Chapter 2.Chapter 2.Techniques for studying 

polymers

Characterization of Polymersy

Thermal analysis

Microscopy

SpectroscopySpectroscopy

Diffraction or scatteringDiffraction or scattering

Density measurement and etc…y

Thermal analysisy

-Thermal analysis for BULK samples

Differential scanning calorimeter (DSC)Differential thermal analysis (DTA)y ( )

Thermal gravimetric analysis (TGA)Thermal gravimetric analysis (TGA)

-Typical amount of sample for DSC: 1~10 mgTypical amount of sample for DSC: 1 10 mg

-Is it available in thin film analysis? Absolutely NOT

Microscopypy

Optical Microscopy

Scanning Electron Microscopy

Transmission Electron Microscopy

Scanning Prove Microscopy

Electron MicroscopyElectron Microscopy

• SEM – Secondary electron

imicroscopy

• TEMTransmission electron– Transmission electron microscopy

Acquiring surface image(Microscopy)

Scanning Electron Microscopy

Scanning Electron Microscopy (SEM)Scanning Electron Microscopy (SEM)

SEM vs OMSEM vs. OMSEM Optical microscope

Source of light electron beam wavelength: 2000~7500Awavelength : 0.064~

Medium vacuum air

Lens elect on lens optical lensLens electron lens optical lens

Resolution limit 30A~10A visible : 2000Aultra : 1000Aultra : 1000A

Focal depth 30 about 0.1Magnification 10~30 000 10~2000Magnification 10~30,000 10~2000 Kinds of phase secondary&reflec. Transmitted or reflected

Electron beam lithography

20 um

EBL Plasma EtchHSQ resist

g p y

20 um

e- e- e- e- e- 7

Silicon substratespin coat resist trim

e e e e e 7nm

exposure silicon etch10 HOURS!!10 HOURS!!

develop resist strip

80nm line70nm space

11nm 30nmdiameter

Transmission Electron Microscopy

• High e Energy (100~300keV)• Thin specimen (<2000Å)• Thin specimen (<2000Å)• Transmitted beam – bright

fieldfield• Diffracted beam – crystal

structurestructure• Very high resolution (0.15nm)

Thin section preparationThin section preparation

Ion milling법을 이용한 cross section 시료 제작Ion milling법을 이용한 cross-section 시료 제작

Scanning Prove Microscopy

Scanning Probe Microscopy

CNT on electrodesCNT on electrodesCNT on electrodesCNT on electrodes

Scanning Probe Microscopy

Spectroscopyp py

-Analysis for chemical structure identification

-Difference between scattering and spectroscopy?

-Rayleigh scattering

-UV/VIS, IR, Raman scattering

NMR spectroscopy

Scatteringg

-Structure analysis via

Small angle or wide angle x-ray scattering

Neutron scattering

Light scattering

X‐ray Scatteringy g

- Small angle or wide angle x-ray scattering

Wavelength of incident x-ray:

Small angle vs. wide angle:

Not only for bulk materials but also for films

elastic scattering: ki=kfelastic scattering: ki kf

ki kf

dd

2f t ti i t f 2k kfor constructive interference: 2k s k⋅ =

2 sinn dλ θ= 2 sinn dλ θ=

Synchrotron Radiation Facility

Storage ring at PLS

Pohang Light Source

LINAC Storage ring

just before front-end

Neutron Scatteringg

- Elastic vs. inelastic or quasi-elastic scattering

Wavelength:

Unique features of neutron beam:

Spallation Source: IPNS (Argonne National Lab, USA)

Neutron Reactor: NIST (USA)

Confined building

Guide hall

Sample stage

Detector chamber

Detector chamber (1)

Detector chamber (2)

Neutron Scatteringg

- Elastic vs. inelastic or quasi-elastic scattering

Wavelength:

Unique features of neutron beam:

elastic scattering: ki=kfelastic scattering: ki kf

ki kf

dd

2f t ti i t f 2k kfor constructive interference: 2k s k⋅ =

2 sinn dλ θ= 2 sinn dλ θ=

Scattering pattern of nanocrystal

Background of scattering

elastic scattering: ki=kfelastic scattering: ki kf

ki kf

dd

2f t ti i t f 2k kfor constructive interference: 2k s k⋅ =

2 sinn dλ θ= 2 sinn dλ θ=

( ) ( ) ir qA q r e drρ − ⋅= ∫

u( ) ( )* ( )r r z rρ ρ=FT

( ) ( ) ( )A q F q Z q=SLDD Scattering amplitude

∫

IFTForm factor lattice factor

uarin

g

X squ

*

( )( ) ( )

I qA q A q= ⋅

( )I q

for n atomic crystal

( ) ( ) ( )f∑ ∑

for n atomic crystal,

nj j( ) exp( ) exp( )j n

F q f iq r iq R= − ⋅ − ⋅∑ ∑

unit cell structure factor lattice sumPosition determination

2 integernq R π⋅ = ×

∑th i

nexp( ) ~n

iq R N− ⋅∑since

( ) 1i R∑otherwise, nexp( ) ~ 1n

iq R− ⋅∑

Real and inverse lattice

2 integerr q π⋅ = × (Laue condition ~ Bragg Law)

b b b2 32 a ab ×

1 1 2 2 3 3q v b v b v b= + +1 1 2 2 3 3r u a u a u a= + +

i j ij2

when 0

b a

i j

πδ⋅ =

≠

2 31

2 3 1

2ba a a

π=⋅ ×3 12 a ab × when , 0

when , 2i ji j π≠=

3 12

3 1 2

2ba a a

π=⋅ ×

a a×1 23

1 2 3

2 a aba a a

π ×=

⋅ ×

( )1 1 2 2 3 32r q u v u v u vπ⋅ = × + +

3b

a3a

2a

1a

Structure factor for a uniform sphere

[ ]2( ) ( )P F ρ~ 0ρ2 s qπ =

[ ]( ) ~ ( )P q F q ρ2R

( ) ( ) ( )F i d∫( ) ( ) exp( )F q r iq r drρ= − ⋅∫

Structure factors for several structures

Thin rod

At a certain orientations Θ a

4 cos( ) sin( )2

qLF qL

Θ=

Θ

At a certain orientations, Θ

Lcos 2qL Θ L

V=aLV aL

Circular disk

R1(2 )2( ) 1 J qRP q ⎡ ⎤

= −⎢ ⎥F 2 2( ) 1P qq R qR

= ⎢ ⎥⎣ ⎦

F

Structure factors for several structures

Circular disk

R

⎡ ⎤12 2

(2 )2( ) 1 J qRP qq R qR

⎡ ⎤= −⎢ ⎥

⎣ ⎦q q⎣ ⎦

How about this?--synthetic polymer, DNA, protein…synthetic polymer, DNA, protein…

[ ]2( ) ~ ( )P q F q

constant form factor?

Random coil 2 2 2 2exp( ) 1R R+Or Gaussian coil4 4

exp( ) 1( ) ~ 2 g g

g

q R q RP q

q R− − +

g

htt // i t / / / df/ l t t dfhttp://www.ncnr.nist.gov/programs/sans/pdf/polymer_tut.pdf