resin-fortified emulsion polymerizations · 2013-12-26 · 기능성초미립자공정연구실...

기능성 초미립자 공정연구실

Homepage : http://www.nanotech.or.kr

Resin-Fortified Emulsion Polymerizations

Doug-Youn Lee([email protected])

Nanosphere Process & Technology LaboratoryDepartment of Chemical Engineering, Yonsei University


Emulsion Polymerization

ProductionBillions of metric tons/year

Advantages- High rate of polymerization - High molecular weights- Low viscosity- Excellent heat transfer- High conversions- Continuous production possibility


Applications of Latexes

Synthetic elastomer Surface coatings Adhesive Carpet backing Paper additives & coatingsWell-characterized monodisperse particle for fundamental colloid research Medical uses

Diagnostic test

Smart bombs

Pore size measurements

Electron microscope calibration standards Mortar reinforcement


• Wetting and adherency problems• Low gloss or mudcaking of resulting films• Mechanical instability• Freeze-thaw instability• Shear thinning property• Poor physical properties of the resulting films

Drawbacks of Emulsion Polymers

• Poor water and corrosion resistance of resulting films• Poor adhesion especially to metal surfaces

Disadvantage of Surfactants


Resin-Fortified Emulsion Polymers

Emulsion Polymer• High Molecular Weight• Toughness• Mechanical Strength

Low Mw Resin • Stability• Physical properties • Alkali Dispersibility• Gloss• Crosslinkability • etc.

Resin-fortified Emulsion Latex

• Fine particle size emulsions• Excellent film property• High gloss property• Newtonian-like rheological property• Excellent mechanical stability and

freeze-thaw stability• Excellent wetting property


Resin-Fortified Emulsion Polymerization

Fig. Schematic Representation of Emulsion Polymerization of Styrene in the Presence of Carboxylated Alkali-Soluble Resin.

Aggregate of Fuctional Resins in Aqueous Phase

Resin-Fortified Latex Particles


• Type of ASRs- Acrylic Resin (St/AMS/AA or BA/AA etc.)- SMA (Styrene Maleic Anhydride) Resin- EAA (Ethylene Acrylic Acid) Resin- Polyurethane Resin, etc.

• Number Average Molecular Weight : 500 - 20,000(Preferably : 2,000 - 4,000)

• Acid Number : 50 - 300• Soluble or Dispersible in Water or Alkali• Useful as Emulsifier, Leveling agent, and Film-former

• *acid number: the number of mg of KOH required to neutralize 1g of resin

Alkali-Soluble Resin (ASR)


Acrylic Resin

Fig. Schematic Representation of

Low MW SAA.

• Low Mw Polymer Containing Carboxyl Groups- poly(styrene/alpha-methylstyrene/acrylic acid) (SAA)

(St : AMS : AA = 35 : 33 : 32)- Mn : 4,300 , Mw : 8,600 , PDI : 2.0

• Acid Number : 190• Tg : 115 oC• Soluble in water and amine or alcohol, etc• Useful as emulsifier, leveling agent, and

film-former• Applications

- Floor Polishing- Adhesive- Paper Coating & Metal Coating- Binder & Sizing- etc.

HOOC

COOH

COOH

HOOC

COOH

COOH


• Pigment Dispersion• High Gloss & Excellent Clarity• Transfer Property & Printability• Solublility

- soluble in water and amine or alcohol, MEK etc.

• Compatibility- excellent compatibilty with styrene-acrylic emulsions, as well as SMA

and maleic resins.• Viscosity Stability• Applications

- multi-functional properties in water and solvent based ink and coatings.- source of carboxyl functionality so that inks and coatings can be further

crosslinked to provide heat and chemical resistance.

Properties and Characteristics of SAA


Excellent stability and physical properties System having most of the advantages of both bulk and emulsion

polymer system without their disadvantages

• Fine particle size emulsions• Excellent film property• High gloss property

• Newtonian-like rheological property

• Excellent mechanical stability and

freeze-thaw stability

• Excellent pigment dispersity and

wetting property

SAA Resin-Fortified Emulsion Polymer System

Latex Particle


Mw103 104 105 106

Are

a (%

)

0

1

2

3

4

5

Fig. Molecular Weight Distributions of Resin-Fortified Latexes Prepared Using SAA.

SAA Resin-Fortified Emulsion Polymer System

Fig. TEM photographs of PMMA latex prepared with 35 wt % of SAA.


• Graphic Art• Ink Binder• Pressure Sensitive Adhesive

- Excellent adhesion

• Paper Coating- High gloss property- Crosslinkable

W. J. Blank, R. E. Layman, US patent 4,151,143 (1979)S. L. Tsaur, US patent 4,820,762 (1989)G. R. Frazee, US patent 4,845,149 (1989)

Applications of SAA Resin-Fortified Polymer System


Table Basic Recipe of PSA in the Presence of ASR

Components Wt %

D.D.I Water 49.14Alkali-Soluble Resin(ASR)

[poly(BA(70%)/AA(30%)] Mn: 2000 11.93Ammonium Hydroxide (NH4OH) 2.39Nonionic Surfactant 0.48

MonomerMMA(10)/2-EHA(77)/BA(10)/TEGDA(3) 35.81

InitiatorAmmonium Persulfate 0.25

Resin-Fortified PSA Formulation


• Excellent water resistance, tack and adhesion • Fine particle size emulsions• Emulsion viscosities which can be varied from low to

high with no sacrifice in stability• Emulsion viscosities which are stable under high shear

conditions in roll coating operation- Newtonian-like flow characteristics

• Low foam production which is desirable in roll coating operation

Advantages of Resin-Fortified PSA


Emulsion PolymerizationUsing SAA Resin


SAA Concentration (wt%)

10-6 10-5 10-4 10-3 10-2 10-1 100

Surf

ace

Tens

ion

(dyn

e/cm

)

45

50

55

60

65

70

75

UV

Abs

orba

nce

0.0

.2

.4

.6

.8

Aggregate Formation of SAA in Aqueous Solution

Fig. UV absorbance of pyrene at 360nm and surface tension of SAA solution as a function of SAA concentration. (wt% based on total)

• Critical Micelle Concentration: 10-2 wt %

• The increase in pyrene solubility with SAA concentration indicated the formation of SAA aggregates like micelles in aqueous solution.

• Also, a gradual decrease and leveling off ofsurface tension indicated that SAA formedaggreagtes.


Degree of Neutralization of SAA Resin

Effect of Neutralization Degree on Emulsion Kinetics

Degree of Neutralization (%)

Low Degreeof Neutralization

Excess Additionof Neutralization Agent

Solubilizing ability,


Emulsion Polymerization Using ASR as Emulsifier 1. Formation of Aggregates

HOOC

COOH

COOH

HOOC

COOH

COOH

Neutralization

Important Factors determiningthe Characteristics of Aggregates1. Acid Number2. Degree of Neutralization3. Molecular Weight & Structure4. Temperature,…, etc.

: Monomer

Swelling

2. Emulsion Latexes in the Presence of ASR

Free Radical( j > z-mer)

. Monomer-swollen Polymer Particle

Core/Shell Morphology

ASR Grafted ASR

Polymerization


Figure TEM photographs of PMMA latex prepared with 35 wt % of ASR: degree of neutralization of ASR; (a) 80 %, (b) 100 %.


SAA Concentration0 5 10 15 20 25 30 35 40

Dn

(nm

)

32

34

36

38

40

42

44

46

48

Fig. Polystyrene latex particle size as a function of SAA concentration (wt % based on monomer).

Particle Size of Polystyrene Particles

• The PS latex particle size decreasedwith increasing the concentration of ASR

• This result was similar to that obtained in the emulsion polymerization usingconventional surfactant


Grafting Reaction of SAA

- This result indicated that the grafting of PS to SAA occurred during emulsion polymerization

1st Ammonia Water 2nd Toluene

1st, 2nd developed solvent

0

10

0

10

ASR

PS &ASR-g-PS

ASR

ASR-g- PS

PS

TLCColumn

Glass Box

1st 2nd

TLC-FIDSeparation Technique

Iatroscan MK-5 TLC/FIDanalyzer

Fig. TLC-FID chromatographic scanning showing separation of the polystyrene latexes into three components; the ungrafted ASR, ungrafted polystyrene, and the ASR-grafted polystyrene.


Fig. Schematic Representation of Latex Particle Grafted and Adsorbed

with Alkali-Soluble Resin.

Latex Particle Stabilized with SAA

• In emulsion polymerization using SAA,SAA containing a large number of carboxylgroups results in electrosterically stabilizedlatexes

Stabilization Mechanism- Electrosteric Stabilization


• SAA was adsorbed and grafted on the surface of the final latex particle, whichresulted in small-sized carboxylated latex

• The zeta potentials of final latexes showed high values due to SAAs whichwere concentrated on the surface of latex particle

pH3 4 5 6 7 8 9 10 11

Zeta

Pot

entia

l (m

V)

-70

-60

-50

-40

-30

-20

-10

[ASR] = 35 wt%[ASR] = 10 wt%

Fig. pH dependence of zeta-Potential of PS Latex Particle Prepared at Different Concentration of SAA

Zeta-Potential of SAA-Fortified Latex Particle


Rate of Polymerization

Measure heat of reaction, ,from reaction calorimeterQr

Rate of Polymerization, Rp

RQ

V Hpr

H O p=

2Δ

: heat of reaction (J/s)

: total volume of water (L)

: heat of polymerization of styrene (J/mol)

Calorimetric Conversion

( )( )

( )( )X t

Q t dt

Q t dtX tc

r

t

r

t c ff=0

0

: calorimetric conversion

: evolution of heat of reaction

: overall calorimetric conversion of the final latex

- Reaction Calorimetric Technique

ΔHp

VH O2

rQ ( )X tc

( )Q tr

( )X tc f


Rp in SDBS vs. SAA Systems

• Despite the almost same particle sizeRp in SAA system was lower than thatin SDBS system.

• This result can be explained by the adsorp-tion of SAA onto the latex particles, which can influence the entry and exit of radicals.

• Average Partcle SizeDn ([SDBS] = 10 wt %) = 54 nm Dn ( [SAA] = 15 wt %) = 52 nm

• Rp is proportional to average number of radicals per particle.Reaction Time (min)

0 20 40 60 80 100

Rp

(x10

-4 m

oles

/L. s)

0

1

2

3

4

5

6

7

Cal

orim

etri

c C

onve

rsio

n0

20

40

60

80

100

SDBS System SAA System

Fig. Rate of polymerization in emulsion polymerization of styrene using SDBS and SAArespectively.

The kinetic of emulsion polymerization using SAA and conventionalionic emulsifier was conducted to study directly any effect of SAA.


Radical Diffusion in SDBS and SAA Systems

SDBS(Anionic Surfactant) System SAA System

• Thin Electrical Double Layer

• Higher radical entry rate

• Thicker Electrosteric Layer (Hairy Structure)

• Decrease in radical entry in the electrostericallystabilized latex is ascribed to hairy layer around the particle surface.

monomeric radical

Monomer SwollenPolymer Particle

monomeric radical

Electrosteric Layer


• It was assumed that the system entersInterval III after the maximum heat ofpolymerization.

• Rate expression for emulsion polymn.

• This supports that SAA has an influence on radical entry & exit, which lowers theaverage number of radicals per particle.

• n for the SAA system is lower than that for the SDBS system.

Fractional Conversion.3 .4 .5 .6 .7 .8 .9

Ave

rage

Num

ber

of R

adic

als p

er P

artic

le

0.0

.1

.2

.3

SDBS System SAA System

Fig. Average number of radicals per particle ( n ) vs. conversion in emulsion polymerization of styrene using SDBS and SAA respectively.

[ ]n

R Nk M N

p A

p p p=

n Calculation in SDBS vs. SAA Systems


Effect of SAA Concentration on Rp

• This result is quite different from that of conventional emulsion polymerization ofstyrene run earlier.

SAA Concentration10 15 20 25 30 35 40

Part

icle

Siz

e [D

n (n

m)]

40

42

44

46

48

50

52

54

• Although a decrease in particle size was observed, the Rp decreased with increasingSAA concentration.

Reaction Time (min)0 20 40 60 80 100

Rp

(x10

-4 m

oles

/L. s)

0

1

2

3

4

5

6

[SAA] = 15 wt %[SAA] = 25 wt %[SAA] = 35 wt %

Fig. Rate of polymerization in emulsion polymerization of styrene for different concentration of SAA. (wt% based on monomer)


Low Concentration SAA System High Concentration SAA System

• Thin electrosteric SAA Layer

• Relatively higher radical entry rate

• Thicker electrosteric SAA Layer

• More difficult for radicals to reach the particles

• This effect lowers the average number of radicals per particle.

monomeric radical

Monomer SwollenPolymer Particle

monomeric radical

Radical Diffusion For Different SAA Concentrations


Reaction Time (min)0 20 40 60 80 100

Rp

(x10

-4 m

oles

/L. s)

0

1

2

3

4

5

6

80 % Neutralization100 % Neutralization

Fig. Rate of polymerization in emulsion polymerization of styrene for different degree of neutralization of SAA.

• The increase in Rp may be explained by the solubilizing ability of SAA aggregate and the radical entry into the particle.

• With increasing the neutralization degree of SAA, the Rp of styrene decreased.

• As the degree of neutralization increased,the SAA micelles of low neutralization is less efficient in capturing radicals and solu-bilizing the monomer.

Effect of % Neutralization of SAA on Rp


Emulsion Polymerization Using SAA ResinsEffect of Neutralization Degree

Degree of Neutralization (%)

Low Degreeof Neutralization

Excess Additionof Neutralization Agent

A B C

Rp & nincreased

Rp & nincreased

Note: Low rate of instantaneous termination or radical exit from the particle may be due to viscose and dense shell


Effect of Electrolyte Contents on Rp

Time (min)0 20 40 60 80 100

Rp

(x10

-4 m

oles

/L. s)

0

1

2

3

4

5

6

No NaCl[NaCl] = 0.086 M

Fig. Rate of polymerization vs. time in emulsion polymerization of styrene for different electrolyte contents. [SAA]=15 wt %(wt% based on monomer)

• Significant increase in Rp as the electrolyte contents increased with little change in particle size.

• Effect of electroytes - solubilization ability of SAA aggregates- capture efficiency of radical

• The effect was explained as a consequence of an increase in solubilization ability of SAA aggregates and enhanced rate of radicalentry.


Film Formation & Properties


Temperature (oC)

-50 0 50 100 150 200

log

E' (P

a)

3

4

5

6

7

8

9

tan

δ

0

1

Fig. Dynamic mechanical properties of 10 wt% SAA-blended PBMA latex film as a function of temperature; storage modulus (E’); damping curve (tanδ).

• The spectrum shows distinct relaxations due to immiscibility

between PBMA and SAA

Dynamic Mechanical Property for Blend System


Figure Schematic of an atomic force microscopy (AFM) showing the force sensing cantilever.

Nanoscope III AFM(Digital Instruments, Inc, USA)

Atomic Force Microscopy


AFM Images of PBMA+10%SAA Before Annealing

Fig. Atomic force micrographs of PBMA latex film containing 10% SAA before annealing.


Fig. Three-dimensional AFM surface images of PBMA latex film containing 10% SAA and annealed for 10 min at 90 oC.

AFM Images of PBMA+10%SAA, 90oC for 10min


ATR FTIR Spectra

(A) before annealing(B) after annealing for 60 min at 90oC

710 to 690 cm-1 region :typical absorption peak for benzene ring

Attenuated total reflectance FTIR:(Perkin-Elmer model 2000)

Wavenumbers (cm-1)

800100012001400

Inte

nsity

Before annealingAfter annealing

690-710 cm-1

(A)

(B)

Fig. ATR FTIR spectra showing the 710 to 690 cm-1 region of the air/film interface of PBMA latex film containing 10% SAA.


Grafting Reaction in Resin-Fortified Polymer System

Ungrafted PBMA

Ungrafted SAA

Ungrafted SAA

Ungrafted PBMASAA-g-PBMA

(a)

(b)

Fig. TLC/FID chromatographic scanning curves of PBMA latex prepared with SAA; (a) 10 wt % SAA-blended PBMA latex film, (b) 10 wt % SAA-fortified latex film.

Grafting Efficiency:50 - 80%


Dynamic Mechanical Properties of SAA-fortified PBMA

Temperature (oC)

-50 0 50 100 150 200

log

E' (P

a)

5

6

7

8

9

tan

δ

0.0

.4

.8

1.2(a)

Temperature (oC)

-50 0 50 100 150 200

log

E' (P

a)

5

6

7

8

9

tan

δ

0.0

.4

.8

1.2

(b)

Fig. Dynamic mechanical properties of SAA-fortified PBMA latex films as a function of temperature; storage modulus (E′); damping curve (tanδ); (a) 10 wt % of SAA, (b) 20 wt % of SAA


Other Resin-Fortified Systems


Polyurethane Resin1. Basic Urethane Chemistry

Polyaddition between di(poly)ol and di(poly) isocyanate group Segmented structure: soft and hard segments Various kinds of polyurethanes can be synthesized

2. Water-soluble Polyurethane Resin

Polyurethane resins have carboxylic acids (DMPA) and they located randomly at polymer backbone

Characteristics :•Water-dispersible or water-soluble •Low CMC and high solubilizing ability •Molecular Weight: 5,000 - 15,000; •Acid Number: 31 - 50 mg KOH/g PUR

OHOCN+ N

HO

O

HOOC

COOH

COOH

HOOC

COOH

COOH


Preparation of Polyurethane Resins

Synthetic Procedure

OH

OH

OH

O

DMPA

NCO

OCN

IPDI

+

Non-reactive polyurethane resin: PUR-750 and PUR-2000

NH

O

NH

OO

O NH

O

n

O

OOH

O NH

O

OO

H

n

OHO

Hn

PPG

+Stoichiometric balancein NCO and OH values

OOH

O

OHO

Hn

PPG

+ Excess residual NCO

+ 2-hydroxyethyl methacrylate (HEMA)

Reactive polyurethane resin: PUR-750HEMAO O

NH

O

NH

OO

O NH

O

n

O

OOH

O NH

O

O


Concentration dependence of the I1/ I3 Ratioof pyrene fluorescence for PU Resins(25oC)

Concentration of PU resins (g/dm3 water)

10-6 10-5 10-4 10-3 10-2 10-1 100 101

I 1 / I 3

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

7.5x10-4 2.1x10-3

PU2000PU750

Polyurethane Resin

PUR-2000PUR-750

TEM Photo of Polyurethane Resins (× 30 K) Non-reactive type polyurethane resins

at 100% neutralization degree Amorphous structure due to low Mw and

low Tg

Polyurethane Resin Aggregates


Emulsion Polymerization Using Polyurethane ResinsElectron Microscopy Analysis

[SDS]o = 5wt.%(monomer)[KPS]o = 0.93mM water

[PUR750]o = 5wt.%(monomer)[KPS]o = 0.93mM water

Suggested driving forces affecting continuous nucleation

1. Low CMC and small aggregation number of the polyurethane resin

2. High solubilization ability forhydrophobic materials

RemarkSelf-aggregate of polyurethane molecules can be polymerizationlocus, even below CMC


Properties of Ethylene-Modified LatexUsing Ethylene-Acrylic Acid Resin

Emulsion Polymer• High Molecular Weight

• Toughness

• Mechanical Strength

EAA resin• Alkali Dispersibility• Crosslinkability• Barrier• Chemical Resistance

Ethylene-modified Latex

[Mn: 18,800, acid number: 140]


• PAPER COATING- Excellent water, grease and oil resistance- Excellent adhesion - Repulping property- High gloss property- Crosslinkable- High wet strength retention

• PAPER AND PAPERBOARD SATURATION AND SIZING

• METAL COATING, etc.

EAA Resin-Fortified Emulsion Polymer


Particle size (nm)0 50 100 150 200

Inte

nsity

0

20

40

60

80

100

120

140EAA 60 wt% ; Dn = 69.1nm, Dw = 74.7nmEAA 50 wt% ; Dn = 75.6nm, Dw = 81.2nmEAA 40 wt% ; Dn = 82.4 nm, Dw = 101.1 nm

Figure. Particle size and size distribution of ethylene-modified polystyrene with different EAA concentration at 140% degree of neutralization of EAA.

Latex Particle Size with Concentration of EAA

• As the concentration of EAA as apolymeric emulsifier increases,particle size is smaller and sizedistribution becomes narrow.

• Polydispersity is affected by :- water solubility of monomer- concentration of EAA as a

polymeric emulsifier.


EAA content (wt%)10 20 30 40 50 60 70

Perm

eabi

lity

(g m

m/m

2 da

y)

3.0

3.5

4.0

4.5

5.0

Effect of EAA Concentration on Permeability

Figure. Permeability of ethylene-modifiedPBMA latex film with different EAA concentration.

PBMA filmEMPB-E20 filmEMPB-E40 filmEMPB-E60 filmEAA film

8.12674.22763.90463.55680.2275

Permeabilitya

(g mm/m2 day)

Table. Permeability of PBMA Films and Pure EAA Film.

a measured at 20oC and 90% RH.b % based on monomer.* All sample drying at 40oC.


EAA concentration (wt% based on PS)20 40 60

Wei

ght L

oss (

%)

0

10

20

30

40

50

60Ethylene-Modified PSThe Simple Blends

Figure. Weight loss of ethylene-modified PS and the simple blends of PS/EAA as a function of EAA concentration after their immersion to methyl ethyl ketone for 5 hours.

Table. Percentage Weight Losses ofEthylene-Modified Latex Films and the SimpleBlending Films of PS and EAA after TheirImmersion to Methyl Ethyl Ketone for 5 Hours

WeightLoss %

WeightLoss %

EMPS-E60

1.72SBPS-

E6041.0%

EMPS-E40

2.26SBPS-

E4046.8%

EMPS-E20

6.61SBPS-

E2055.8%

Chemical ResistanceThe chemical resistance of ethylene-modifiedPS films is about 20 times higher than that ofsimple blends.

resin-fortified emulsion polymerizations · 2013-12-26 · 기능성초미립자공정연구실...

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