hanyang univ. spring 2006 chap 11. non-radical addition polymerization general scheme anionic...

Hanyang Univ.Hanyang Univ.

Spring 2006Chap 11. Non-Radical Addition Polymerization

B-Z + CH2=CHX B-CH2-CH- Z+

X

Initiation:

Propagation:

M- Z+ + M MM- Z+

Termination:

M- Z+ + HT MH + ZT

General Scheme

Anionic Polymerization


Spring 2006

CH LiCH3CH2

CH3

CH2 CH CHCH3CH2

CH3

CH2 CH Li

CH2 CH Li CH2 CH CH2 CH CH2CH Li

CH2 CH Li H OH CH2 CH2 Li OH

Initiation:

Propagation:

Termination:

+

+

+ +

Styrene Polymerization



Spring 2006Anionic Polymerization

• Negative centers repel one another and thus termination by recombination is not possible. An ideal polymerization is “living”, which does not terminate until a terminator is added.

• Initiation is normally very fast relative to propagation and all chains grow simultaneously. This leads to polymers with low polydispersity or monodispersity.

• Theoretically:

nn

w

xM

M 11

• The rate of polymerization for methacrylates and styrenes is high even at -78 oC. This is partly for the high concentration of the anion centers.

• The degree of polymerization

0

0

I

MKxn

• K=1 or 2 depending on initiator used.

Characteristics of an Ideal Anionic Polymerization


Spring 2006

Initiation by Electron Transfer

- .

- .

CH2 CH CH2 CH-.

CH2 CH-.

CH2 CHCH2CH--

+ KTHF

-78 oC

K +

K + + +

2

K +

K +K +K

+

• Polymerization mostly done in THF and not nonpolar solvents like cyclohexane or benzene for the solubility the complex in THF.

• The degree of polymerization is given by

0

02

I

Mxn



Spring 2006

Initiation by Nucleophilic Attack

CH2 CH CH3(CH2)4 CHCH3(CH2)2CH2 Li Li

COOCH3

CH2 C

CH3

N Li N

COOCH3

CH2 C

CH3

Li

THF

-78 oC+

++

THF

-78 oC+ +

• Polymerization can be done in both polar and nonpolar solvents.

• The degree of polymerization is given by

0

0

I

Mxn



Spring 2006

Initiation by Living Polymer

CH2 CH Li CH2 C

CH3

COOCH3

CH2 CH CH2C

CH3

COOCH3

LiTHF

-78 oC++ +

CH2 CHLiCH2 C

CH3

COOCH3

++

Because the starting anion has to be a stronger Lewis base than the resulting anion.

But not

0

0

I

Mxn



Spring 2006

Propagation

M Z M M MZ+-Z+-

Z+- +CovalentBond

Contact IonPair

Solvent SeparatedIon Pair

Free ions

Solvent polarity increases

kP increases

Polymer tacticity decreases

• Kp can vary by orders of magnitude.• The polydispersity remains low because the rate of

inter-conversion between the different forms is much faster than that of polymerization.



Spring 2006

Termination

M MH

M MCOO

MCH2Br CH2Br

MM

MCH2Br CH2Br

M Br

Z+-

By proton

H+

Z+ +

By CO2

Z+- CO2

Z+-

By using a limiting amount of 1,2-dibromoethane

Z+-2

K=2

By using a much excess of 1,2-dibromoethane

Z+-




(1) proton donor H2O or ethanol Strong base is not enough for initiation.

(2)

Ctr,s=10-3 (small chain transfer constant)

EtOH high MW product

ethoxide no longer living.

Strong base is not enough for initiation.

C H 2 C

H

: - + H 2 O C H 2 C H 2 + O H

-

H2O Ctr,s=10H2O low MW polymer No living polymer

CH2 C

H

:- + C2H5OHCH2 CH2

+ C2H5O-



(3) Termination can occurred by hydride elimination without impurities.

a)

b) anionic species(active center) react with chain endsto form inactive allylic anion.

C H 2 C H C H 2 C H : - N a +

C H 2 C H C H C H

+ N a + H - :

C H C H C H 2 C H + C H 2 C H . . -

C H 2 C H 2 + C H C H C H 2 C H . . -

1,3 diphenylallyl anion very unreactive, highly resonance stabilized



Termination of polar monomer

In this case, although initiator or active center attack monomer, that means non-polymerization.

C H 2 C

C H 3

C O C H 3

O

+ R - L i + C H 2 C

C H 3

C R

O

+ C H 3 O - L i +

+ CH2 C

CH3

COOCH3

CH2 C:-CH3

COOCH3

Li+

CH2 C

CH3

COOCH3

C

O

C

CH3

CH2 + Li+CH3O-



Backbiting or intramolecular rexn

4) Hugginson-Wooding System

J.Chem. Soc. 1952

Polymerization of styrene conducted in liq. NH3 at bp -33C

(1) reaction rate ↑ as [I] and [M]2

I=K+NH2- rate ↑ as [NH2

-] ↑ but as [K+] ↓

(2) MW [K+] and [NH2-]

(3) Polymer is formed without unsaturation.

Cyclic trimer at the end of chain

C H 2 C C

O C H 3 O

C C H 3

C O O C H 3

C H 3 C O O C H 3

C H 2 C C

O

C C H 3

C O O C H 3

C H 3 C O O C H 3

+ C H 3 O - - ̈



][

]][[]][[ 2

2

K

KNHMKkMHNkR i

ii

N H 2 - C H C H 2 +

ki H 2 N C H 2 C : -

H

][

]][[

2

2

KNH

NHKk

KNH2 K NH2

k

[K+] 를 가하면 Ri

Dissociation of initiator

Initiation step


Spring 2006

Propagation


]][[ MMkR pp

H 2 N M n - + M H 2 N M n . M

- kp

Termination

][

][][

]][[

][][

3,

22

3,

22

NHk

NHMkk

NHKk

KNHMkkKR

str

pi

str

pip

][

][][

]][[

3,

2

1

222

1

2

1

22

1

NHk

KNHMkKkR

KNHMKkR

str

pip

ii

H 2 N C H 2 C H C H 2 C : - H

+ N H 3 H 2 N C H 2 C H C H 2 C

H

H

: N H 2 - +

ktr,s

n n

Occurs by chain transfer

Rtr=ktr,s[M-][NH3+]Overall Rate using Steady state assumption. (RiRt).

KCl 을 넣으면 ? Rp slow down

[K+]=[NH2-]



][

][

][

][

33, NHC

M

NHk

MkX

sstr

pn

물이 없으면 ,

Chain transfer constant for solvent

molekcalEEEE

rateoverall

RateDPtemp

molekcalEEE

trpiR

n

trpnx

/9

/4

Activati on energy for Xn



1 1

1 n

wn

nn

w

M

MX

XM

M이면이므로

RONa + nCH2 CH2

O

CH2CH2O-Na+RO(CH2CH2O)n- 1

Flory 가 지적하기를

정지반응이 없게 되면 narrow MW distribution 을 얻을 수 있다 .

5) Base Initiated Polymerization

NO2 C O> > SO2 > CO2

>>> CH3CH CH2

CN > SO > C2H5

치환기들이 매우 중요 . 결국 nucleophilic substituents 의 electron withdrowing substituents 가 initiator 들에 가장 반응성이 좋음 .

2-nitropentene 등은 KHCO3 (potassium bicarbonate) 같은 것들에 의해서도 개시됨 .

–NO2 는 매우 e- withdrawing 해서 anion 을 안정화시킴 .



6) Practical Comments

If we use metal as an initiator propagation rate is fast.

purity import!

7) Propagation Kinetics

]][[ MMkR pp

라디칼 중합에 비해 propagation 은 그다지 빠르지 않음 .

많은 living polymer 들에 대해 [M:-] = [I][M] = is about 10-9 to 10-7 molar[M:-] = 10-3 to 10-2 molar

kp for free radical case is 5103 l/molesecKp 는 solvent 와 counter ion 에 dependent!solvent 를 변화 시키므로 해서 counter ion 을 active center 와 분리시킬 수 있다 .rate 상승을 기대 .

conc. of anion = conc. of initiaor



(1) Evaluatation of Individual Propagation Rate Constants

Propagation rate constant for free ion and ion pair. [P-]:conc. of free ion [P-(C+)]: conc. of ion pair

])][([]][[ MCPkMPkR ppp

2

1

)])([(][

][][

]][[

)]([1

)(

]][[][

)]([][

CPKP

CP ion

CP

CP

K

CPKCP .Eqat

MMkRM

CPkPkk app

pppapp

p

첨가하면더을만약



* How to measure kp, kp, K ?

][

log 0

MC

C

.apppkslope

appk

2

1

][ M

p

pp

kintercept

Kkkslope 2

1

)(

t



][

][][

C

MKP

][][

][CZ

MKP

Conc. of living and conc. of free ion

][][

][)]([CZ

MKMCP

A salt that must be soluble in THF with common ion to gegen ion is added to reaction mixture.

[C+][CZ]

At high added salt conc.

Conc. of added salt is [CZ]

][

)(

CZ

Kkkkk pp

pappp

][

)]([][

M

CPkPkk

originally

pappp

apppk

][CZ

p

pp

k

Kkkslope

int

)(

Now

Then able to get kp-, kp

, K from two graphs.



Effect of gegen ion on Anionic Polymerization of Styrene

THF Dioxane

kp K107 kp

- kp

Li+ 160 2.2 6.5104 0.94

Na+ 80 1.5 3.4

K+ 60~80 0.8 19.8

Rb+ 50~80 0.1 21.5

CS+ 22 0.02 24.5

- Why kp- is the same value?; kp- is much more larger than kp Thus we can say that reactivity of free ion is much greater than that of ion pairs.

- In the case of dioxane?;In dioxane which is not tend to be solvating it has reverse tendency compared to the case of THF. Solvation is not important in dioxane. Cs is too big that there is no difference. Explanation is that there is not so solvating power of Cs



]][[

]][:[

MRLikR

MLiMkR

ii

pp

Look at difference.Unassociated species

Li+ genenion in aromatic hydrocarbon

Let’s say we are using BuLi initiator.

결국 solvation as well as is important!

1,2 diethoxyethane 은 을 낮추게 되지만 highly solvating ether 이므로 kp varies 1~1000 fold. Sty in THF, free ion 의 역할이 큼 . Reactivity of free ion 이 ion pair 의 reactivity 보다 큼 .

In aromatic hydrocarbonUnassociated species dominate rate. 이전의 경우는 free ion 이 속도를 결정했으나 이 경우는 unassociated species 만이 속도를 결정한다 . (very low conc.)

(nC4H9Li)6 C4H9Li6

K1

(R Mn-Li+)2 2C4H9 Mn-Li+K2

CH2 C

H

RLi

LiCH

RCH2 2 CH2 CLi

H

RCovalent character



6

1

6946

1

1 ])[(][ LiHCKRLi

rateinitiationinorder

Rtheinorder

LiMKLiM

R i

6

12

1

2

1

22

1

2

6

1

]):[(]:[

][

Evidence — viscosity measurement before and after term we find that living

polymer is associated after termination, viscosity drops.

고분자 혼합물에 개시제를 가하면 Ri 는 1/6 승에 비례하게 된다 .

Aliphatic HC 내에서의 중합반응은 aromatic HC 내에서 보다 훨씬 낮다 .

왜냐하면 개시제와 ion pair 들의 dissociation 이 적어지기 때문 .


Spring 2006

Effect of solvent and gengenion on Copolymerization of Styrene and isoprene at 25 C

Solvent% Styrene in copolymer

Na+ counter ion Li+ counter ion

Nonsolvent 66 15

Benzene 66 15

Triethyl ether 77 59

Ethyl ether 75 68

THF(highly saturating solvent)

80 80

일반적으로 sodium이 lithium 보다 더 ionic 함

@ Li+ 이 Na+ 보다 active center 에 더욱 tight 하게 결합되어 있음 . Solvating solvent 는 Li+ 의 경우는 변화 시키고 부분적으로 ionic 한 Na+ 은 많이 변화 시키지 못한다 .

Lenz P.437 Table 13-9




St-MMA System

1) Li Metal Initiator 를 쓸 경우 고분자 생성물에 Styrene 이 많이 포함 .2) BuLi 개시제를 쓰면 Styrene 이 거의 없음 .

Old Explanation

1)Radical anion mechanism 으로 설명2)Li metal 을 사용하면 MMA 와 Styrene 이 중합3)MMA 는 anion 으로 형성4)Styrene 은 radical 이 형성되어

New Explanation Overberger, 1966

NMR 을 사용 , styrene block 을 발견Radical 은 발견못함처음에 styrene block 이 형성 , MMA 블록은 나중에중합초기에 Li counterion 이 Li metal 에 용해 , 중합이 homogeneous 하게 진행된다 .

MMM SS MSMMS MS MMM SS M



CH=CH2

C=O

OMe

C

CH3

CH2

Li

즉 styrene 이 Li particle 과 associated 됨 .

St 이 MMA 를 Li 에 못가게끔 blocked out 시킴 . Sty 이 표면에 강하게 흡착된 후 고분자가 선택적으로 형성

성장사슬이 점차 medium 인 (solution) 에 용해되어 결국 Li particle 을 뚫고 나와서 solution 으로 나옴 .

Li soluble


Spring 2006Cationic Polymerization

C CH2

H3C

H3C CH2 CH

OCH2CH3

proton donorelectron acceptor

δ- δ-

Positively charged active center 에서 중합반응이 일어남alkene 류의 모노머에서 중합이 일어나는 경우 electron donating 치환기를 갖는다 .

예 )

isobutylene ethylvinyl ether

1. protonic acids : HCl, H2SO4, HClO4, Cl3CCOOH 2. Lewis acids : BF3, AlCl3, TiCl4, SnBr4, SbCl3, BiCl3

Initiators– 주로 Acids

B

F

F

F

C2H5Cl C2H5 [BF3Cl]+. .

. .: +

C2H5 [BF3Cl] + C2H5 CH2 CH [BF3Cl]

R

CH2 CH

R

+ ++ .

이 경우를 cationogen 이라 함

Electron donating group

* Lewis acid 는 개시제로 효과적으로 사용되기 위해 coinitiator( 공촉매 ) 를 사용한다 .

chloroethane



OH

BF3OH H++ C C

C

C

CH3 C+

C

C

B F3OH

isobutylene

BF3 + OH2 BF3OH H+k e

CH3 C C C C+BF3O H + C C

C

C

kp

Typical Initiator Systems Co-initiator Initiator SnCl4 H2O AlCl3 HCl H2SO4 H2SO4

Order of reactivity AlCl3 > AlRCl2 > AlR2Cl >AlR3 물이 있고 공기중에서 spill 하면 불남

HCl > CH3COOH > C6H5NO2 > > H2O >> CH3OH > CH3COCH3

Ex)

More acidic initiators are most effective in initiating polymerization


Spring 2006

Termination

Kinetics

Cationic Polymerization

Second order 이므로 반응이 매우 빠름 2 *

3

*

2t

eipp M BFOH

k

KkkR

C C C

C

B F3OH

C

C

C

+ HB-F3OH

H

32ei3ii BF OH MKkHOFBH MkR

OHBF MkR 3pp

S SRR ti 32ei3tt BF OH MKkOHBF kR

32t

ei3 BFOHM

k

KkOHBF

문제 : 정지반응이 random 하게 일어난다 .

* 가 recipe 임 , 반응을 조절할 수 있음



MXkconstXk ntrnt 0,. 0 이면이면

Mkk

MkX

trt

pn

만약

C1

C3

C 6

C7

C8

C15

C16

B17

F3OHk tr

C21

C22

C27

C30 C 32

C33

C34

B F3OH+

M k k

M k

RR

RX

trt

p

trt

pn



1) Ring opening polymerization

(1) Mechanism

carbon type polymzn. 이러한 ROP 를 할 수 있는 monomer 들로는 cyclic amides, sulfides, acetals, esters, lactam, alkanes, …

(2) 중합가능성

Polymerizability 는 안정하지 않은 ring 또는 쉽게 cyclize 하지 않는 ring 이 잘 됨 .3,4 and 7-11 membered ring 이 가장 reactive 하다 . 5,6 membered rings are stable

and slow 중합 . 그러나 중합은 가능함 .3-membered ring most easily polymerize

O R CH2 OCH2

R

O

CH2

ROORCH2ORCH2

CH2

R

++

+. .. .



(3) THF(Polytetrahydrofuran) 의 중합예

PF52 PF4 (PF6)+ -

PF4 (PF6)+ - + O PF4 O

+PF6

-

gegenion

O(CH2)4O(CH2)4 O(CH2)4

(CH2)4

+-

AO

O(CH2)4O(CH2)4O(CH2)4

+O (CH2)4

+

-A

cocatalyst 로 H2O 가 존재하면 중합속도를 증가시킴 .living polymrization 이 가능하나 termination 이나 transfer 도 일어남 .

O (CH2)4 O+

-A+ O

(CH2)4

(CH2)4



(4)Kinetics

I + ZY K Y+(IZ)

-

initiator coinitiator

Y+(IZ)

-+ M

ki YM+(IZ)

-

nM O+

+ O Mn O (CH2)4O

CH2 C+

H

R

[SnCl4OH]- + CH2 CH

Rstrong initiator

CH2CHCH2

R

]][][[]][)([ MZYIKkMIZYkR iii

]][[ MMkR pp

Initiation

예 ) styrene, stannic-chloride-H2O System [SnCl4OH-]H+

Propagation – can have a low activation energy and be rapid

or

Simple propagation reaction

Overall rate of polymerization may actually increase w/ decreasing temperature, means that termination has a high activation energy.

hanyang univ. spring 2006 chap 11. non-radical addition polymerization general scheme anionic...

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