Page 266 - Carrahers_Polymer_Chemistry,_Eighth_Edition

Copolymerization 229

TABLE 7.2
Typical Q and e Values for Monomers
Monomer Q e
Benzyl methacrylate 3.64 0.36
Methacrylic acid 2.34 0.65
2-Fluoro-1,3-butadiene 2.08 –0.43
P-Cyanostyrene 1.86 –0.21
P-Nitrostyrene 1.63 0.39
2,5-Dichlorostyrene 1.60 0.09
Methacrylamide 1.46 2.24
p-Methoxystyrene 1.36 –1.11
2-Vinylpyridine 1.30 –0.50
p-Methylstyrene 1.27 –0.98
Methacrylonitrile 1.12 0.81
p-Bromostyrene 1.04 –0.32
Styrene 1.00 –0.80
m-Methylstyrene 0.91 –0.72
Methyl methacrylate 0.74 0.40
Acrylonitrile 0.60 1.20
Methyl acrylate 0.42 0.60
Vinylidene chloride 0.23 0.36
Vinyl chloride 0.044 0.20
Vinyl acetate 0.026 –0.22

k  Q  − ee e )
( −
r = 11 =  1  e 11 2
1
k 12  Q 2  (7.25b)
Similarly,

k = P Q e −(e ) 2 (7.26)
2
2
22
2
−e e
k = P Q e 1 2 (7.27)
1
2
21
and,
k  Q  − ee e )
( −
r = 22 =  2  e 2 2 1
1
k 21  Q 1  (7.28)
Therefore,
1 2 or r r = exp[–(e – e ) ]
r r = e −(e −e ) 2 1 2 1 2 2 (7.29)
1 2
It is important that while the reactivity is related to resonance stability of the macroradical M , the
1
•
composition of the copolymer is related to the relative polarity of the two monomers M and M • 2
1
7.3 COMMERCIAL COPOLYMERS
One of the first commercial copolymers, introduced in 1928, was made of VC (87%) and VAc (13%)

(Vinylite). Because the presence of the VAc mers disrupted the regular structure of PVC, the copol-
ymer was more flexible and more soluble than PVC itself.

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