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 Luleå University of Technology

This project is conducted in High Pressure Spectroscopy Laboratory (Materials Physics group) Supervisor: Professor Alexander Soldatov 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 High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

Carbon Nanotube (CNT) Graphene layer roll-up 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 High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

Types of carbon nanotubes  Single-wall CNT → only one atomic layer in radial direction Single-wall CNT - 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 Double-wall CNT - 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 Multi-wall CNT - Always electrically conductive (metallic behavior) - Entangled - Much bigger diameters than SWNTs High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

Physical properties 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 Individual or CNT films or Silver Copper bundled CNTs fibres El. 10 4 - 10 5 Conductivity 10 6 59.6 × 10 6 63.01 × 10 6 [S/m] SWNT MWNT Carbon Silver Copper fibres Thermal conductivity 6600 3000 8 - 1100 419 401 [W/mK] High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

Resonance Raman Spectroscopy G - band Radial breathing mode (RBM) A High pressure spectroscopy lab    Division of Physics,TFM B CNT diameter: Luleå University of Technology RBM d t

Composites The Main idea: combine good properties of two or more materials. Composite Matrix (Metal, Ceramic, polymer) Filler material (particles, fibers etc) 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. High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

Composites 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. In situ polymerization has been done with CNTs in the polymer matrix CNTs in our composite: three-step chemical approach to functionalize SWNTs (performed at Henri Pointcaré Univeristy, Nancy) 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 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) 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) We have investigated the PMMA composites with CNTs concentrations: 0,013wt%, 0,023wt%, 0,032wt%, 0,048wt%, 0,08wt%, 0,097wt%and 0,6wt%. High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

Results Distribution of CNTs in the composite laser laser laser laser Raman spectrum at every scanning point Sample surface High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

Results Distribution of CNTs in the composite laser laser laser laser The Cluster Sample surface High pressure spectroscopy lab Division of Physics,TFM The Matrix Luleå University of Technology

Raman spectra of composite and source materials C N T C luster Normalized to highest peak Intensity (a.u.) 450 Interphase 400 M atrix P M M A 350 300 250 200 150 100 50 0 0 10 00 20 00 -1 ) R am an shift (rel. cm High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

Distribution of CNTs in the composite a) b) c) d) e) 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 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. G Shift gives information about: Pressure on CNTs → (upshift) Tensile stress of CNTs → (downshift) Temperature of CNTs → (downshift) Intensity proportional to CNT concentration - 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. 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. High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

FIB polishing for AFM experiments Polishing of surface for AFM studies a b ) ) Pt SEM – images untreated FIB polished untreated surface surface surface 300 nm 835 nm 13.5 ± 0.3 μ m AFM image High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

AFM experiment Crossection Image AFM image White dot diameters: 10 – 40nm 20 nm 10nm 19nm 19nm 22nm 19 nm SEM image Height view 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. 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) High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology

Collaboration/Acknowledgements International Graduate School “PhD Polis “ (TFN LTU) in collaboration with Prof. Edward McRae and Prof. Brigitte Vigolo Carbon Materials group, Nancy University : Associate Prof. Nils Almqvist (AFM experiments) Andreas Müller, former group member (now at MPI Stuttgart) Guillaume Chevennement (EEIGM project student) High pressure spectroscopy lab Division of Physics,TFM Luleå University of Technology