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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