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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Raman and AFM characterization of carbon nanotube polymer - - PowerPoint PPT Presentation
Raman and AFM characterization of carbon nanotube polymer - - PowerPoint PPT Presentation
Raman and AFM characterization of carbon nanotube polymer composites Illia Dobryden High pressure spectroscopy lab Division of Physics,TFM Lule University of Technology This project is conducted in High Pressure Spectroscopy Laboratory
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Outline
- Introduction
– General Introduction to carbon nanotubes. – Raman spectroscopy of CNTs. – Introduction to carbon nanotube composites. – Functionalization of carbon nanotubes.
- Marerials and methods
- Results
– Distribution of CNTs in the composite. – Interaction between CNTs and the composite matrix. – The qualitative estimation of CNTs amount in the polymer matrix. – FIB polishing and AFM experiments.
- Conclusions and Future Work
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Diameter: < 1 nm up to tens of nm
- Lenght: < 1 μm up to even several mm
- High aspect ratio (Lenght/diameter) up to > 10000
- Considered as „1D“ material
- Extraordinary mechanical, electrical, thermal properties
roll-up
Carbon Nanotube (CNT)
Graphene layer
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
- Single-wall CNT → only one atomic layer in radial direction
- Metallic and semi – conducting
- Tend to agglomerate in bundles
- Entangled
Double-wall CNT → two atomic layers in radial direction
- Good model system to study intertube interactions
- Pressure screening of inner tubes by outer tubes
- Reinforcement of outer tubes by inner tubes
- Much more resistant to high pressures
Multi-wall CNT→ several atomic layers in radial direction
- Always electrically conductive (metallic behavior)
- Entangled
- Much bigger diameters than SWNTs
Types of carbon nanotubes
Single-wall CNT Double-wall CNT Multi-wall CNT
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Property MWNT Carbon fibre Steel Kevlar Young‘s Modulus [Gpa] 1060 150 - 950 190 - 210 130 Tensile strenght [GPa] 63 4-7 0,5 - 2 3 - 4
Physical properties
Individual or bundled CNTs CNT films or fibres Silver Copper El. Conductivity [S/m] 106 104 - 105 59.6 × 106 63.01 × 106 SWNT MWNT Carbon fibres Silver Copper Thermal conductivity [W/mK] 6600 3000 8 - 1100 419 401
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Resonance Raman Spectroscopy
Radial breathing mode (RBM) G - band
B d A
t RBM
CNT diameter:
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Composites
CNTs are the good candidates as the filler material because they have great mechanical, electric properties. Possible problems in using CNTs as the filler material:
- 1. CNTs exist in bundle state.
- 2. Bad interaction between CNTs and the composite matrix.
- 3. It is difficult to get a good dispersion in the composite.
The Main idea: combine good properties of two or more materials.
Composite
Matrix (Metal, Ceramic, polymer) Filler material (particles, fibers etc)
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Possible Solutions:
- 1. - Good dispersion by ultrasonication.
- 2. - Functionalization of CNTs.
Main idea behind functionalization: Covalent attachment of molecules which will has a good link with the matrix material to CNT surface. CNTs in our composite: three-step chemical approach to functionalize SWNTs (performed at Henri Pointcaré Univeristy, Nancy) In situ polymerization has been done with CNTs in the polymer matrix
Composites
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Project motivation
Synthesis and Characterization of the new composite material based on functionalized carbon nanotubes
Raman spectroscopy → proved to give various information about CNT systems Atomic Force Microscopy (AFM) → For direct microstructural study
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Materials and Methods
Materials: - Arc-discharge three step functionalized CNTs (performed at Henri Pointcaré University, Nancy (France)
- PMMA (Polymethylmetacrylate)
We have investigated the PMMA composites with CNTs concentrations: 0,013wt%, 0,023wt%, 0,032wt%, 0,048wt%, 0,08wt%, 0,097wt%and 0,6wt%. Methods: - The Confocal Raman Spectroscopy
Raman spectrometer CRM-200,
- a green NdYVO4 diode laser (532 nm, 2,33 eV)
- a red He-Ne laser (633 nm, 1,96 eV )
- Focused Ion Beam (FIB)
- Atomic Force Microscopy (AFM)
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Results
Distribution of CNTs in the composite
Sample surface laser laser laser laser Raman spectrum at every scanning point
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Results
Distribution of CNTs in the composite
Sample surface laser laser laser laser
The Cluster The Matrix
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
10 00 20 00 50 100 150 200 250 300 350 400 450 C N T C luster Interphase M atrix P M M A R am an shift (rel. cm
- 1)
Normalized to highest peak Intensity (a.u.)
Raman spectra of composite and source materials
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Image : G+ - intensity maps for a) 0.013wt%, b) 0.023wt%, c) 0.048wt%, d) 0,097wt% and e) 0,6wt% CNT – PMMA composites, 2.33eV laser excitation
b) a) e) c) d)
Distribution of CNTs in the composite
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Interaction between CNTs and the composite matrix
The Idea:
- The good composite sample must has quite good interaction
between the filler material and the composite matrix.
- We expect that the CNT G-band shifts for Functionalized CNTs
(FCNTs) the polymer matrix comparing to pure FCNTs due to interaction between the matrix and FCNTs.
G Shift gives information about: Pressure on CNTs → (upshift) Tensile stress of CNTs → (downshift) Temperature of CNTs → (downshift) Intensity proportional to CNT concentration
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Dependence of the CNT G-band shift in the PMMA matrix vs CNT concentration
→ There is G UpShift on the graph. It indicates that the PMMA matrix applies pressure on FCNTs.
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
FIB polishing for AFM experiments
a ) b )
Pt
Polishing of surface for AFM studies
SEM – images
835 nm 300 nm 13.5 ±0.3 μm
untreated surface untreated surface FIB polished surface
AFM image
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
AFM experiment
Height view
19nm 19nm 22nm 10nm
Crossection Image White dot diameters: 10 – 40nm AFM image SEM image
20 nm 19 nm
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Conclusions
- Distribution of CNTs in PMMA composite is inhomogenious.
- There is an indication that the matrix molecules surrounding the
CNTs exert pressure on the nanotubes.
- The CNT bundle size in the polymer matrix is ~ 20 nm.
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology
Future work
- Further AFM experiments (nano-indentation) to determine mechanical
properties of the composites
- Spectroscopic study of thermal effects in CNT-PMMA composites
exposed to high power laser irradiation
- Increase of CNT dispersion in polymer matrix via purification of
functionalized CNT (from non-functionalized)
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High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology