drs. wei tian & yanhui chen sep-dec. 2014. microscopic technique scanning electron microscope...
TRANSCRIPT
《 Modern Research Methods in Polymer
Science》Drs. Wei Tian & Yanhui Chen
Sep-Dec. 2014
Microscopic technique
Scanning Electron Microscope (SEM)
Transmission Electron Microscope (TEM)
Atomic Force Microscope (AFM)
Modern Research Methods in Polymer Science
Scanning Electron Microscope (SEM)
Scanning Electron Microscope (SEM)
Advantages
Simple preparation
Long depth of field
Wide view
High amplification factor
High resolution
Small damage
Comprehensive Analysis
Rapid data acquisition
Limitations
Solid samples
Coating (Au, Au-Pd, etc.)
Vacuum environment
Scanning Electron Microscope (SEM)
Application
1) Surface morphology
2) Crystal structure
3) Multi-phase structure
4) Acquiring elemental maps or spot chemical analyses using EDS (Energy-Dispersive X-Ray Spectroscopy)
5) Obtaining discrimination of phases based on mean atomic number (commonly related to relative density) using BSE (Back-scattered Electron Detector)
6) Getting compositional maps based on differences in trace element "activators" (typically transition metal and rare earth elements) using CL (cathodoluminescence)
Scanning Electron Microscope (SEM)
Description
Stegelmeier, C.; Filiz, V., et al. Macromolecules 2014, 47, 5566.
Transmission Electron Microscope (TEM)
Incident high-kV beam
Transmission Electron Microscope (TEM)
Imaging methods
Contrast formation Bright field Diffraction contrast
Electron energy loss Phase contrast Diffraction
Disadvantages
A relatively time consuming process with a low throughput of samples
Sample damage The field of view is relatively small
Sample preparation
Tissue sectioning Sample staining Mechanical milling
Chemical etching Ion etching Replication
Polymer crystalline
structure and morphology
Transmission Electron Microscope (TEM)
Application
Distribution and size of micropores
Polymer composition
Distribution of dispersed phase
lattice distortion
Examples
Transmission Electron Microscope (TEM)
GrapheneCarbon nanotube
PE/SWNT NHSK
Transmission Electron Microscope (TEM)
Pérez, R. A.; López, J. V., et al. Macromolecules 2014, 47, 3553.
Description
Atomic Force Microscope (AFM)
Contact mode Tapping mode Non contact mode
Atomic Force Microscope (AFM)
Contact mode
Non-contact Mode
Tapping mode
Lim
itat
ion
s
• Easily damage soft samples due to the adhesive force
• Low lateral resolution
• Low scanning rate• Only for water-
funk samples
• Low lateral force• Low scanning rate
compared to contact mode
Ad
van
tage
s • Fast scanning rate• Atomic resolution
image• Stiff samples with
Vertical changes
• No force is applied on the samples
• High resolution• No damage to the
samples
Atomic Force Microscope (AFM)
Surface topography and microphase separation
Identification of individual surface atoms
Polymerization process
Physical properties
Application
Atomic Force Microscope (AFM)
Description
Stegelmeier, C.; Filiz, V., et al. Macromolecules 2014, 47, 5566.
References
1. 田 威，孔 杰，胡思海 . 高聚物的现代研究方法 [M] ，西北工业大学出版社， 2014.
2. http://en.wikipedia.org/wiki/Scanning_electron_microscope
3. http://en.wikipedia.org/wiki/Transmission_electron_microscopy
4. http://en.wikipedia.org/wiki/Atomic_force_microscopy