prayers and love .

29

4. References

1Boge ,J et al ,2009The effect of preparation conditions and biopolymer dispersants on the

properties of SWNT buckypapers

2Dresselhaus,M.S & Dresselhaus ,G ,Avouris ,P ,2000. Carbon Nanotubes

Synthesis,structure,properties, and applications.New York

3 Sherrell P. (2007) ‘Novel Nanocomposite Electrodes for Energy Applications’ School of

Chemistry, Honours thesis, University of Wollongong

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