Chapter 10 - PowerPoint Presentation

Slide1

Chapter 10Spinodal Decomposition in Binary Polymer Blends

Mat E 454 | April 22nd, 2014

Mohammed

Alzayer

Edward

Bruns

XIAOLIN BISlide2

OutlineIntroduction

Theory:Ideal Solution ModelRegular Solution ModelFlory-Huggins

Theory

The Cahn-Hilliard

Model

Fox

Equation

Binary Systems Exhibiting SD:

PMMA/ PαMSAN

PMMA/SAN

PEH/PEB

PMMA/PLLA

Incommensurate

Films

Composition-dependent

heat

conductivity systems

ConclusionSlide3

Introduction [1]Lower Boundary: thermally induced mixingUpper Boundary:

thermally induced demixingMaximum: Highest T for mixing (UCST)Minimum:

Lowest T for

demixing

(LCST)

Describing typical polymer blends phase diagrams

[1] Simmons, D. S. (2009). 

Phase and conformational behavior of

lcst

-driven stimuli responsive polymers

. (Doctoral dissertation, University of Texas

)Slide4

Introduction [1]Other Behaviors: LCST is the most common but..

[1] Simmons, D. S. (2009). Phase and conformational behavior of lcst-driven stimuli responsive polymers. (Doctoral dissertation, University of Texas)

There are others:

(a

), UCST only (b), LCST and UCST curves with multiple

extrema

(c and d). merged LCST and UCST (e), closed immiscibility loops (f), and combinations of LCST, UCST, and closed immiscibility loop behavior (g and h). Curves may represent either

spinodal

or

binodal curves. Slide5

IntroductionTo be immiscible, i.e. spinodal

decomposed:Criteria #1:2 or more chemically different polymers in

in a shared

volume

Criteria #2:

Phase separation between the polymers, macro-sized regions of similar-chemical polymer, or single polymer rich regions dispersed throughout homogenous mixture Slide6

The Ideal Solution Model [2]Obeys Raoult’s:

Enthalpy and entropy of mixing:

[2] Murat

, S. (2010). 

Physical chemistry of polymers: Thermodynamics of solutions of high polymers

. (Doctoral dissertation,

Hacettepe

University, Ankara, Turkey)

1 (solvent)

while 2

(solute).

a

is the

activity

of the component, X is the

mole

fraction, Pi is the vapor pressure of the solvent before mixing, and Pf is the vapor pressure of the solvent after

mixingSlide7

The Ideal Solution Model [2]Why does it fail to describe polymer blends?

A solution with a very small solute weight fraction as well as a small mole fraction (

) can hardly deviate from the

ideality.

Polymer solutions

consist of polymeric solutes with high molecular weights and mole fractions

(99%!)

[2] Murat

, S. (2010). 

Physical chemistry of polymers: Thermodynamics of solutions of high polymers

. (Doctoral dissertation,

Hacettepe

University, Ankara, Turkey) Slide8

The Regular Solution Model [3][4]How does it describe SD?Formation of

uni-polymer rich regions or phase separation of polymers from a seemingly uniform matrix/mixture.Why does it happen?SD occurs as a result of compositions lowering blend’s Gibbs free energy

[3] Martin, B. (2011). 

Phase transformations: Nucleation and

spinodal

decomposition

.

MIT. [

4]

Zang, L. 

Spinodal

Decomposition: Part 1: General Description and Practical Implications

. The University of Utah

.Slide9

The Regular Solution Model [3][4]Notes on the model:Points where

= 0

called

spinodes

(inflection points).

Spontaneous

phase separation

faces

no thermodynamic barrier. i.e

.

controlled solely by

diffusion.

[3] Martin, B. (2011). 

Phase transformations: Nucleation and

spinodal

decomposition

.

MIT. [

4]

Zang

, L. 

Spinodal

Decomposition: Part 1: General Description and Practical Implications

. The University of Utah

.Slide10

Flory-Huggins Theory [5][6]considers a low MW solvent and a high MW polymer

in a lattice:And the Flory Parameter is:

[5] Frank, C. (2001). 

Flory-

huggins

model for polymer solutions

. Stanford University.

[

6] Andersson, C. (2008). Flory-huggins

theory applied in atmospheric aerosol modelling. (Master's thesis, Stockholm University)

Where xi is molar

fraction of the

component, Z is coordination number (nearest # of neighbors in lattice), N is total number of lattice sites,

is

~ energy

of

formation,

and

is fraction of lattice sites occupied.

 Slide11

Flory-Huggins Theory [5][6]Why is χ commonly used?

It is independent of concentrationIt gives a better approximation of a:

[5] Frank, C. (2001). 

Flory-

huggins

model for polymer solutions

. Stanford University.

[

6] Andersson

, C. (2008). Flory-huggins theory applied in atmospheric aerosol modelling. (Master's thesis, Stockholm

University)

Where

is activity of water,

is volume fraction of polymer, and r is chain segment number (polymer volume to water volume ratio).

 Slide12

The Cahn-Hilliard Model [7]Why another model?1) Regular & ideal too

simple to model real cases 2) It considers chemical kineticsThe difference in concentration is given by

[

7]

Bukusoglu

, E., Pal, S. K., De Pablo, J. J., & Abbott, N. L. (2014). Colloid-in-liquid crystal gels formed via

spinodal

decomposition. 

Soft Matter, (10), 1602-1610.

where c is the concentration ,

is the

amplification

factor of the fastest growing wavelength, t is time,

is wavenumber, and

is the dominate wavenumber during system decomposition.

 Slide13

The Cahn-Hilliard Model [7]Why another model?D

ynamics of the SD modeled as a function of the depth of the thermal quench ():

[

7]

Bukusoglu

, E., Pal, S. K., De Pablo, J. J., & Abbott, N. L. (2014). Colloid-in-liquid crystal gels formed via

spinodal

decomposition. 

Soft Matter, (10), 1602-1610. Slide14

Fox Equation [8]What is it?Fox Equations among others utilized to predict Tg

[8] Madbouly, S. A. (2014). Mat E 454: Polymer composites and processing

(Lectures). Iowa State University.Slide15

Fox Equation [8]What is it?Fox Equations among others utilized to predict Tg

[8] Madbouly, S. A. (2014). Mat E 454: Polymer composites and processing

(Lectures). Iowa State University.Slide16

PMMA/ PαMSAN [9]Preparation:

tetrahydrofuran

PMMA

PαMSAN (31

wt

%

acrylonitrile)

,

PDI

14000

g/

mol

, 2.1

96500

g/

mol

, 2.26

tetrahydrofuran

PMMA

PαMSAN (31

wt

%

acrylonitrile)

14000

g/

mol

, 2.1

96500

g/

mol

, 2.26

[9]

Madbouly

, S. A., &

Ougizawa

, T. (2004).

Spinodal

decomposition in binary blend

of

PMMA/

PαMSAN:

Analysis of early and late stage

demixing

. 

Macromolecular Chemistry and Physics

, 

205

(7), 979–986.

Techniques:

Optical,

DSC (10 °C/min

), Time-

resoloved

light scattering (632.8 nm He-Ne)

1) Drying at r.t., 3 days, cast solution in Petri.

2) Further dried by vacuum for 3 days at 90 °C.

3)

Meltpressing

on a hot chamber, at constant T.

4) After annealing, thin film obtained, t=40 mm.Slide17

PMMA/ PαMSAN [9]Some observations: Near

critical composition 75:25. 1-phase (150 °C) to 2 phases (180 °C). Connectivity not clear until 20

mins

. Annealing

time increased,

contrast

of

2-phase increased. Late stage of

SD (50 mins), co-continuity lost result of coarsening. “fragmented particles.”

[9] Madbouly, S. A., & Ougizawa

, T. (2004).

Spinodal

decomposition in binary blend

of

PMMA/

PαMSAN:

Analysis of early and late stage

demixing

. 

Macromolecular Chemistry and Physics

, 

205

(7), 979–986.

10 min

20 min

50 minSlide18

PMMA/ PαMSAN [9]Notes:

LCST, miscible at a limited T range, miscible at entire w range (1 common , Fox), χ increases a lot with

T (slope

shift from negative to a small

positive) agrees with LCST.

[9]

Madbouly

, S. A., &

Ougizawa, T. (2004). Spinodal

decomposition in binary blend

of

PMMA/

PαMSAN:

Analysis of early and late stage

demixing

. 

Macromolecular Chemistry and Physics

, 

205

(7), 979–986. Slide19

PMMA/SAN [10]Why add nanoparticles?

Ability to control morphology, improve electrical properties, change phase

separation

T and

phase diagram. B

ehavior

becomes more complicated.

One of the polymers

absorbs the other, changing the thermodynamics.

PMMA

SAN

, PDI

, 1.64

, 2.08

96

105

PMMA

SAN

[10] Gao, J., Huang, C., Wang, N., Yu, W., & Zhou, C. (2012). Phase separation of

PMMA/SAN blends

in the presence of silica nanoparticles. 

Polymer

, 

53

(8), 1772–1782. Slide20

PMMA/SAN [10]Ajji and Choplin’s

Equation to get Ts and Tb:

[10] Gao, J., Huang, C., Wang, N., Yu, W., & Zhou, C. (2012). Phase separation of

PMMA/SAN blends

in the presence of silica nanoparticles. 

Polymer

, 

53

(8), 1772–1782. Slide21

PMMA/SAN [10]Effect of size: The bigger the particle,

the lower the Tb. Micron sized hardly have an effect (T

b

~ T

b pure

). T

b

increases with more particles added.

SiO

2

content

3%

3%

3%

-

1%

5%

SiO

2

diameter (nm)

12

30

1000

-

30

30

Tb (°C)

172.2

171.8

169

167

171.3

174.5

[10] Gao, J., Huang, C., Wang, N., Yu, W., & Zhou, C. (2012). Phase separation of

PMMA/SAN blends

in the presence of silica nanoparticles. 

Polymer

, 

53

(8), 1772–1782. Slide22

PEH/PEB [11]Preperation: Heat treatments (separation at 130

oC), quenched into liquid nitrogen causing fracture, etched by 1% potassium permanganate in a mixture of sulfuric acid and

orthophosphoric

acid

for contrast.

[11] Yang, L.,

Yanhua, N., Wang, H., & Wang, Z. (2009). Effects of spinodal

decomposition on mechanical properties of a polyolefin blend from high to low strain rates. Polymer, 50(13), 2990–2998.

PEH

PEB

110000g/

mol

70000g/

mol

Contains

2

mol

%

hexane

15

mol

%

butane

Thickness and shape

0.5 mm dog bone

PEH

PEB

110000g/

mol

70000g/

mol

Contains

2

mol

%

hexane

15

mol

%

butane

Thickness and shape

0.5 mm dog boneSlide23

PEH/PEB [11]High strain rate (0.01s-1):

interfacial relaxation between phase domains cannot be detected. Low strain rate (0.001s-1):

drop of tensile properties

with

separation when

Tc

is low. The effect disappears at high

Tc.

[11] Yang, L., Yanhua, N., Wang, H., & Wang, Z. (2009). Effects of

spinodal decomposition on mechanical properties of a polyolefin blend from high to low strain rates. Polymer, 50

(13), 2990–2998. Slide24

PMMA/PLLA [12]In the figure: “Tapping-mode AFM images

of monolayers mixtures (25/75,50/50, and 75/25 weight fraction) deposited on mica at surface pressure

1

, 5, 10, and 12

mN

/m. F

ibrils at surface

pressure higher than 10 mN/m are crystallized PLLA lamella.”

[12] Sato, G.,

Nishitsuji, S., & Kumaki, J. (2013). Two-dimensional phase separation of a poly(methyl methacrylate)/poly(l-lactide

) mixed

langmuir

monolayer via a

spinodal

decomposition

mechanism.

The

Journal of Physical Chemistry

, 

117

(30), 9067–9072. Slide25

PMMA/PLLA [12]2D: Analogous to 3D’s nucleation and

growthSpinodal ring: FFT shows doughnut

like pattern

in inserts. Phase-separated

structures possess

concentration

fluctuation with a specific

λ:

Early Stage: wavelength of dominant mode is independent

of t, whereas the concentration fluctuations, Δϕ(t), grow with time

[12] Sato, G.,

Nishitsuji

, S., &

Kumaki

, J. (2013). Two-dimensional phase separation of a poly(methyl methacrylate)/poly(l-

lactide

) mixed

langmuir

monolayer via a

spinodal

decomposition

mechanism.

The

Journal of Physical Chemistry

, 

117

(30), 9067–9072. Slide26

PMMA/PLLA [12]Intermediate stage:

described by both λ and Δϕ(t) growing with time.F

inal stage:

λ increases with time, while

Δϕ

(t) already saturates to its equilibrium

value.

[12] Sato, G.,

Nishitsuji, S., & Kumaki, J. (2013). Two-dimensional phase separation of a poly(methyl methacrylate)/poly(l-

lactide) mixed langmuir monolayer via a

spinodal

decomposition

mechanism.

The

Journal of Physical Chemistry

, 

117

(30), 9067–9072. Slide27

Incommensurate Films [13]Top: 2.5 µm of film surface at

160 min, majority perpendicular lamellar morphology (PS dark, PMMA light). [13] Peters, R. D.,

Pawel

, S.,

Matsen

, M. W., &

Dalnoki-Veress

, K. (2013). Morphology induced spinodal

decomposition at the surface of symmetric diblock copolymer films. ACS Macro Letters, 

2(5), 441–445.

Bottom:

SCFT

calculation of mixed morphology intermediate state

.Slide28

Composition-dependent Heat Conductivity Systems [14]Quench conditions: structure

resulting from SD varies with quench condition.Example: in the figure, the left wall is quenched, while the right wall is insulated

[14]

Molin

, D., &

Mauri

, R. (2008).

Spinodal

decomposition of binary mixtures with composition-dependent heat conductivities. 

Chemical Engineering Science, 63(9), 2402–2407. Slide29

Composition-dependent Heat Conductivity Systems [14]

λ stands for heat conductivity ratio, while â is a characteristic length and D is a mass diffusivity parameter. Overall, the 105 â2

/D translates between 1-10 seconds. N

LE

, the

lewis

number, stands for the ratio of thermal to mass diffusivity.

[14]

Molin, D., & Mauri, R. (2008).

Spinodal decomposition of binary mixtures with composition-dependent heat conductivities. Chemical Engineering Science, 

63

(9), 2402–2407. Slide30

ConclusionFrom this presentation: we can conclude that

spinodal decomposition is important in polymers science.We can take it further:

improve the miscibility of blends by introducing a third

polymer (

compatibilizar

).

It’s beyond this chapter:

no longer binary, but rather ternary.

Why ternary? High concentration of third polymer is needed.