Monomer type | Radical | Cationic | Anionic | Coordination |
---|---|---|---|---|
Ethylene | + | – | – | + |
1-Alkyl olefins (α-olefins) | – | – | – | + |
1,1-Dialkyl olefins | – | + | – | + |
1,3-Dienes | + | + | + | + |
Styrene, α-methyl styrene | + | + | + | + |
Halogenated olefins | + | – | – | – |
Vinyl ethers | – | + | – | – |
Vinyl esters | + | – | – | – |
Acrylic and methacrylic esters | + | – | + | – |
Acrylonitrile and methacrylonitrile | + | – | + | – |
N-Vinyl carbazole | + | + | – | – |
N-Vinyl pyrrolidone | + | + | – | – |
Aldehydes, ketones | – | + | + | – |
8.1 Characteristics of Ionic Chain Polymerization
Polymer or copolymer
| Major uses |
---|---|
Cationic
a
| |
Polyisobutylene and polybutenesb (low and high molecular weight) | Adhesives, sealants, insulating oils, lubricating oil and grease additives, moisture barriers |
Isobutylene-isoprene copolymerc (“butyl rubber”) | Inner tubes, engine mounts and springs, chemical tank linings, protective clothing, hoses, gaskets, electrical insulation |
Isobutylene-cyclopentadiene copolymer
| Ozone-resistant rubber |
Hydrocarbond and polyterpene resins | Inks, varnishes, paints, adhesives, sealants |
Coumarone-indene resinse and poly (vinyl ether)s | Flooring, coatings, adhesives, polymer modifiers, tackifiers, adhesives |
Anionic
f
| |
cis-1,4-Polybutadiene | Tires |
cis-1,4-Polyisoprene | Tires, footwear, adhesives, coated fabrics |
Styrene-butadiene rubber(SBR)g
| Tire treads, belting, hoses, shoe soles, flooring, coated fabrics |
Styrene-butadiene block and star copolymers | Flooring, shoe soles, artificial leather, wire, and cable insulation |
ABA block copolymers (A = styrene, B = butadiene or isoprene) | Thermoplastic elastomers |
Polycyanoacrylateh
| Adhesives |
8.2 Cationic Polymerization
8.2.1 Initiators of Cationic Polymerization
8.2.2 Reaction Mechanisms of Cationic Polymerization
Solvent | k
p
(L/mol-s) |
---|---|
CH2Cl2
| 17 |
CH2Cl2/CCl4, 3/1 | 1.8 |
CH2Cl2/CCl4, 1/1 | 0.31 |
CCl4
| 0.12 |
Solvent |
k
p
+
|
k
p
c
|
k
p
±
|
---|---|---|---|
Polar | Decrease | Decrease for high dipole moment transition state | Increase for high dipole moment transition state |
Nonpolar | Increase | Increase | Decrease |
Solvent | ε |
k
p
+
(L/mol-s) |
---|---|---|
Benzene | 2.7 | 57 |
None | 3.0 | 130 |
(C2H5)2O | 3.7 | 34 |
CH2Cl2
| 6.0 | 1.5 |
CH3NO2
| 19.5 | 0.02 |
8.2.3 Kinetics of Cationic Polymerization
Parameter | Styrene |
i-Butyl vinyl ether |
p-Methoxy styrene |
N-Vinyl carbazole |
---|---|---|---|---|
[Styrene], M | 0.27–0.40 | – | – | |
[CF3SO3H], M | 3.8–7.1 × 10−3
| – | – | |
[ϕ
3C+SbCl6], M | – | 6.0 × 10−5
| – | |
k
i
, L/mol-s | 10–23 | 5.4 | ||
k
d
, mol/L | 4.2 × 10−7
| – | ||
k
p
+
, L/mol-s | 1.2 × 106
| 7.0 × 103
| 3.6 × 105
| 6.0 × 105
|
k
p
±
, L/mol-s | 1.0 × 105
| – | 4.1 × 104
| 5.0 × 104
|
k
ts
+ k
t
, s−1
| 170–280 | 0.2 | – | – |
k
tr
, M, L/mol-s | 1–4 × 103
| 1.9 × 102
| – | – |
Rate constant | Cationic | Free radical |
---|---|---|
k
t
| Low | High |
k
p
| High | Low |
R
p
|
k
p
/k
t
high | (k
p
/k
t
)1/2 low |
8.2.4 Commercial Cationic Polymerization
8.3 Anionic Polymerization
8.3.1 Reaction Mechanisms of Anionic Polymerization
8.3.2 Kinetics of Anionic Polymerization with Termination
Solvent | Dielectric constant |
k
p
app
L/mol-s |
---|---|---|
Benzene | 2.2 | 2 |
Dioxane | 2.2 | 5 |
Tetrahydrofuran | 7.6 | 550 |
1,2-Dimethoxy ethane | 5.5 | 3,800 |
Polymerization in tetrahydrofuran | ||||
---|---|---|---|---|
Counterion |
\( k_{p}^{ \mp } \)
|
K × 107
|
\( k_{p}^{ - } \)
|
\( k_{p}^{ \mp } \) for dioxane |
Li+
| 160 | 2.2 | 6.5 × 104
| 0.94 |
Na+
| 80 | 1.5 | 6.5 × 104
| 3.4 |
K+
| 60–80 | 0.8 | 6.5 × 104
| 19.8 |
Rb+
| 50–80 | 0.1 | 6.5 × 104
| 21.5 |
Cs+
| 22 | 0.02 | 6.5 × 104
| 24.5 |
Cation | Styrene | Methyl methacrylate |
---|---|---|
Li+
| 160 | 1 |
Na+
| 80 | ~30–33 |
K+
| 60–80 | ~30–33 |
Rb+
| 50–80 | ~30–33 |
Cs+
| 22 | ~30–33 |
Factor | Anionic | Cationic |
---|---|---|
Propagating species | Anionic ion pair/free ions | Cationic ion pair/free ions |
Difference in ion pair/free ion reactivity | Large | Small |
Temperature sensitivity | Relative small | Large |
E
R
= E
i
+ E
p
− E
t
| Positive | Negative (mostly E
t
> E
i
+ E
p
) |
Solvent | Aliphatic/aromatic hydrocarbon and ether | Prefer polar solvent |
Halogenated solvent | No (facile nucleophilic substitution Rx) | Yes |
Living polymerization
| Most | Seldom |
8.4 Group Transfer Polymerization
Monomersa
| Initiatorsa
| Catalystsa
| Solvents |
---|---|---|---|
Anionicb
HF2
−
CN−
| Acetonitrile 1,2-Dichloroethaned
Dichloromethaned
| ||
Me3SiCH2CO2Me | N3
−
Me3SiF2
| N,N-Dimethylacetamide N,N-Dimethylacetamide | |
Me3SiCN | Lewis acidc
| Ethyl acetate | |
RSSiMe3
| ZnX2
R2AlCl | Propylene carbonate Tetrahydrofuran | |
ArSSiMe3
| (R2Al)2O | Toluened
| |
8.5 Chain Polymerization of Carbonyl Monomer
Monomer | Tc (°C) |
---|---|
Formaldehyde | 119 |
Trifluoroacetaldehyde | 81 |
Propanol | −31 |
Acetaldehyde | −39 |
Pentanal | −42 |