Polymer blends, Copolymers, and Liquid crystal polymers · 2018. 1. 30. · 12.1 Polymer...

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Chapter 12. Chapter 12. Polymer blends, Copolymers, and Liquidcrystal polymers

Transcript of Polymer blends, Copolymers, and Liquid crystal polymers · 2018. 1. 30. · 12.1 Polymer...

Page 1: Polymer blends, Copolymers, and Liquid crystal polymers · 2018. 1. 30. · 12.1 Polymer blends-Miscibility ΔG m

Chapter 12.Chapter 12.Polymer blends, Copolymers, and 

Liquid‐crystal polymers

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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

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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)

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– 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]

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– 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

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Melt-miscibleMelt miscible

SDNG SDNG

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LCST vs. UCST

When?

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Experimental detection of miscibility

Thermal analysis-Thermal analysis

-Microscopic analysisMicroscopic analysisSEM, TEM, AFM …

-Spectroscopy

what else?-what else?

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Experimental detection of miscibility-Thermal analysis-Thermal analysis

miscible

miscibleImmiscible

miscible

miscible

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Experimental detection of miscibility-SpectroscopySpectroscopy

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Compatibilizationp

- Using compatibilizerex. block or graft copolymerg p y

- Reactive compatibilizationReactive compatibilization

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Compatibilization – block or graft copolymer

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Compatibilization – Reactive blendingp g

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Principal polymer typesp p y yp

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Morphologyp gy

How about their properties and applications?How about their properties and applications?

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12.3 Copolymersp y

poly(A-alt-B)poly(A-co-B)p y( )poly(A-g-B)poly(A-b-B)p y( )

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What will be the difference betweenWhat will be the difference between copolymers and blends?

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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

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Cocontinuous gyroid phase

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Copolymers combining elastomeric and rigid components

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Segmented polyurethaneg p y

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Tg of copolymers combining elastomeric and rigid componentselastomeric and rigid components

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Block Copolymer Thin Film TemplateBlock Copolymer Thin Film Template

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High capacity, self-assembled MOS decoupling capacitorscapacitors

IBM

IEEE ELECTRON DEVICE LETTERS, VOL. 25, NO. 9, SEPTEMBER 2004

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Block Copolymer Thin Film TemplateBlock Copolymer Thin Film Template

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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)

Page 31: Polymer blends, Copolymers, and Liquid crystal polymers · 2018. 1. 30. · 12.1 Polymer blends-Miscibility ΔG m

High capacity, self-assembled MOS decoupling capacitorscapacitors

IBM

IEEE ELECTRON DEVICE LETTERS, VOL. 25, NO. 9, SEPTEMBER 2004

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Solvent annealing Solvent annealing –– long range orderlong range order

PS-PEO

Adv. Mater., 16, 226 (2004)

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Mesoporous Silicates Replicated from Block Copolymer Templates in Supercritical Fluids

Pai et al Science (2004)Pai et al., Science (2004)

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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.

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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)

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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

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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?

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LC polymer and mesogenic groupLC polymer and mesogenic group

Main chain LC polymer

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Side chain LC polymers

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