Chapter 12.
Chapter 12.
Polymer blends, Copolymers, and
Liquid‐crystal polymers
12.1 Polymer blends
-Miscibility
y
Miscibility ΔG
m<0
-Flory-Huggins interaction parameter ΔΗ
m= kTχ
12x
1x
2ΔG = kT [(x
1ln x
1)/N
1+ (x
2ln x
2)/N
2+ χv
1v
2]
ΔG
mkT [(x
1ln x
1)/N
1+ (x
2ln x
2)/N
2+ χv
1v
2]
- Miscibility and compatibilization
Statistical thermodynamics for regular sol’n
• ΔS
mby lattice model
Filli & l l i + ll
– Filling n
1& n
2molecules in n
1+n
2= n cells
• volume of 1 ≈ volume of 2 (small molecules)
Boltzmann relation S = k ln P – Boltzmann relation, S = k ln P
• P ~ number of (distinguishable) ways
x ~ mol fraction n ~ number x1 = n1/(n1+n2)
Å n = n1 + n2 x1 n1/(n1+n2)
– applying molar quantities,
N ~ number of moles N = N1+ N2
R = k NA
• heat of mixing
– for small molecules in the absence of specific interaction
b d
betw 1 and 2
ΔE ~ heat of vap ΔE heat of vap
• free energy of mixing
• among polymers
ΔG = kT [(x
1ln x
1)/N
1+ (x
2ln x
2)/N
2+ χx
1x
2]
ΔG
m= kT [(x
1ln x
1)/N
1+ (x
2ln x
2)/N
2+ χx
1x
2]
– betw B and S ~ metastable B ~ bi d l i t
• B ~ binodal point
– at B, dG/dx1 = μ1 = μ2 = dG/dx2
• local minor composition fluctuation
‐ betw the two S’s ~ unstable
S ~ i d l i t ~ d2G/d 2 0 • local minor composition fluctuation – raise energy
– back to homogeneous solution
• S ~ spinodal point ~ d2G/dx2 = 0
• Local minor composition
fluctuation g
• major fluctuation like nucleation – phase separate to B comp
‐lower the energy
‐fluctuation stabilized
‐phase separate (1‐rich + 2‐rich)
– ‘nucleation and growth’
– outside B’s ~ stable
• single phase is stable
• ‘spinodal decomposition’
co‐continuous to discontinuous
• single phase is stable
Melt-miscible Melt miscible
SD
NG SD
NG
LCST vs. UCST
When?
Experimental detection of miscibility
Thermal analysis -Thermal analysis
-Microscopic analysis Microscopic analysis
SEM, TEM, AFM … -Spectroscopy
what else?
-what else?
Experimental detection of miscibility -Thermal analysis
-Thermal analysis
miscible miscible Immiscible
miscible
miscible
Experimental detection of miscibility
-Spectroscopy Spectroscopy
Compatibilization p
- Using compatibilizer
ex. block or graft copolymer g p y
- Reactive compatibilization Reactive compatibilization
Compatibilization – block or graft copolymer
Compatibilization – Reactive blending p g
Principal polymer types p p y yp
Morphology p gy
How about their properties and applications?
How about their properties and applications?
12.3 Copolymers p y
poly(A- alt -B) poly(A- co -B)
p y( )
poly(A- g -B) poly(A- b -B)
p y( )
What will be the difference between What will be the difference between
copolymers and blends?
Self‐assembly of Block Copolymers
PMMA PS
BSph.
A Sph.
Lamella p Sph.
A B
• Phase morphology depends on relative polymer‐block chain
lengths
GyroidB Cyl.
A Cyl.
lengths
• Length scale : 10 – 100 nm
• PS‐b‐PMMA: PMMA can be easily
Gyroid A B ODT
Disordered
y removed (etched).
fA (A component Volume Fraction)
spheres cylinders lamellae inverse
cylinders
inverse spheres
gyroid inverse
gyroid
Cocontinuous gyroid phase
Copolymers combining elastomeric and rigid components
Segmented polyurethane g p y
Tg of copolymers combining
elastomeric and rigid components
elastomeric and rigid components
Block Copolymer Thin Film Template
Block Copolymer Thin Film Template
High capacity, self-assembled MOS decoupling capacitors
capacitors
IBM
IEEE ELECTRON DEVICE LETTERS, VOL. 25, NO. 9, SEPTEMBER 2004
Block Copolymer Thin Film Template
Block Copolymer Thin Film Template
Ordering of diblock copolymer on a substrate
Perpendicular order of cylindrical domains of block copolymer can be obtained by tuning the interactions.
Using Random Copolymer Brush to Produce Neutral Surface
Passivation of SiOx Surface to Form Si-H Surface
t ~ L0
PS PMMA Science, 275, 1458 (1997)
PMMA
Silicon wafer P(S-r-MMA)
High capacity, self-assembled MOS decoupling capacitors
capacitors
IBM
IEEE ELECTRON DEVICE LETTERS, VOL. 25, NO. 9, SEPTEMBER 2004
Solvent annealing
Solvent annealing –– long range order long range order PS-PEO
Adv. Mater., 16, 226 (2004)
Mesoporous Silicates Replicated from Block Copolymer Templates in Supercritical Fluids
Pai et al Science (2004) Pai et al., Science (2004)
A highly ordered mesoporous silicate film prepared by infusion
and condensation of TEOS within a preorganized PEO
127127-b-PPO
4848-
b-PEO
127BCP film dilated with scCO
2followed by calcination.
Ultrahigh
Ultrahigh--density nanowire arrays grown density nanowire arrays grown in self
in self assembled diblock copol me templates assembled diblock copol me templates in self
in self--assembled diblock copolymer templates assembled diblock copolymer templates
z PS-PMMA block copolymer :
z PS-PMMA block copolymer :
20 nm diameter PMMA cylinders hexagonally packed in PS matrixg y p
z Spin coating onto conducting substrate
z UV exposure removes PMMA block and polymerize PS
z Formation of 14 nm pores
z Electrodeposition of Co to obtain array
z Electrodeposition of Co to obtain array
Science, 290, 2126 (2000)