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(M0 = 56.0)
8. nCF2=CF2 (M0 = 100)
(M0 = 44.0)
(M0 = 113)
poly (vinyl chloride), "vinyl"
poly aery lonitrile, "acrylic"
0=C-0-CH3 poly (methyl methacrylate), Plexiglas, lucite CH3
poly (ethylene oxide), carbowax
-t(CH2)s-C-Nin poly(e-caprolactam), nylon-6
aMolecular weights of repeat units and common names of the products are
included for future reference. Reactions 9 and 10 are ring-opening
polymerizations and are discussed in Sec. 5.10.
The Chains and Averages of Polymers
molecules can be manipulated. When such reactants enter as impurities,
the undesired results can be disasterous! Marvelt has remarked that more
money has been wasted in polymer research by the use of impure monomers
than in any other manner.
Table 1.2 lists several examples of condensation reactions and
products. Since the reacting monomers can contain different numbers of
carbon atoms between functional groups, there are quite a lot of
variations possible among these basic reaction types.
The inclusion of poly (dimethyl siloxane) in Table 1.2 serves as a
reminder that polymers need not be organic compounds. The physical
properties of inorganic polymers follow from the chain structure of these
molecules, and the concepts developed in this volume apply to them and to
organic polymers equally well. For example, poly (dimethyl siloxane)
shows a very low viscosity compared to other polymers of comparable
degree of polymerization. We shall see in Chap. 2 that this is traceable
to its high chain flexibility, which, in turn, is due to the high
concentration of chain backbone atoms with no substituents. We shall not
examine the classes and preparations of the various types of inorganic
polymers in this text. References in inorganic chemistry should be
consulted for this information.
We conclude this section with a short discussion of naturally
occurring polymers. Since these are of biological origin, they are also
called biopolymers. Although our attention in this volume is primarily
directed toward synthetic polymers, it should be recognized that
biopolymers, like inorganic polymers, have physical properties which
follow directly from the chain structure of their molecules. The
synthesis by and contribution to living organisms by these biopolymers is
the subject matter of other disciplines, such as biochemistry and
molecular biology. The reader who desires information on this aspect of
these naturally occurring polymers should consult references in these
As examples of natural polymers, we consider polysaccharides,
proteins, and nucleic acids. Another important natural polymer,
polyisoprene, will be considered in Sec. 1.6.
Polysaccharides are macromolecules which make up a large part of the
bulk of the vegetable kingdom. Cellulose and starch are, respectively,
the first and second most abundant organic compounds in plants. The
former is present in leaves and grasses; the latter in fruits, stems, and
roots. Because of their abundance in nature and because of contemporary
interest in renewable resources, there is a great deal of interest in
these compounds. Both cellulose and starch are hydrolyzed by acids to D-
glucose, the repeat unit in both polymer chains.
t Carl S. Marvel, another pioneer in polymer chemistry, reminisces about
the early days of polymer chemistry in the United States in the Journal
of Chemical Education, 58:535 (1981).
Table 1.2 Reactions by Which Several Important Condenstation Polymers are
n HOfCH^OH + n hoocc6h4cooh -
WCH^-O-Ñ^^ÑÓ 2n H20 M0 = 192
poly (ethylene terephthalate), Terylene, Dacron, Mylar
nHOCH(CH2)J0COOH - fOCH(CH2)10C+n + nH2o
Mo = 282
poly(l 2-hydroxystearic acid)
n H2N(CH2)6NH2 + n C1C0(CH2)4C0C1 - fNH-(CH2)ft N C-(CH2)4-COln 4-
2nHCl M0 = 226
poly(hexamethylene adipamide), nylon 6,6
nHO(CH2)4OH+ n 0=C=N(CH2)6N=C=0 -
M0 - 258
poly (tetramethylene hexamethylene urethane), spandex,
n C1COC1 + n HO-c-OH -