drs. wei tian & yanhui chen sep-dec. 2014. microscopic technique scanning electron microscope...

《 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