conducting polymer

Special Topics on Materials Chemistry材化特論

Part III Conducting polymers

國立清華大學化學系

韓建中教授授課

1

2

2000 Nobel Prize : Conducting Polymers (Since 1977)

Profs. MacDiarmid / Shirakawa / Heeger (Chemist / Polymer Chemist / Physicist)

Conducting Polymers

Polyacetylene

NH( )n

( )n

Polyphenylene

CH CH( )n

Polyphenylene Vinylene

S( )n

Polythiophene

SCH CH( )n

Polythienylene Vinylene

N

R

( )n

Polypyrrole

N

R

CH CH( )n

Polypyrylene Vinylene

O( )nPolyfuran

OCH CH( )n

Polyfurylene Vinylene

Polyaniline( VersiconTM ) 3

Polyaromatics

Polyheteroaromatics

(aromatic + vinyl)

(aromatic + lone pair e)

Key Features of IntrinsicallyConductive Polymers

I. Highly Conjugated BackbonesII. Polymer Backbones need to be ionized (doped) to be conductive

Doping Reaction

n

- e, X

+ e n

X

ConductorInsulator

n

+ e, M

- e n

M

ConductorInsulator

p-type and n-type conductors

Doping by Chemical, Electrochemical, Photochemical meansDoping is Reversible ( 10-11 - 10+3 S/cm )

4

(Charge carriers)

Cations p-type

Anions n-type

(oxidation)

(reduction)

Oxidant : FeCl3, Fe(OTs)3, AsF5, I2, Br2, Cl2 Reductant : RLi, Naph-Li+

Anode : Oxidation Cathode : Reduction

SPECTRUM OF CONDUCTIVIESSPECTRUM OF CONDUCTIVIES

Copper

DopedSilicon

Water

QuartzTeflon

DiamondNylon

105 ohm-1 cm-1

100

10-10

10-15

10-20

10-5

conducting

polymers

5

(S/cm)

• With a very broad conductivity range• Tunable by the degree of doping

Undoped

Fully doped

Partially

doped

Conductivity Spectrum

Metals

ConductivePolymers

ConductiveCarbons

Ionic Salts

ConventionalPolymers

(Nylon, ABS, PC)

High Current

EMI Shielding(Low Current)

Antistats

Insulation

ElectrostaticDissipation

(ESD)

Conductive Materials Applications(electrical)

Conductivity(S/cm)

10+5

100

10-5

10-10

10-15

SurfaceResistance

(Ω/Sq)

(Ω/□)

106-109

109-1011

6

Electrical conduction

• Anti-static

• ESD

• EMI shielding

Electrical field protection

• Cable shielding

• Radar shielding

Chemical potential protection

• Anti-corrosion

Charge storage

• Capacitor

• Rechargeable battery

Semiconductor

• Lithography

• Via-hole electroplating

Sensors

• Chemical sensor

• Bio-sensor

Electronic devices

• Smart window

• Solar cell

• Light emitting diode

• Electrochromic display

• Field effect transistor

• NLO

Miscellaneous application

• Gas separation membrane

• Plastic welding

• Conductive adhesive

• Conductive gasket

Important Potential Applications of Conducting Polymers

7

Application/Property Relationships of Conducting Polymers

Conductivity (charge transport)EMI; ESD; Antistat

Charge storage capability (doping/dedoping)

Battery; Capacitor

Color change (doping/oxidation degree)Smart window; Electrochromic display.

Charge transfer bands (UV-vis-NIR)Solar energy control window; UV-vis stabilizer

Dimension change (doping/dedoping)Electromechanical actuator; Micro-mechanical device

High ionic characteristic (Doped)Exchange/Separation membrane; Virus cleaner

Redox/chemical activity (doping/dedoping/oxidation/reduction)Chemical sensor, Biosensor; Anti-corrosion

Hydrogen bonding (Doped/Some undoped)Microwave/Radar absorbing shield; Plastic welding

Strong intermolecular interactionsHigh strength fiber; Reinforcement materials

ConjugationNLO; Photoconductor; Photoswitch;LED; Thermochromic; Liquid Crystalline

8

Preparation of the First Polyacetylene (PA) Film

HC CH

Ti(OBu)4 / AlEt3 ( 1 : 3.3 )

Toluene / Anisole ( 1 : 3 ) , -78oCn

( 100 um )

Shirakawa and IkedaPolymer J. 1971, 2, 231

Natta, Mazzanti, and CorradiniAtti Accad. Naz. Lincei, Cl. Sci. Fis. Mat. Nat.,Rend. 1958, 25, 3

9

Preparation of PA powder (insoluble) had been reported as early as 1958.

Chlorination reaction of PA had been studied by Shirakawa Observing metallic shining in some cases But did not recognize the connection to its novel conducting behavior

PA film

Preparation of first PA film (insoluble) was reported only after 1971.

Discovery of the First Conducting Polymer

Dopant Conductivity (S/cm)

Cl2

Br2

I2

< 0.05

0.4 - 0.5

30 - 38

Shirakawa, MacDiarmid, Heeger, et. al.J. Chem. Soc. Chem. Commun., 578 (1977)

Polyacetylene

ect.etc.HC CH

Ti(OBu)4 + AlEt3 Doped PolyacetyleneX2

10

Important Historical Aspects and Developments of Conducting Polymers

• Processibility Improvement(New synthetic routes; New processing concepts)

• Conducting Mechanism (Intrachain transport vs Interchain hoping)

• Doping Mechanism (Redox reaction / Non-oxidative protonic acid doping)

• New Functional Dopants (Dopant moiety provides the means for color and solubility modifications)

• Lower Bandgap Polymers (RO-substituted poly(thienylene vinylene); became transparent after doping) • New Properties New Applications

(PLED / FET / Solar Cells)

• Superconducting Polymers? 11

Polyacetylene Polyethylene

*

*

*

etc.

Why π-Conjugated Polymer is a Better Conductor

12

Smaller E

Low energy bondresonanceprocess

Larger E

High energy bond-breakingprocess

-bonding frame keepthe resonance orbitals

to remain within the effective chemical bonding distance

The escape of the vinyl fragments make the reversetransport process impossible

PossiblePolymerization Mechanism of Acetylene(via the metal-carbene intermediate)

13

HC CHWCl6 / Bu4Sn

polyacetyleneacetylene

WCl6 CH3CH2CH2CH2 WCl5

Bu4Sn Bu3SnCl

Bu4Sn

Bu3SnCl

CH3CH2CH2 C

WCl4

H

H

H3CH2CH2CH2C

CH3CH2CH2CH3

"Metal carbene"

C WCl4CH3CH2CH2

H

HC CH

C WLn

H7C3

H

HC CH HC

CH

CH

WLn

H7C3

HC CH

C WLn

C3H7

H

HC CH

C

C

H C3H7

H CH

WLnC

C

H

HHC C

CH

C3H7

WLn

C

H

CH C3H7

H

CC

C

C3H7

H

H

HHC

HC WLn

HC CH

etc.WLn

H

termination

Polyacetylene

InsolubleInfusibleIntractable

metallocyclemetal-carbene

Solubility Improvement of Polyacetylenes (via incorporation of substituents)

RC CHWCl6 etc. etc.

R R R R R

T. Masuda et. al. with improved solubility

WCl6 + C6H5C CH + etc.

PhPhPh

etc.

1 x 200

C. C. Han & T. J. KatzOrganometallics 1982, 1, 1093Organometallics 1985, 4, 2186

Olefin Metathesisring-opening polymerization

WCl6 + PhC CH etc. WLx

PhPhPh

etc.LxW

PhPhPh

PhPh Ph

W

etc.

PhPhPh

WLx

etc.

PhPhPh

WLx

H

14

Coplanarity is the key for gaining high conductivity

Substituent Effects: Solubility Conductivity

15

full overlaping

Coplanarity gives best overlapingbetween orbitals

Distortion from coplanarityreduces the electron mobility

partial overlaping

no overlaping

90o distortion lead to conjugation defects

doped with I2

R R R R R

R = Me, Br, Cl ......... etc.doped with I2; < 0.001 S/cm> 10 S/cm

Steric hindrance effect of substituent is very important

Because,R group destroy the coplanarity of the conjugation system

Reduce electron mobility of intrachain and interchain

16

A Molecular Orbital Description of Stability

• Bonding MO: constructive (in-phase) overlap• Antibonding MO: destructive (out-of-phase) overlap

17

Consider the molecular orbitals of 1,4-pentadiene:

This compound has 4 e, which forming 2 bondsthat are completely separated from one another

4 x 2p

2 x *

2 x

18

The Molecular Orbitals of 1,3-Butadiene

CH2 CH CH CH2 CH2 CH CH CH2 CH2 CH CH CH2

resonance contributors

CH2 CH CH CH2

resonance hybrid

HOMO

LUMOHOMO = the highest occupied MO

LUMO = the lowest unoccupied MO

4 x 2p

19

The Molecular Orbitals of 1,3,5-HexatrieneCH2 CH CH CH CH CH2 CH2 CH CH CH CH CH2

1,3,5-hexatriene resonance hybrid of 1,3,5-hexatriene

20

Summary of Energy Diagram

h h h

Conjugation / Wavelength / Molar Absorptivity

21

1 1 2 2 n's n's

Interaction betweentwo orbitals that havethe same symmetry andenergy level

Formation of anorbital band

£k*

£k

Conducting band(empty orbitals)

Valence band(filled orbitals)

¡µEg Conductivity highersmaller

¡µEg

band gap

Metal (No bandgap)

Semiconductor(Narrow bandgap)

Insulator(Wide bandgap )

,

Metal

Semiconductor/Insulator

22

Bands and Bandgaps

Element SolidsC : insulator (5.5 eV)Si : semiconductive (1.1 eV)Ge : semiconductive (0.7 eV)Sn : metal (0.1 eV)Pb : metal

23

increased attraction(nucleus e cloud)

• Bond dissociation energy (bond strength) : energy required to break a bond or energy released to form a bond

increased repulsion(nucleus nucleus)

Energy diagram for a H-H bond formation

24

Bonding in Hydrogen Halides

Typical Charge Carriers (via doping)

25

soliton

antisoliton

positive soliton

negative soliton

trans-polyacetylene

hole polaron cis-polyacetylene

NN

NH

NN

NNH

Nhole polaron polypyrrole

electron polaron polyphenylene

R

RR

R

R

R

R

RR

R

polydiacetylenehole polaron

SS

SS

SS

SS polythiophenepositive bipolaron

Energy diagramsof charge carriers

26

neutralsoliton

S0

positivesoliton

S+

negativesoliton

S-

neutralpolaron

P0

positivepolaron

P+

negativepolaron

P-

hv1

hv2hv3

positivebipolaron

B++

negativebipolaron

B - -

hv1

hv1

No. of charge carrier absorption bands:

Soliton: 1Polaron: 3

Bipolaron: 2

π band

π* band

Alternative Methods for Making Polyacetylenes

27

Cl Cl Cl Cl Cl - HCl

¡µ

pyrolytic eliminationPVC

poly(vinylchloride) C. S. Marvel et. al. JACS, 61, 3241 ( 1939 )

Cl2Cl

Cl

Cl

Clpoly(1,4-butadiene)

- HCl

KNH2 / NH3 (liq)

East German patent 50, 954 ( 1966 )CA 66 : 86117 r

Cl Cl Cl Cl ClCl

conjugation defects

Both approaches yield poorly conductive polyacetylenes

Dehydrochlorination

Durham Route (via a processable precursor)

28

X XRing-openingolefin metahesispolymerization

X X

n

retro-cyclization

X X

n

I2doping

10 S/cm

+

Cyclization

t1/2 ¡Ü 20 h at 20 oC

very unstabledifficult in handling

10-7 S/cm

¡î too much " stability gain "both products form conjugated systems

(X = -CF3, -COOMe)

Cyclooctatetraene

XC CX

Feast et. al.1. Polymer, 21, 595 ( 1980 )2. J. Phys. Colloq. C3, Suppl. 6, 44 : C3 -148 ( 1983 )3. Polymer, 25, 395 ( 1984 )

X

X

X

X

29

The Diels–Alder Reaction(1,4-addition reaction; concerted reaction)

8.8

7-45.ppt

+

new bond

new bonddiene dienophiletransition

state

a pericyclic reaction; a [4+2] cycloaddition reaction

3 2σ+ 1

30

ROMP

nn

£G

70 oC

stable at RTeasier in handling " less stability gain "

Resonance Energy (Kcal/mol)

3660

Strategy : Stabilize the prepolymer by reducing the stability gain in the conversion step

X X

n

retro-cyclization

X X

nt1/2 20 h at 20 oC)

unstable at RT

For the 2nd ring:24 kcal/mol

Syntheses of Poly(p-phenylene) (PPP)

31

Cl Cl + Nan

+ NaCl Wurtz -Fittig Reaction

G. Gold finger et. al. J. Polym. Sci., 4, 93 ( 1949 )J. Polym. Sci.,16, 589 ( 1955 )

I I

R

+ Cu

R

n

Ullmann reaction

S. Ozasa et. al. Bull. Chem. Soc. Jpn., 53, 2610 ( 1980 )

• Had very low molecular weights or irregular structures

Cl Cl + Na Cl Cl + Na

ClCl Cl + NaCl

NaCl

Cl Cl

or

Cl

Cl Cl

Cl

Reductive polymerization (step-reaction)

32

I I

R

+ Cu I CuI

ROxidativeaddition

I CuI

R

I Cu

R

I

R

+ CuI2

Reductiveelimination

I

R

I

R

etc.

R R

etc.

R RR

33

+ CuCl2 / AlCl3n

P. Kovacic et. al. JACS 85, 454 ( 1963 )

Most successful and economicalOxidizing agent : CuCl2, MnO2, MoCl5, FeCl3Lewis acid catalyst : AlCl3, AlBr3

CuCl2

AlCl3

Cl Al

Cl

ClCl + CuCl

Radicalcation

H

HAlCl4

AlCl3CuCl2

- 2H+2 HAlCl4+CuCl

Use of AlCl3 help reduce the following side-reaction

+ Cl ClH

+ CuCl + Cl- H

CuCl2Cl

Oxidative polymerization (step-reaction)

33

34

n n

Ziegler catalyst

MW = 5000 - 10,000poly(1,3-cyclohexadiene)

450- H2

£G

¢J

chloranilxylene

C. S. Marvel et. al.JACS 81, 448 ( 1959 )J. Polym. Sci. A3,1553 ( 1965 )

aromatization

OCl

ClO

Cl

Cl

p-chloranil

( tetrachloro-1,4-benzoquinone )

Oxidant

n n n( Cl2, Br2 )

300 - 380

- 2 HX- H2

n

- H2

X2 ¢J

£G

X X

-2 HX

Catalyzed Chain polymerization

n n

450 ℃

chloranilxylene aromatization

- H2

n n

300 - 380

- 2 HX- H2

℃X X

35

HO OH HO OHpseudomonas putida

Base

C

O

Cl R

O O CC R

OO

R

R = OCH3, CH3, Ph

( for improving solubility )

O O CC RROO

n radical chainpolymerization

highly soluble ; easily processible

DP = 600-1000 ( degree of polymerization )

220 ℃

n

( t1/2 = 30 sec for R = OMe)

Ballard et. al. JCS, CC 954 ( 1983 )

Lower the aromatization temperature via the decarboxylation

36

Free Radical Chain Reaction

OR

OCORROCO

ROOR

Initiation step

OCORROCOOCORROCO

RO

Propagation steps

RO

R' R' R' R'

( R' = OCOR)

TerminationR' R' R' R'

RO

R' R'n

(X = radical terminator)

X

Radical Chain Polymerization

Mechanism

37

Initiation

Propagation

RO OR 2 RO

RO +X

RO

X

RO

X

+

XRO

X X

ROX X +

XRO

X X X

ROX X X

n

Termination ROX X X

n

+ RO ROX X X

nOR

ROX X X

n

+X X OR

n

XRO

X X X

n

X X X OR

n

Chain transfer ROX X X

n

+ ZR' ROX X X

nZ

+

( Z = H, I, Br, Cl )

ROX X X

n

ROX X X

n

H+

R'

Radical Initiators

38

ROOR 2 RO

H3C C

CH3

CH3

O O C

CH3

CH3

CH3 2 H3C C

CH3

CH3

O100 - 120oC

t-Butyl peroxide

CO

O O C

O 60 - 80oCCO

O2 CO

Omore stable

radicalBenzoyl peroxide

CO

O O C

O

OO CC

CH3

CH3

HH3C

H3CH

Diisopropyl peroxydicarbonate

C

CH3

CH3

O OH

Cumyl hydroperoxide

H2O2 (Hydrogen peroxide)

(H3C)2C N

CN

N C(CH3)2

CN

2 C(CH3)2

CN

+ N N

AIBNAzo bis(isobutyronitrile)

K2S2O8 (Potassium persulfate)

Chain Transfer

TABLE 2.2 Chain Transfer Constants for Selected Solvents at 60oC with Respect

to Polystyrene and Poly(vinyl acetate)

Cs X 104

Solvet Polystyrene Poly(vinyl acetate)

Benzene Toluene Ethylbenzene Isopropylbenzene n-Heptane Acetone Butanone Ethyl acetate Ethyl butyrate Phenol Anilin n-Butyl chloride n-Butyl bromide n-Butyl iodide Methylene chloride Chloroform Carbon tetrachloride Carbon tetrabromide

0.181.256.78.20.424.1 (80 )5.0 (80 )

0.040.061.850.150.5

92

13,600

2.2 21 55 90 17 11 65 2.3 17 (50 )220 (40 )210 10 50800 4140920

39,000

oC

oC

oCoC

Radical stability : 3o > 2o > 1o > methyl

Otheractivated - H ROOH, R S H, R C H,

O

R CH,OR

R

R' CH2

NR2

Allylic

Benzylic

39

HC CH2 CH2 CHa

CH

Styrenepolystyrene chain

stablized by

O C

O

CH3

CH2 CH CH2

OC

O

H3C

CH

OC

O

H3C

a destablized by OAc(more reactive)

CH2

Syntheses of Polyphenylene Vinylene (PPV)

H3C CO

HCH CH

n

(CH3)3C O K

DMF

G. Kossmehl et. al.Makromol. Chem. 182,3419 ( 1981 )

H2C CO

HH

B

H2C CO

H

H

C C

OH

HH

H n

- H2O

CH CHn

C COH

HH

H

Nu

C COH

HH

HC C

OH

HH

H

Nu C C

OH

HH

H

etc.

C COH

HH

HC C

OH

HH

HC C

OH

HH

H

C C

OH

HH

H

C

H

H

etc. etc.

or

40

Witting Condensation

Ph3P CH CH PPh3 + C C

O

HO

HCH CH

n

R. N. McDonald et. al. JACS 82,4669 ( 1960 )G. E. Wnek et. al. Polymer 20,1441 ( 1979 )

Ph3P CH CH PPh3 Ph3P CH C

PPh3

H

C CO

HO

H

Ph3P CH C

PPh3

H

C CO

H

H

OH

Ph3P CH C

Ph3P

H

C CO

H

H

O

Ph3P CH C

H

C CO

H

Hetc. CH C

HCH C

HCH C

Hetc.

Ph3P BrH2C CH2Br

triphenyl phosphine

Ph3P H2C CH2 PPh3

Br Br

Base (like LiBu)

Ph3P HC CH PPh3Ph3P CH CH PPh3Phosphorus ylide (phosphorus-stabilized carbanion)41

Dehalogenation

Cl

Cl3C CCl3

ClCl

Cl- Cl2

Cl

CCl

ClCl

Cl

CCln

M. Ballester et. al. JACS 88, 957 ( 1966 )

McMurry Condensation (TiCl3/LiAlH4)

OHC CHO- "O2"

CH CHn

L. Rajaraman et. al. Curr. Sci. 49 (3), 101 ( 1980 )

C

O

C

O - "O2"C C

n

Feast et. al. Polymer Commum. 24,102 ( 1983 )

42

ClH2C

R

R

CH2ClNaH/DMF

-HClCH CH

n

R

R

( R = H, CH3, OCH3)

H. H. Horhold et. al. Makromol. Chem. 131, 165 ( 1970 )

C C

H

H

C CH

H

H

Cl

H

Cl

H

H

Cl

etc. CH2

HC CH2

Cl

HC

Cl

CH2

HC

Cl

CH CHn

C C

PhPh

N2 N2- N2 C C

Ph Ph

n

Dehydrohalogenation of Benzyl Halides

From Bis(diazobenzylic) Compounds

43

C C

PhPh

carbene intermediate

-HCl

ClH2C CH2Cl + SMe2 H2C CH2Me2S SMe2

ClClbissulfonium salt

NaOH

CH CHn

CH2

HC

nSMe2

Cl

£G

Casting

sulfonium polyelectrolyte

£G

Casting dialysis

-NaCl- low MW molecules

+ NaCl

R. A. Wessling et.al.J. Polym. Sci. Polym. Symp.,72, 55( 1986 )U. S. Patent 3,706, 677 ( 1972 )U. S. Patent 3,401, 152 ( 1968 )

Via Sulfonium Polyeletrolyte Precursor

44

- SMe2

- HCl

C CMe2S SMe2

ClCl

H

H

H

H

NaOH

C CMe2S SMe2

H

H

H

C CSMe2

H

H

H

Cl

quinone dimethane

C CSMe2

H

H

H

Cl

diradical

Initiates the polymerization of quinone dimethane

45

C CSMe2

H

H

H

Cl

Other possible mechanism :

NuC C

SMe2

H

H

H

Nu

C CSMe2

H

H

H

Cl

CH2

HC

nSMe2Cl

H2C CH2 SMe2

ClClCH2

HC

nSMe2

NaOH dialysis

(25 - 35 % yield)Acid titration : > 90 - 95 % NaOH has been consumed.

Why ?

Cl

Me2S

May be :

CH2 S

ClCl

NaOH

Me

Me

a

ba

b

H2C CH S

Me

Me

H2C CH2 S

Cl

Me

MeOH+

non-productive pathway


H2CMe2S

Me2SMe2S

Cl

10.9

A good nucleophile is required Does not require a good nucleophile

A good leaving group is required A good leaving group is required

Polar solvent is not required Polar ionizing solvent is usually required

46

47

A possible solution :

H2C CH2Et2S S

ClCl CH2CH3

CH2CH3

2o C is more hindered, whichreduce the SN2 side reaction

SMe2 SEt2

But a new problem was created ,

CH2 S

ClCl C

Et

NaOH

a

b

ab

CH S

Cl

Et

Et

CH2 S

Cl

Et

H2C+

non-productive pathway

C

H

H

H

H

H

CH2


H2CEt2S

H2CEt2S

H2CEt2S

Relative stabilities of carbanions

carbanion carbanion carbanion anion

: : : : most stable

least stable

Relative stabilities of carbocations

C

R

R

R

> C

R

R

H

C

H

R

H

> C

H

H

H

>

tertiarycarbocation

secondarycarbocation

primarycarbocation

methylcarbocation

least stable

most stable

Relative stabilities of radicals

48

49

S

C

C

S

C

C

even worse !

H

HH

H

HH

HH

HH

C

C

H

H

H

HH

H

S

C

C

HH

HH

C

C

H

C

H

H HC

H

HH

H

H

H

< <Nucleophilicity :

New problems appeared,

CH2ClClH2C + SR2

CH2H2CR2S SR2

ClCl

priceSR2 yield

SMe2 80 %

SEt2 60 %

SPr2 30 %increasedramatically

Why ? and How ?


H2C CH2Pr2S S

ClCl CH2CH2CH3

Pr

2o C, disfavor-H abstraction

2o C, disfavor SN2

SEt2 SPr2

50

S


S

also a stronger Nu

contains only 2o C, which willdisfavor all possible side reactions

1

1'

2 3'

3 2'

CH2ClClH2C + S CH2H2C SS

Cl

> 80% yd

NaOH

CH2

HC

nS

Cl

> 80% yd

cheap !

CH CHn

best quality

C. C. Han et. al. Polymer Communications 28, 261 ( 1987 )J. of Polym. Sci., Polym. Chem. 26, 3241 ( 1988 )

Cl

S works equally well

C. C. Han et. al. J. of Polym. Sci., Polym. Chem. 26, 3241 ( 1988 )

CH2

HC

nSMe2

Cl

CH CHn£G

+ +SMe2 HCl

CH2 CH

SMex

CH CHn-x

doped with AsF510 S/cm

a conjugation defect

CH2

HC

nS

Cl

CH CHn£G

+ + HClS

with less conjugation defect

50 S/cmall 2o C, disfavor SN2

doped with AsF5

CH2

HC

nS

Cl

CH CHn£G

even better

180 S/cm

C. C. Han et. al. J. of Polym. Sci., Polym. Chem. 26, 3241 ( 1988 )

doped with AsF5

51

Material-P38.cdx01/05/38

yield of 1

ClH2C CH2Cl R2SH2C CH2SR2

Cl Cl

NaOHCH2

Cl

HC

SR2

n

-SR2

-HCl

£G

CH CHn

1 2 3

yield of 2

Conductivity of 3

SMe2 ~

S

S ~ S > SEt2 >> SPr2

SMe2 < SEt2 S<

SMe2 SEt2 S< < <

7 15 44 180 S/cm(doped with AsF5)

R.W. Lenz, C.C. Han, J. Stenger-Smith, F.E. KaraszJ. Polym. Sci., Polym. Chem. (1988), 26, 3241-3249

52

Effects of Sulfides on the Synthesis of PPV

“nucleophilicity” “side reactions” “defects”

yield yield

53

Conjugation Length Effectson ionization potential

54

Conjugation Length Effectson ionization / oxidation potentials

55

Conjugation Length Effectson ionization potential and electron affinity

Oxidation Potential

Reduction Potential

4.4 eV

HOMOlevel

LUMOlevel

56

Conjugation Length Effectson band gap

57

Conjugation Length Effectson absorption wavelength

Substituent Effects on the Ionization Potential (eV) (Small Molecules)

Me F F

F F

F6

8.80 9.25 9.30 9.64 10.12

Me F

F5

9.38 9.71 9.74 10.45

CN CN CN CN

PhC CPh < PhC CMe < PhC CH

6.97

8.00 (+0.05) 8.42 8.82

58

59

Substituent Effects on the Ionization Potential (eV)


CF3F3CWCl6 / Me4Sn

CF3F3C

n

n+

CF3F3C

£G

WCl6 / R4Sn

nMetathesis

Ballard

ROCO OCOR ROCO OCOR

n n+ 2RCO2H

£G

Durham

60

Precursor routes for conducting polymers

Ring opening metathesis polymerization (ROMP)(Olefin metathesis polymerization)

Radical chain polymerization

Poly(phenylene vinylene)

ClH2C CH2Cl R2SH2C CH2SR2

Cl Cl

Materia-P36.cdx01/05/28

R2SH2C CHSR2

Cl

NaOH

NaOH

CHH2C

SR2

Cl

CH2

Cl

HC

SR2

n£G

-SR2

-HClCH CH

n

AsF5, FeCl3 (unstable), 10 S cm-1

Orientable, 103 S cm-1Stable Solution

61

PPV via Wessling Route

require strong oxidant

(Dow Chemical route)

Anionic chain polymerization

bissulfonium salt

sulfonium polyeletrolyte


Poly(dialkoxyphenylene vinylene)

OR

RO

OR

RO

ClH2C CH2Cl

OR

RO

R2SH2C CH2SR2

Cl Cl

OH

HO

(OR = OMe, OEt, OBu)

NaOH

SR2 = SMe2 , SEt2

SS

CH2

Cl

HC

SR2

n£G

-SR2

-HClCH CH

n

I2, 50 S cm-1 (Stable)Unorientable Unstable Solution

Gel, Precipitation

OR

RO

OR

RO200 - 250oC

,

62

mild oxidant work fine

Substituent effects: 1. solubility: procesibility, quality of film/coating, application potentials 2. e-effect (donating/withdrawing): HOMO/LUMO, bandgap, coloring, redox, e-density, e-polarizability 3. steric hindrance: chain conformation, packing morphology, e-transport

bissulfonium salt

sulfonium polyeletrolyte

RXNaOH

CH2OHCl SR2


Processible Copolymers

H2C CH2 SS

ClCl

+ r

OR

RO

H2C CH2 SS

ClCl

(1+r) NaOH/H2O

0oC, N2

CH2 CH

S

OR

RO

CH2 CH

S

ClCl

1-x x n

Stable Solution

1.Dialysis

2.Casting3. £G

I2 DopableOrientableStable

CH CH

OR

RO

CH CH1-x x

n

Polymer Communciations 261, 28 (1987)C.C. Han, R.W. Lenz, and F.E. Karasz

good electroluminescent materials

63

++ +

Orientable Copolymers

CH CH

R

R

CH CH1-x x

n

Polymer XDraw Ratio (L/Lo)

Conductivity (Scm-1)

(Doped with I2)

Homopolymers

PPV

PDMPV

Copolymers

(R = OMe)

(R = OEt)

0%

100%

13%

12%

13%

1

14

110

113

1

< 10-5

51

27428

12500

8.3694

Polymer Communciations 261, 28 (1987)C.C. Han, R.W. Lenz, and F.E. Karasz 64

Polymer, 30, 1041 (1989)R. W. Lenz, C. C. Han and M. Lux

CH CH

R

R

CH CH1-x x

n

65

++ +

C


Scheme 1

Fig A

OO

R'

R'OO

R'

R'

O

R'

OH

R'

HO

R'

HO

R'

Fig B

CC

C

H

HC H

HC

Fig C66

e

eElectron transport:Interchain hopping

vsIntrachain moving

CH CH

R

R

CH CH1-x x

n

Polymer X

Conductivity (Scm-1)

(Doped with I2)

PPV

PDMPV

Copolymers

0

1

< 10-5

< 10-5

0.1 0.3

(R = Me)

(R = Me)

67

CH2

HC

S

Cl

n

Gel or Precipitate

3 - 6 Months

CH2

HC

S

Cl

n

OMe

MeO

1 -3 Days

CH2

HC

S

Cl

n

OBu

BuO

1 - 5 Hours

CH2

HC

S

Cl

nS1 - 5 Hours

CH2

HC

S

Cl

nO1 - 5 Hours

68

Electron Donating Groups Promote Elimination

CH

Cl

CH2

SR2RO

OR

CH CH2

RO

OR Cl

SR2+

OR

RO

CH CH SR2+ + HCl

CHnS

SR2

Cl

CH2 CHnO

SR2

Cl

CH2

69

Proposed Mechanism For Precipitation

CH2

Cl

CH

SR2

OMe

MeO

CH CH

OMe

MeO

SR2HCl+ +

CH2 CH

OMe

MeO Cl

Crossing LinkingAggregationLow Aqueous Solubility

Low Aqueous Solubility

¡ì¡ì ¡ì¡ì ¡ì¡ì ¡ì¡ì

70

Stabilization of Polyelectrolyte

CH2

Cl

CH

SR2

OMe

MeOn

H2O

H2O

Py

Precipitates in 1 - 3 Days

Stable Solutionfor 14 + Months

PDMPV

Conductivity (S cm-1)

I2-Doped FeCl3-Doped

Pyridine-Stabilized

Unstabilized

500

50

300

30

C. C. Han, R. L. ElsenbaumerSynth. Met. 1991, 41-43, 849

71

Relative Stabilizing Ability of Amines

N> ~NMe3

N

N>>

N> ~NEt3

OH

OH N

NH3C CH3

N>

N ~

Me Me

>NMe Me

>N

N~

~N Br N

~ ~N

> ~N

N

OH

HONN

OH

OH

>N

N

OH~

N

N

OH

OH

72


CH2

OBu

BuO

CH

S

Cl

n

CH3CN/H2O

BuOH

CH3CN/H2O/Py

BuOH/Py

Precipitates

in 5 hours

Stable solution

for + 14 months

CH2 CH

S

Cl

n

H2O/PyPrecipitates

in 5 hours

Stable solution

for + 14 monthsS

H2O

74


CH2

Cl

CH

SR2

OMe

MeO

n

Py/H2OCH2

Cl

CH

SR2

OMe

MeO

n

Stable SolutionUnstable Film (insoluble)

Py/H2OCH2

Cl

CH

SR2

OMe

MeOx

CH2

Cl

CH

N

OMe

MeOy

Stable Solution

Stable FilmSoluble (H2O, DMF, DMSO, MeOH, EtOH)1HNMR, TGA

75

larger amount

small amount

Non-Ionic Precursor Polymer

76

CH2

OBu

BuO

CH

S

Cl

nCH2

OBu

BuO

CH

OBun

BuOH/Pyridine

Room Temperature

Soluble, StableElastomer, Tg = 2.6oC1HNMR, TGA, GPCC. C. Han, R. L. Elsenbaumer

Mol. Cryst. Liq. Cryst. 1990, 189, 183

Thermal Elimination

CH2

OBu

BuO

CH

OBun

CH

OBu

BuO

CHn

£G

250 - 300oC

I2, 1 Scm-1 Insoluble

77

Non-Thermal Elimination

CH2

OBu

BuO

CH

OBun

CH

OBu

BuO

CH

Soluble

I2, 14 Scm-1

H+ BuOH + H

Butanol Scavengers

CH

OBu

BuO

CH + Butanol Adducts

Butanol Scavengers

Me3SiClMe3SiBrMe3SiIMe2SiCl2(CH3CO)2O(CF3CO)2O

¡ì¡ì ¡ì¡ì ¡ì¡ì ¡ì¡ì

¡ì¡ì ¡ì¡ì

C. C. Han, R. L. ElsenbaumerMol. Cryst. Liq. Cryst. 1990, 189, 183

78

Simultaneous Elimination and Doping

CH2

OBu

BuO

CH

OBun

CH

OBu

BuO

CHn

H+, Solvent

Weak Acid

H+, Solvent

Strong Acid

Neutral Polymer Solution

Doped Polymer Solution


79

Simultaneous Elimination and Doping

CH2

OMe

MeO

CH

OMen

CH2 CH

OMenS

Weak Acid

Strong AcidNeutral Polymer

Doped Polymer

Weak Acid

Strong AcidNeutral Polymer

Doped Polymer

80

Protonic Acid-Doping of Various Conducting PolymersConductong Polymers Dopants Conditions Conductivity Dopong Level

S/cm mol %

Poly(thienylene vinylene) CH3SO3H in CH3NO2, 20h 2.4 8.7 %

_< 10-4neat, 1 day

31.2 %5.3in CH3NO2, 20h¡E

19.7 %44.1 in CH3NO3, 2hCH3SO3HPoly(phenylene vinylene- co-dimethoxyphenylenevinylene) (90:10) _< 10-7neat

19.7 %31.5in CH3NO2, 50h¡E

10.9 %10.7 in CH3NO2, 3 h 15 minCH3SO3HPoly(phenylene vinylene)

_< 10-7neat

_< 10-7 in CH3NO2¡E

C. C. Han, R. L. ElsenbaumerSynth. Met. 1989, 30, 123

CF3COOH

FeCl3 6H2O

CF3COOH

FeCl3 6H2O

CF3COOH

FeCl3 6H2O

81

Protonic Acid-Doping of Poly(dimethoxyphenylene vinylene)

Acids Conditions Conductivity Doping Level

CH3SO3H in CH3NO2, 15 min

S/cm

36.8

mol %

46.1

in CH3NO2, 1 hr 40 min 42 54.0

CF3SO3H

C6H5SO3H

in CH3NO2, 28 min 24

in CH3NO2, 16 hr 25 min 69.4

Neat & in vacuo, 1.5 hr 46 9.3

in CH3NO2, 23 hr

HBF4

CF3COOH

CF3CF2COOH 32

CF3(CF2)2COOH in CH3NO2, 23.5 hr 42

CF3(CF2)6COOH in CH3NO2, 26 hr 71

CH3COOH in CH3NO2 < 10-7

< 10-3CH2ClCOOH in CH3NO2, > 100 hr

CHCl2COOH in CH3NO2, 23 hr 12.1 20.7

CCl3COOH in CH3NO2, 8 hr 18.8 13.1

¡E in CH3NO2, 36 min 105 4.4

C. C. Han, R. L. ElsenbaumerSynth. Met. 1989, 30, 123 82

Proposed Doping Mechanism

OMe

MeO

OMe

MeO

OMe

MeO

OMe

MeO

H

OMe

MeO

OMe

MeO

OMe

MeO

OMe

MeO

HH

HH

Disproportionation

OMe

MeO

OMe

MeO

HH

H H

OMe

MeO

OMe

MeO

Bipolaron13C NMR

Two PolaronsESRUV-vis-NIR

C. C. Han, R. L. ElsenbaumerSynth. Met. 1989, 30, 123

84

Non-thermal Elimination

CH2

OBu

BuO

CH

OBun Partial

Elimination

CH

OBu

BuO

CHm

CH2

OBu

BuO

CH

OBun-m

Soluble, OrientableLiquid Crystalline


85

1. Conventional Liquid Crystalline Polymers

etc. etc.

etc. etc.

RigidPlanar

FlexibleNon-Planar

2. Partially Eliminated Precursor Polymers

CH2

OR

RO

CH

ORj

CH

OR

RO

CHi

86

CH

OR

RO

CHn

+ HXCH

OR

ROn

CH

HX

Doping is very time-consuming, and sometimes almost impossible.

87

Potential Approach for a Doping Free Process

CH

Cl

CH2

SR2RO

OR

+ Latent Dopant

Processing

Non-conductive Articles

Processing

Conductive Articles

Criterions :

¡E High aqueous solubility

¡E No chemical reactivity

¡E Similar solubility

¡E Remains homogeneous distribution

¡E Maintains mechanical strength

88

Concurrent Elimination and Doping

CH2

B

CH

SR2

n

R

R

CH

R

Rn

CH

H

B

CH2

Cl

CH

SR2

n

R

R

Precursor polymer Intermediate Conductive Polymer

Protonic Acid-Doped

B = Halogen, BF4 , PF6 , SbF6 , RSO3 , etc.Ion Exchange

C.C. Han and R.L. ElsenbaumerSynthetic Metals, 30, 123-131 (1989)

HB + R2S

£G

R

R n

- R2S

CH2

Cl

CH

SR2

n

R

R£G

R

R n

- R2S, - HCl

89

Interconversion between Various Redox Forms of Polyaniline

Leucoemeraldine Base

Emeraldine Base

Pernigraniline

HN

HN

HN

HN

n

HN

HN N N

n

N N N Nn

[ Ox ] ( -2e ; -2H+ )(+2e ; +2H+ ) [ Red ]

( +2e ; +2H+ ) [ Red ] [ Ox ] ( -2e ; -2H+ )

Fully Reduced

Fully Oxidized

Half Oxidized

90

91

N NHN

HN

N NHN

HN

H H

N NHN

HN

H H

N NHN

HN

H H

HX

X X

X X

XX

N NHN

HN

H H

N NHN

HN

H H

Protonic Acid Doping of Pani

conducting polymer

Documents

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