1. Chapter 6 Chain Copolymerization
: Don’t be confused with the Step Polymerization
→ not copolymerization
Chain Coplymerization
: Chain Polymerization in which two monomers are simultaneously polymerized, producing copolymer
Multi-component Coplymerization : Three or more monomers
Terpolymerization : Three monomers

2. Alternating Copolymer
6-1 General Considerations
6-1a Importance of Chain Copolymerization
① Reactivity of monomers
⇒ from copolymerization studies
② To tailor-make a polymer product
not by homopolymerization ⇒ ∵ one product
ex) PS : 8 million PS related product
1/3 ~ homo 2/3 ~ copolymer (SAN, ABS, …)
6-1b Types of Copolymers
Random,
Alternating Copolymer
Block Copolymer
Graft Copolymer

3. 6-2 Copolymer Composition
6-2a Terminal Model; Monomer Reactivity Ratios
The instantaneous copolymer composition—the composition of the copolymer formed at very low conversions (about <5%)—is usually different from the comonomer feed composition because different monomers have differing tendencies to undergo copolymerization.
homopropagation or self-propagation
cross-propagation or crossover reaction
cross-propagation or crossover reaction
homopropagation or self-propagation
where k12 is the rate constant for a propagating chain ending in M1 adding to monomer M2, and so on.

4. Monomer M1 disappears by Reactions 6-2 and 6-4, while monomer M2 disappears by Reactions 6-3 and 6-5.
To satisfy the steady state assumption
This equation can be rearranged and combined with Eq. 6-8 to yield

5. f1 & f2 : mole fraction of monomer M1 & M2 in the feed
F1 & F2 : mole fraction of monomer M1 & M2 in the copolymer
If we know the feed ratios (f) and the reactivity ratios (r), then we can obtained the copolymer composition !

6. 6-2b Statistical Derivation of Copolymerization Equation
and
Divided by [M1*] and k12 +
Using the same method

7. =

8. 6-2 Copolymer Composition
6-2c Range of Applicability of Copolymerization Equation
r1 & r2 for St (M1) & MMA (M2)
Radical : r1 = r2 = 0.46
Electron-withdrawing group
stabilize anionic species
∴ MMA ~ higher reactivity
for anionic polymerization !
Cationic : r1 = r2 = 0.1
Anionic : r1 = r2 = 6
Ionic copolymerization
~ high selectivity, but limitation in practical use
Radical copolymerization
~ almost all monomers, wide range of products

9. 6-2d Types of Copolymerization Behavior
6-2d-1 Ideal Copolymerization: r1 r2 = 1
r1= r2 = 1 : two monomers show equal reactivity → Random
r1 > 1 : M1 is richer in the copolymer
r1 < 1 : M1 is poorer in the copolymer
Number indicates r1 : r1 , F1 
⇒ It becomes more difficult to produce copolymers containing both monomeric units at the difference of r1 & r2 increases
r1 r2 = 1

10. 6-2d Types of Copolymerization Behavior
6-2d-2 Alternating Copolymerization: r1 = r2 = 0
Perfect alternation occurs when r1 and r2 are both zero.
⇒ M1* always react with M & M2* always react with M1
The tendency toward alternation and the tendency away from ideal behavior increases as r1 and r2 become progressively less than unity.
Ideal Copolymerization: r1 r2 = 1

11. * consecutive homopolymerization
* Azeotropic copolymerization
⇒ the copolymer and the feed compositions are the same
∴ d[M1]/d[M2] = [M1]/[M2]
from and
* consecutive homopolymerization
Monomer M1 tends to homopolymerize until it is consumed; monomer M2 will subsequently homopolymerize. Ex) styrene-vinyl acetate with monomer reactivity ratios of 55 and 0.01
Block Copolymerization
r1 > 1, r2 > 1

12. 6-2e Variation of Copolymer Composition with Conversion
Until now instantaneous copolymer composition
→ at low degree of conversion (<5%)
→ cannot be applied to the true systems
* ∴ We need the composition at a function of conversion
Copolymer composition as a function of conversion
M moles of the two monomers
Copolymer formed is richer in monomer M1 (i.e., F1 > f1)
When d M moles of monomers are copolymerized, the copolymer has F1d M moles of monomer 1, and the feed will contain moles
of monomer 1.
A material balance for monomer 1

13. integral form
F1 varies with time because f1 varies
styrene (M1)-methyl methacrylate (M2) with (f1)0 = 0.80, (f2)0 = 0.20 and r1 = 0.53, r2 = 0.56.

14. Dependence of the instantaneous copolymer composition F1 on the initial comonomer feed composition f1 and the percent conversion for styrene (M1) and 2-vinylthiophene (M2) with r1 = 0.35 and r2 = 3.10.
Distribution of copolymer composition at 100% conversion for styrene and 2 vinylthiophene at the indicated values of mole fraction styrene in the initial comonomer feed.

15. Dependence of the instantaneous copolymer composition F1 on the initial comonomer feed composition f1 and the percent conversion for styrene (M1) and diethyl fumarate (M2) with r1 = 0.30 and r2 = 0.07.
copolymer composition at 100% conversion for styrene–diethyl fumarate

16.  >  >     Co-Polymers from FRP Reactivity Three monomer
r > r > r
Co-Polymers from FRP
Reaction time
Reaction time
~ life time of radical : Seconds

17. Polymerization Methods
Mechanism of FRP
Mechanism of LRP
I → 2R`·
Initiation
R-Z R Z →
R`· + M → R1·
Reactive radical
Stable radical
R1· + M → R2·
Propagation
Rn· + M → Rn+1·
Minimize
RMn
Propagating radical
Transfer
Rn· + YZ → Rn+1Y + Z· → →
Termination
Rn· + Rm· → Pn+m
Irreversible
termination
RMn-Z
Rn· + Rm· → Pn + Pm
Dormant species
This shows the differences between the free radical polymerization and the living radical polymerization. In the free radical polymerization. In the free radical polymerization. Radicals are generated in the initiation step then they reacted with monomers within a few seconds and polymers are obtained. During the time another radicals are generated and then polymers are obtained this cycles, initiation propagation termionation keep going until either all the inintiator or monomers are consumed. In the living radical polymerizaztion, radicals are always alive because of the Z capping agent, this is not a chain mechanism. Radicals are here due to this reversible process and polymerization goes until all the monomers are consumed.
Growth time of a polymer chain
~ Hours
Polymerization restart
~ Seconds
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18. Growth time of a polymer chain
Mechanism of FRP
Mechanism of LRP
I → 2R`·
R-Z R Z →
Initiation
Time
M.W.
R`· + M → R1·
Time
M.W.
Reactive radical
Stable radical
R1· + M → R2·
Propagation
[M]/[I], concentration,
temperature, etc.
Rn· + M → Rn+1·
Minimize
RMn
Propagating radical
Transfer
Rn· + YZ → Rn+1Y + Z· → →
Termination
Rn· + Rm· → Pn+m
Irreversible
termination
RMn-Z
Rn· + Rm· → Pn + Pm
Dormant species
This differences of the mechnism gives huge differences in the molecular weigh and structures of the polymers. In the free radical chain polymerization since polymers are obtained with a few second in the early stage of polymerization there are high concentration of monomers so high molecular weigh polymers is obtained, while at the later stage since monomer concentration is low then in the chain cycle only low molecular weigh polymers are obtained. So the resulting polymers are mixture of small and large molecules. While in the living polymerization polymers are keep growing, and radicals are keep a live through the polymeriztion so molecular weight increase with time at the later stage of polymerization since not much monomers are left chain growin just slow down.
[M]/[chain number]
conversion (rxn time)
Growth time of a polymer chain
~ Hours
Polymerization restart
~ Seconds
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19.  >  >     Polymers from FRP Polymer from LRP
Reactivity
Three monomer
  
Polymers from FRP
Polymer from LRP
Reaction time
This figure show the schematic diagram showing the copolymerizarion of three monomers having different reactivity. This is the most common situation of the polymerization to obtain ArF Photoresit polymers. In the free radical polymerization, since the polymers are obtained in a few second the polymers obtained in the early stage of polymerization have only more reactive monomeric units. Then polymers having mostly medium reactive monomers here the red one is obtained. Polymers obtained at the later stage of the polymerization will have the least reactive units. However in the living polymerization since the radicals are alive through out the polymerization and reactivity is lower polymer grows slowly while the resulting polymers have all the component more uniform in size and composition.
More homogeneous
on size and composition
~ Seconds
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POLYMER CHEMISTRY LAB.
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20.  >  >     Chain growth in FRP Chain growth in LRP
Reactivity
Three monomer
  
Chain growth in FRP
Chain growth in LRP
Time
M.W.
Reaction time
This two graph I showed before explains this picture very well. Polymer obtained at the early stage has larger molecular weight in the free radical polymerization. In the living radical polymerization molecular weight keep growing. →
Time
M.W.
More homogeneous
on size and composition
Growth time of a polymer chain
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21. Reversible termination
Polymerization Methods
Types of LRP
ATRP
SFRP
RAFT
Living method
Reversible termination
Reversible addition- transfer
Advantages
Commercial initiator, catalyst, and ligand.
Various monomers
No metal residue
Versatility to various monomers
Disdavantages
Metal containing polymer
Color of metal oxide
Limited monomers
Synthesis of initiator
Synthesis of CTA
Odor of CTAs and color of polymers
So I am sure that at least theoritically living radical polymerization can produce polymers have more uniforn sizes and composition. The I have choose the proper type of living racial polymerization. These three types ATRP, SFRP, and RAFT are the most commonly used living radical polymerizations to prepare polymers by polymer chemists like me. We used RAFT because ATRP used normally metallic ions, the polymers contain metallic ions which is not desirable for the photo resist, SFRP cannot be used for the polymerization of acrylic monomers. So we used
RAFT technique
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POLYMER CHEMISTRY LAB.
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22. Very tough ! r1 and r2 for M1 and M2
6-2f Experimental Evaluation of Monomer Reactivity Ratios
⇒ Using IR, UV, NMR or for monomer HPLC, GC
For polymerization of M1, M2 (M1/M2 is known), γ (from the chemical analysis polymer) can be obtained, then r1 and r2 linear plots can be obtained
→ many experiments
→ r2 ~ plotted as a function of various assumed values of r1
r1 and r2 for M1 and M2
Very tough !
Q-e scheme was developed!

23. 6-2g Microstructure of Copolymers
6-2g-1 Sequence Length Distribution
: mole fraction forming x·M1 units in copolymer
: mole fraction forming x·M2 units in copolymer
… M1 M1 M1 M1 M2 …
P11 = R11 / (R11+R12) →
P P12
ex) *if r1 = r2 = 1, f1 = f2, ideal polymerization,
mostly M1 has one unit

24. ex) * if r1 = r2 = 0.1, f1 = f2,
mostly have x = 1
ex) if r1 = 5, r2 = 0.2, f1 = f2,
M1 ⇒ has large portion of longer units
M2 ⇒ mostly x = 1

25. 6-2h Multi-component Copolymerization

26. Steady-state assumption for M1∙, M2∙, M3∙ = const
(M1∙ consumed = M1∙ generated)
(M2∙ consumed = M2∙ generated)
(M3∙ consumed = M3∙ generated)
Terpolymer composition If

28. 6-3a Effect of Reaction Conditions
6-3a-1 Reaction Medium
Solubility : r1 & r2 affected by reaction medium
ex) bulk, emulsion, suspension, solvent
M1 = MMA, M2 = N-vinyl carbazole
in benzene, r1 = 1.80, r2 = (copolymer is soluble)
in MeOH, r1 = 0.57, r2 = (copolymer is microheterogeneous;
N-vinyl carbazole is located
preferentially around the copolymer
propagating chain)
Viscosity : M1(St) & M2(MMA) ~ bulk; less styrene
(St has less mobility in the viscous medium)

29. Pressure pH M1 = acrylic acid, M2 = acrylamide
pH = 2 ; r1 = 0.90, r2 = 0.25
pH = 9 ; r1 = 0.30, r2 = 0.95
∵ acrylic acid at pH = 9 ⇒ acrylate ion (salt form) ~ lower reactivity
due to the repulsion
Polarity
M1 = polar monomer, M2 = non-polar monomer
in polar solvent, r1↓ & r2↑ (compared to bulk)
∵ high solubility of polar monomer in polar solvent
Pressure
P↑ ⇒ radical polymerization rate↑
ΔV11 - ΔV12 is small ⇒ r is not sensitive to pressure

30. 6-3a-2 Temperature
⇒ r1 & r2 are relatively insensitive to temperature
r1 and r2
Ex) styrene-1,3-butadiene and at 5 oC
and at 45 oC
styrene–methyl methacrylate and at 60 o
and at 131oC.
∵ E (act. E) of radical propagation is small
(radical is very reactive ~ don’t need much E)
E12-E11 ; even smaller than 10 Kcal/mol
cf) initiation ⇒ generation of radical ~ need large E
※ T↑ ⇒ r → 1 ; selectivity↓

31. 6-3b Reactivity Monomer reactivity,
~ the reactivity of M2 monomers toward M1∙ radical
If 1/r1 = 1, then M1 and M2 monomers have the same reactivity toward the M1* radical
If 1/r1 > 1, then M2 monomer have higher reactivity than M1 toward the M1* radical
For each polymer radical, monomer reactivity can be compared in each vertical column (Table 6-2)

32. M1

33. M1

34. M1
6-3b Reactivity

35. ~ the reactivity of M2 monomers toward M1∙ radical
Monomer reactivity
Monomer reactivity,
the reactivities of the different monomers toward the butadiene radical
~ the reactivity of M2 monomers toward M1∙ radical
the data can be compared only in each vertical column.
each horizontal row cannot be compared

36. 6-3b-1 Resonance Effects Monomer reactivity
Methyl methacrylate
Polymer radical
Monomer reactivity of CH2=CH-Y
Monomer reactivity
* Resonance stabilization↑ ⇒ monomer reactivity↑
∵ Resulting radicals are more stable

37. - Radical reactivity; resonance stabilization↑ ⇒ radical reactivity↓
Monomer reactivity
radical reactivity
The order of substituents in enhancing radical reactivity is the opposite of their order in enhancing monomer reactivity:
- Radical reactivity; resonance stabilization↑ ⇒ radical reactivity↓
- vinyl acetate radical is about 100–1000 times more reactive than styrene radical
- styrene monomer is only 50–100 times more reactive than vinyl acetate monomer
self-propagation rate constants (kp) for vinyl acetate is about 16 times that of styrene

38. activation E : solid-line arrows heats of reaction broken-line
four possible reactions
s : the presence a substituent of resonance stabilization
Ex) Vinyl acetate and styrene monomers : M and Ms,
vinyl acetate and styrene radicals : R∙ and Rs∙
reaction
the order of reaction rate constants :
order of activation energies is the exact opposite

39. 6-3b-2 Steric Effects
2nd substituent in 1 position increase reactivity
2nd substituent in 2 position decrease reactivity
Cis is less reactive than trans; transition state of xis is less stable
Monomer reactivity

40. 6-3b-3 Alternation; Polar Effects and Complex Participation
If r1∙r2 = 1 ⇒ ideal copolymerization
If r1∙r2 = 0 ⇒ alternating copolymerization
Electron donating
Electron withdrawing

41. Copolymerization of stilbene and maleic anhydride takes place
* How to make alternating copolymer
⇒ monomer with EDG + monomer with EWG
ex) maleic anhydride, diethyl fumarate, fumaronitrile (with two electron withdrawing groups in 1,2 positions
; no homopolymerization
; readily form alternating copolymer with
styrene, vinyl ether, N-vinyl carbazole (EDG)
Copolymerization of stilbene and maleic anhydride takes place
( no homopolymerization )

42. * Addition of Lewis acid (ZnCl2, R2AlCl, AlR1.5Cl1.5)
increase the tendency to form alternating copolymer
ex) AN, MA, MMA, methyl vinyl ketone ; e- - acceptor monomer
+ propylene, isobutylene, VC, vinylidene chloride ; e- - donor monomer
⇒ without Lewis acid, no alternation!
* (Lewis acid + e- - acceptor monomer)
increase the electron accepting property

43. Two mechanisms have been proposed to explain the strong alternation tendency between electron-acceptor and electron-donor monomers.
① Polar effects in chain transfer
② Homopolymerization of 1:1 complex

44. reference Q = 1, e = -0.80 for styrene
6-3b-4 Q-e Scheme
Obtaining r1 & r2 ~ very tedious)
Q–e scheme by Alfrey and Price ∴
P & Q ; intrinsic reactivity of M1· radical & M2 monomer
e1 & e2 ; polar property of M1· radical & M2 monomer
Then,
reference Q = 1, e = for styrene
r1, r2 can be theoretically calculated without experiments
- not very accurate, but quite reasonable
∵ Steric factor is not considered!

46. 6-3b-5 Patterns of Reactivity Scheme
The ‘‘patterns of reactivity’’ scheme is a more advanced treatment of copolymerization behavior than the Q-e scheme.
The monomer reactivity ratio for monomer 1, r12 :
Since styrene has very little polar character, r1s measures the intrinsic reactivity of M1 radical.
where r1A is the monomer reactivity ratio for copolymerization of monomer 1 with
acrylonitrile, the polar monomer
Therefore the polarity of M1 radical is related to the ratio of the radical’s reactivity
toward the polar acrylonitrile compared to the nonpolar styrene.

47. r12 and r21 are equivalent to r1 and r2 in Q-e scheme
The monomer reactivity ratio for monomer 2
The monomer reactivity ratio for monomer 1
r12 and r21 are equivalent to r1 and r2 in Q-e scheme
The values of  and  for a monomer are obtained from monomer reactivity
ratios for copolymerization of that monomer with a series of reference monomers.

48. A plot of the data according to

49. Monomer sequence distributions in the terminal model
Alternation tendency
Monomer sequence distributions in the terminal model

50. 6-3c Terminal Model for Rate of Radical Copolymerization
Diffusion-controlled termination model
Average termination rate constant
F1 and F2 : the copolymer composition
Rate of copolymerization; different from the composition, Ri anf kt should be included
Because the average propagation rate
constant is dependent on the comonomer feed composition, monomer reactivity ratios, and homopropagation rate constants derived by Fukuda and coworkers

51. 6-4 Ionic Copolymerization
⇒ very limited # of monomers are possible compared with
radical copolymerization
* General rule
① r1 · r2 ~ 1
② Similar reactivity of ionic species toward two radicals
∴ no alternation (see why alternation is possible
in radical copolymerization)
Sensitivity of the r1 · r2 changed according to rxn condition
change ⇒ in radical not much sensitive !

52. 6-4a Cationic Copolymerization
6-4a-1 Reactivity
① Polar effect
reactivity of styrene
Normally obtained using 1/r1
Hammett sigma-rho relationship
log(1/r1)
⇒ polar effect ρ
-0.27
P-OCH3 σ
+0.71
m-NO2

53. 6-4a-1 Reactivity ② Steric effect
⇒ Still 1,2-disubstituted alkenes have some r value
ex) in cationic polymerization
cf) in radical, 1,2-disubstituted monomers (diethyl maleate,
furmaronitrile, maleic anhydride) ; r1 ~ 0
* There is a tendency for 1,2-disubstituted alkenes to self-propagate
in cationic polymerization ∵ C+ is more reactive than C ·

54. 6-4a-2 Effect of Solvent and Counterion
① Effect of solvent and initiator
Different counter
Ion effect
; In hexane, copolymer is microheterogeneous
⇒ polar p-chlorostyrene is located preferentially around
the copolymer propagating chain
; In nitrobenzene, copolymer is well dissolved
⇒ originally more reactive isobutylene in more incorporated
into the copolymer

55. SbCl5 ~ strongest initiator (strongest acid); free ion + ion pair,
l2 ~ weakest initiator ; normally covalent species
⑴ Generally not very sensitive to solvent polarity & counterion except SbCl5 case
⑵ Initiator strength ↑ ⇒ styrene content↑ for low polarity solvent (toluene & 1,2-dichloroethane), St is more around the propagaing species
∵ p-methylstyrene more polar & more reactive than styrene
∴ generally p-methylstyrene preferentially solvates the propagating ions and is preferentially incorporated into the copolymer ⇒ p-methylstyrene content ~ above 50%
⑶ Good solvent (nitrobenzene) ; original reactivity
⇒ counter ion is less important ∵ solvent covers the active site
SbCl5 : solvent polarity ↑, complexing ability of monomer with propagating chain 
then reactivity is determined by the original monomer reactivity

56. 6-4a-3 Effect of Temperature
T ↑ ⇒ r = 1
∵ r with smaller value increase faster with the increase of
temperature
No general trend !
⇒ different amount of propagating species with different identities (free ion, ion pairs, covalent species)

57. 6-4 Ionic Copolymerization
6-4b Anionic Copolymerization
6-4b-1 Reactivity
~ The opposite of those in cationic copolymerization
6-4b-2 Effects of Solvent and Counterion

58. ① Lithium ion (tightly bound), large effect due to solvent
; poor solvent ~ less reactive, isoprene is rich
∵ isoprene is preferentially complexed with lithium
good solvent ~ inherent reactivity
more reactive styrene is rich in later copolymer
② Sodium ; larger, loosely bound ~ less effect due to solvent

59. 6-4b-3 Effect of Temperature
~ Not much reported
Styrene – butadiene with s-butyllithium in hexane (poor solvent) r1 r2
0oC
0.03
13.3
50oC
0.04
11.8
; not much change
Styrene – butadiene with s-butyllithium in THF (good solvent) r1 r2
0oC
11.0
0.04
50oC
4.00
0.30
; lithium ion solvated with butadiene
∵ butadiene is preferentially complexed with lithium

60. 6-5 Deviation from Terminal Copolymerization Model
6-5a Kinetic Penultimate Behavior

61. 6-5 Deviation from Terminal Copolymerization Model
6-5a Kinetic Penultimate Behavior
the reactivity of the propagating species is affected by the next-to-last (penultimate) monomer unit: second-order Markov or penultimate behavior

62. The monomer and radical reactivity ratios
The M1 centered triad monomer sequence distributions
If there is no penultimate effect

63. terminal model
styrene (M1) and diethyl fumarate (M2). The solid line represents the terminal model
with r1 = 0.22, r2 =
The dotted line represents the
terminal model
The solid line represents the
implicit penultimate model
The copolymer composition data follow the terminal model well.
The propagation rate constant shows a penultimate effect,

64. 6-6 Copolymerization Involving Dienes
6-6a Crosslinking
Diene monomer : two double bond
~ used in copolymerization to produce a cross-linked structure
~ low concentration in copolymerization is enough to get X-liked polymers
ex) MMA - ethylene glycol dimetharylate (EGDM)
vinyl acetate – divinyl adipate (DVA)
styrene – divinyl benzene
Case Ⅰ : r1 = r2 , F1 = f1, A + BB
at P (extent of rxn)
P[A] : reacted A double bond
P[B] : reacted B double bond
P2[BB] : reacted BB monomer
∴ [B] =2[BB]
The # of crosslinks : P2[BB] ~ (the # of BB monomers in which
both B double bond are reacted)
The # of polymer chain : ([A] + [B])P/Xw ~ (the total # of A & B double
bonds reacted / the degree of polymerization)

65. The critical extent of rxn at Pc (gel point)
~ The # of crosslinks per chain is ½
⇒ more than this, crosslinks ⇒ then gelation !
∴ P2[BB] / {([A] + [B])P/Xw} = 1/2
~ the equation confirm the
experimental data at low conc.
of diene
at high conc. : calculated < observed
∵ ① cyclization of dienes
② lower reactivity of second double
bond

66. The branching coefficient α; defined as the probability that a given functional group of a branch unit at the end of a polymer chain segment leads to
another branch unit.
The multifunctional monomer Af ; branch unit
The segments between branch units ; chain segments.
If f = f = 4
The criterion for gelation in a system containing a reactant of functionality f is that at least one of the (f-1) chain segments radiating from a branch unit will in turn be connected to another branch unit.
The probability for this occurring is simply 1/(f-1) and the critical branching coefficient αc for gel formation is

67. When α(f-1) = 1, a chain segment will, on the average, be succeeded by α(f-1) chains. Of these α(f-1) chains a portion a will each end in a branch point so that α2(f-1)2 more chains are created.
The branching process continues with the number of succeeding chains becoming progressively greater through each succeeding branching reaction. The growth of the polymer is limited only by the boundaries of the reaction vessel.
If, on the other hand, α(f-1) is less than 1, chain segments will not be likely to end in branch units.
For a trifunctional reactant (f=3) the critical value (αc) of a is simply 1/2.

68. Case Ⅱ : A & BB, but r1 ≠ r2 ~ reasonable
if [A] >> [BB]
If r2 > r1 : diene is more reactive than A
then X-links occur at early stage of rxn
If r2 < r1 : X-links delayed

69. Case Ⅲ : monomer A + monomer BC
A & B have equal reactivity, C has very low reactivity
ex) MMA + allylmethacrylate
~ very small values due to low reactivity of allyl groups
X-linking occurs at the very late stage of the polymerization
We need to select one of them !

70. 6-6b Alternating Intra/Intermolecular Polymerization;
Cyclopolymerization
At higher concentration of diene Pc,obs is larger than Pc,cal due to the cyclization

71. 6-6b Alternating Intra/Intermolecular Polymerization;
Cyclopolymerization
⇒ diallyl quaternary ammonium salts
~ soluble in water (no X-linking)
; no or little residual double bonds
→ alternating intra/intermolecular polymerization
No report on 4-membered rings,
while 5-membered rings are formed from 1,5-denes
* Several report on 7-membered rings, ex

72. * Competetion between cyclization (Rc) and Propagation (Rp)
fraction of cyclized units
kc/kp can be obtained ~ slope of
* Most symmetrical 1,6-diene ⇒ 6-membered ring
kc/kp = 2-20 moles/L ⇒ high tendency for the cyclization
Temp ↑ ⇒ cyclization ↑
∵ Activation E of cyclization > activation E of propagation
* Unsymmetrical 1,6-diene
ex) allyl methacrylate ⇒ lower kc/kp
* Cyclization for the formation of 7-membered or more
very low small kc/kp

73. * Bicyclic structure formation via cyclopolymerization
(or cyclization)

74. 6-6c Interpenetrating Polymer Networks
⇒ Polymerization with cross-linking in the presence of
another already cross-linked polymer
ex) X-linked PU is swollen
Add MMA, trimethylolpropane trimethacrylate, benzoyl peroxide
⇒ heating ⇒ combining properties of two different X-linked polymers

75. 6-7 Other Copolymerization
Vinyl monomers + sulfur dioxide, SO2
carbon monoxide, CO
oxygen, O2
no homopolymerization of SO2, CO, O2, while
⇒ Copolymerizations with alkenes are possible
⇒ ethylene + CO ⇒ alternating copolymer : polyketone
The reaction with sulfur dioxide
Ethylene, α-olefin, vinyl chloride, vinyl acetate
: without strong EWG
: 1:1 alternating copolymer
Styrene, butadiene
: SO2 unit is less than 50% in the copolymer
: strong tendency for the ability of homopolymerization
AN, MMA
: with strong EWG
: no copolymerization

76. 6-8 Applications of Copolymerization
6-8a Styene
~ major styrene polymers are copolymer not homopolymer ; brittle
i) SBR : styrene – butadiene copolymer
25% styrene + 75% butadiene ⇒ produced by emulsion polymerization
~ similar to natural rubber (ex. Tensile strength)
~ better ozone resistance & weatherability than natural rubber
~ poorer resilience (탄성력) and greater heat buildup than natural rubber
~ tire, hose, coated fabric, electrical insulator, belting
50~70% Styrene + 30~50% butadiene
~ latex paint
~ small amount of unsaturated carboxylic acid;
backing material for carpet
About 2 billion pounds per year are produced in the United States.

77. SBR은 Styrene과 Butadiene을 저온 유화 중합법으로 제조한 제품입니다
SBR은 Styrene과 Butadiene을 저온 유화 중합법으로 제조한 제품입니다. SBR은 천연고무에 비해 품질이 균일하고 특히 내열성과 내마모성이 우수하며, 타이어, 신발, 산업용품 등의 재료로 널리 사용되고 있습니다.

78. packaging (bottle closures and sprayers),
ii) SAN : styrene – AN
⇒ 10~40% AN content
AN : intermolecular force, solvent resistence, permeability,
improved tensile strength, raise upper use temperature
~ similar impact resistance
Applications: houseware (refrigerator shelves and drawers, coffee mugs),
packaging (bottle closures and sprayers),
furniture (chair backs and shells),
electronics (battery cases, cassette parts).
About 200 million pounds per year are produced in US.

79. iii) ABS : Acrylonitrile–butadiene–styrene polymers
- combine the properties of SAN with greatly improved resistance to impact.
produced by emulsion, suspension, or bulk copolymerization of styrene–acrylonitrile in the
presence of a rubber.
About 2 billion pounds per year of ABS are produced in the United States.
Applications
housewares (refrigerator doors, sewing machine and hair-dryer housings, luggage,
furniture frames, margarine tubs)
housing and construction (pipe, conduit, fittings, bathtubs and shower stalls),
transportation (automotive instrument panels, light housings, grilles)
business machine housings (telephone, calculator),
recreation (golf clubs, boat hulls, camper top or shell, snowmobile shroud).

80. iv) HIPS (high-impact polystyrene) and GPPS : general purpose polystyrene
~ rubber (normally(*1,3-butdiene))+ styrene ; polymerization in the presence of rubber
~ cheaper than ABS, similar application

81. They can be used in physical blends with other polymers, such as polycarbonates, polyesters, and polyamides, to improve impact resistance!

82. 6-8b Ethylene more than 1 billion pounds in the United States
~ LDPE (radical), HDPE (coordination)
i) EVA : ethylene - vinyl acetate copolymer
more than 1 billion pounds in the United States
~ VA ↑ ⇒ crystallinity ↓, Tm ↓, chemical resistance ↓
optical clarity ↑, impact and stress crack resistence ↑
flexibility ↑, adhesion ↑
~ 2-18% VA : clean rap, frozen food package, coating on aluminum foil
~ 20-30% VA : blends with parafin wax
carpet backing, hot-melt adhesive

83. iv) EVOH : Hydrolysis of EVA copolymers yields ethylene–vinyl alcohol copolymers
~ excellent barrier polymer
~ food container
The poor moisture resistance of EVOH is overcome by coating, coextrusion, and lamination with other substrates.

84. barrier polymers
AN/styrene copolymer
Oxyalkylene Polymers with Alkylsulfonylmethyl Side Chains: Gas Barrier Properties, Journal of Polymer Science: Part B: Polymer Physics 36 (1998) 75-83

86. M. Salame & S. Steingiser (1977) Barrier Polymers, Polymer-Plastics
Technology and Engineering, 8:2,

97. 6-8c Unsaturated Polyester
LMW unsaturated polyester + inintiator + monomer
→ curing atificial marble
The fumarate–styrene system : more of an alternating copolymerization behavior than the fumarate–methyl methacrylate system.
Methyl methacrylate tends to form a small number of long crosslinks (large value of n), while styrene forms a larger number of short crosslinks (small value of n).
Thus the styrene copolymers are harder and tougher than methyl methacrylate copolymers

98. 6-8e Others
Nafion; tetrafluoroethylene + X (p 533)
Used for fuel cell, battery, and electrochemical membranes as well as
acid catalysts.

99. Nitrile rubber (NBR): a copolymer of 1,3-butadiene with 20–40% acrylonitrile,
- oil resistance.
More than 150 million pounds are produced annually in the United States.
Applications: fuel tanks, gasoline hoses, and creamery equipment.

100. Nitrile resin :copolymerizing acrylonitrile with about 20–30% styrene or methyl methacrylate in the presence of NBR or SBR rubber
-a blend of the graft terpolymer and homo-copolymer.
Applications: extruded and blow-molded containers for household, automotive, and non beverage foods (spices, vitamins, candy).