Chapter 12.Chapter 12.Polymer blends, Copolymers, and
Liquid‐crystal polymers
12.1 Polymer blends
-Miscibility
y
MiscibilityΔGm <0
-Flory-Huggins interaction parameterΔΗm = kTχ12x1x2
ΔG = kT [(x1ln x1)/N1+ (x2ln x2)/N2 + χv1v2]ΔGm kT [(x1ln x1)/N1+ (x2ln x2)/N2 + χv1v2]
- Miscibility and compatibilization
Statistical thermodynamics for regular sol’n
• ΔSm by lattice modelFilli & l l i + ll– Filling n1 & n2 molecules in n1+n2 = 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 fractionn ~ numberx1 = n1/(n1+n2)
n = n1 + n2
x1 n1/(n1+n2)
– applying molar quantities,N ~ number of molesN = N1+ N2R = k NA
• heat of mixing– for small molecules in the absence of specific interaction b dbetw 1 and 2
ΔE ~ heat of vapΔE heat of vap
• free energy of mixing
• among polymersΔG = kT [(x1ln x1)/N1+ (x2ln x2)/N2 + χx1x2]ΔGm = kT [(x1ln x1)/N1+ (x2ln x2)/N2 + χx1x2]
– 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 ~ unstableS ~ 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-miscibleMelt miscible
SDNG SDNG
LCST vs. UCST
When?
Experimental detection of miscibility
Thermal analysis-Thermal analysis
-Microscopic analysisMicroscopic analysisSEM, TEM, AFM …
-Spectroscopy
what else?-what else?
Experimental detection of miscibility-Thermal analysis-Thermal analysis
miscible
miscibleImmiscible
miscible
miscible
Experimental detection of miscibility-SpectroscopySpectroscopy
Compatibilizationp
- Using compatibilizerex. block or graft copolymerg p y
- Reactive compatibilizationReactive compatibilization
Compatibilization – block or graft copolymer
Compatibilization – Reactive blendingp g
Principal polymer typesp p y yp
Morphologyp gy
How about their properties and applications?How about their properties and applications?
12.3 Copolymersp 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 betweenWhat will be the difference between copolymers and blends?
Self‐assembly of Block Copolymers
PMMA PS B Sph.
A Sph.
Lamella
Sph.p
BA• Phase morphology depends on
relative polymer‐block chain lengths Gyroid
BCyl.
ACyl.
lengths• Length scale : 10 – 100 nm• PS‐b‐PMMA: PMMA can be easily
GyroidA B
ODTDisorderedy
removed (etched).fA (A component Volume Fraction)
spheres cylinders lamellae inversecylinders
inversespheres
gyroid inversegyroid
Cocontinuous gyroid phase
Copolymers combining elastomeric and rigid components
Segmented polyurethaneg p y
Tg of copolymers combining elastomeric and rigid componentselastomeric and rigid components
Block Copolymer Thin Film TemplateBlock Copolymer Thin Film Template
High capacity, self-assembled MOS decoupling capacitorscapacitors
IBM
IEEE ELECTRON DEVICE LETTERS, VOL. 25, NO. 9, SEPTEMBER 2004
Block Copolymer Thin Film TemplateBlock Copolymer Thin Film Template
Ordering of diblock copolymer on a substratePerpendicular order of cylindrical domains of block copolymer can be obtained by tuning the interactions.
Using Random Copolymer Brushto Produce Neutral Surface
Passivation of SiOx Surfaceto Form Si-H Surface
t ~ L0
PSPMMA
Science, 275, 1458 (1997)
PMMA
Silicon waferP(S-r-MMA)
High capacity, self-assembled MOS decoupling capacitorscapacitors
IBM
IEEE ELECTRON DEVICE LETTERS, VOL. 25, NO. 9, SEPTEMBER 2004
Solvent annealing Solvent annealing –– long range orderlong 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 PEO127-b-PPO48-127 48b-PEO127 BCP film dilated with scCO2 followed by calcination.
UltrahighUltrahigh--density nanowire arrays grown density nanowire arrays grown in selfin self assembled diblock copol me templatesassembled diblock copol me templatesin selfin self--assembled diblock copolymer templatesassembled diblock copolymer templates
PS-PMMA block copolymer :PS-PMMA block copolymer :20 nm diameter PMMA cylinders hexagonally packed in PS matrixg y pSpin coating onto conducting substrateUV exposure removes PMMA block andpolymerize PSFormation of 14 nm pores Electrodeposition of Co to obtain arrayElectrodeposition of Co to obtain array
Science, 290, 2126 (2000)
X ray scattering patterns at an angle of incidence at 45°X-ray scattering patterns at an angle of incidence at 45°.
(A)Before PMMA removal(A)Before PMMA removal(B)After PMMA removal
12.4 Liquid crystal polymersq y p y
Q What is LC state? Is it liquid or crystal?Q. What is LC state? Is it liquid or crystal?
LC polymer and mesogenic groupLC polymer and mesogenic group
Main chain LC polymer
Side chain LC polymers