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o ymer yn es sCHEM 421

Reading (Odian Book):

Chapter 2-1, 2-2, 2-4

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Step Growth Polymerizations

• Bifunctionalmonomer

• !B monomer

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Example Polymers via StepGrowth Reactions

DacronM! Mylar M

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"mportance o# E$%al Reactivity

" !# $ % of ! group at the &eginning

" ! $ % of ! group at an' gien time

!B * !B * !B * !B * !B * !B * !B * !B * !B !B *

!&aB * !B * !B !&aB * !&aB * !&aB *

p $ conerion $ 1 + " ! " !#

n $ aerage degree of pol'meri.ation

$ 1 + (/ 10)

n $ total % of molecule preent initiall'

total % of molecule preent at time t

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"mportance o# E$%al Reactivity

p $ 00 n $ 1

!B * !B * !B * !B * !B * !B * !B * !B * !B !B *

!&aB * !B * !B !&aB * !&aB * !&aB *

!&a&a&aB * !B !&a&aB * !&aB *

!&a&a&aB * !B !&a&a&a&aB *

!&a&a&aB * !&a&a&a&a&aB

p $ 04 n $ 1/

p $ 0/ n $ 23

p $ 0 n $

p $ 05 n $ 3

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M& an' Conversion

6ien that:789 $ 7890 - 7890 p

Reriting:

789 $ 7890 (1 + p)

1

(1 + p)

$

Reriting:

1 7890

(1 + p) 789 $

;noing:

7890

789 n

$n

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• Conerion n

+ 30< 2

+ 50< 3

+ =0< 10

+ =3< 20

+ ==< 100

+ ==3< 200

$ 1

(1 + p) n

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&ei(ht )vera(e an' *%m+er )vera(eMolar Masses

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,actors "nvolve' in the Synthesis o# Hi(h M&-inear Polymers via Step.Growth Reactions

• >igh purit' monomer

• ?i-functionalit'

• @roper toichiometr'

• Aer' high conerion• o ide reaction

• !ccei&ilit' of mutuall' reacting group

• n general: + Duita&le for &ulk reaction

+ 8oderate icoit' during much of the reaction

+ ncredi&le effort (EE) goe to puhing the reaction forard in lat

tage

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Metho's #or Polyester Synthesis

• ?irect reaction

• !cid halide h'droF'l

• Graneterification

• 8elt acidol'i

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Direct Reaction

• HIe ChatelierJ @rincipleK

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Mechanism

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/verall Reaction

• Delf-catal'.ed

Rp 7O>9 7COO>9 7COO>9

• Catal'.ed &' added acid ( 7>*9 $ contant)

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E$%ili+ri%m Consi'erations0Close' System

• nitial h'droF'l and car&oF'l concentration are 7890

• Concentration of eter group L eMuili&rium i p 7890

here p $ eFtent of reaction L eMuili&rium

• Ghe concentration of h'droF'l and car&oF'l group L eMuili&rium muttherefore &e:

( 7890 + p 7890)

• Gherefore

ester H2/

RC//H R/H

3e$ 55555555

6 p M782

( 7890 + p 7890)23e$ 55555555

p2 M72

78902 ( 1+ p )2 55555555

p2

( 1+ p )2 5555

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E$%ili+ri%m Consi'erations0Close' System

• Dole for p 'ield:

• ;noing that:

ester H2/

RC//H R/H

3e$ 55555555

39

1* ;N p 5555

$ 1

(1 + p)

n

1 * ;N $n

E## t # E ili+ i C t t : ;

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E##ect o# E$%ili+ri%m Constant on :p;an' De(ree o# Polymerization0

Close' System

E## t # E ili+ i C t t : ;

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E##ect o# E$%ili+ri%m Constant on :p;an' De(ree o# Polymerization0

Close' System

• ndicate the limitation impoed &' eMuili&rium on the 'ntheiof high 8 pol'mer

+ L n $ 100 (correponding to 8n P 10k) can &e o&tained ina cloed 'tem onl' if ; i 104QQQ

+ Can not &e done in a cloed 'tem for mot pol'mer

• Gherefore mut drie the eMuili&rium

@ol'mer ;

@ol'eter 1 - 10

@ol'car&onate 13Graneterification 01 + 10

@ol'amidation 102 - 10

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/pen System

• SFtent to hich one mut drie the 'tem in theforard reaction + can &e een &' calculating the loering of the mall molecule

condenate concentration that i necear' to achiee a particular 8

+ ;noing that

+ Dole for 7>2O9

6 p M782

( 7890 + p 7890)2

3e$ 55555555p H2/

7890 ( 1+ p )2

555555

H2/ p M7 $ 1

(1 + p) n

p H2/ 6

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Drive the E$%ili+ri%m

• eed to remoe the mall moleculecondenate

+>2O

+>Cl• Dmall molecule condenate need to

diffue through and eentuall' out of thereaction miFture

+ot ea' &ecaue of high icoit'

+Can lead to reaction &ecoming diffuioncontrolled

E## t # & t C t ti

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E##ect o# &ater Concentration onDe(ree o# Polymerization0

/pen! Driven System

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How +est to 'rive theE$%ili+ri%m=

• 8iFing i energ' and capital intenie

+iped film reactor to increae urface area

• ncreae diffuiit' of the condenate +Raie the temperature to loer the icoit'

of the melt

T @otential for ide reaction

+Dell the melt ith olent

T Dupercritical CO2

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