Prepared for publication by A. D. Jenkins (UK), P. Kratochvìl
(Czech Republic), R. F. T. Stepto (UK), and U. W. Suter (Switzerland)
REACTIONS
3.1 polymerization
The process of converting a monomer (see
Definition 2.1) or a mixture of monomers into a polymer
(see Definition 2.2).
3.2 oligomerization
The process of converting a monomer (see
Definition 2.1) or a mixture of monomers into an oligomer (see
Definition 2.3).
Note
An oligomerization by chain reaction carried
out in the presence of a large amount of chain-transfer
(see Definition 3.24) agent, so that the end-groups
(see Definition 1.35) are essentially fragments of the chain-transfer
agent, is termed telomerization.
3.3 homopolymerization
Polymerization (see Definition 3.1)
in which a homopolymer (see Definition
2.4) is formed.
3.4 copolymerization
Polymerization (see Definition 3.1)
in which a copolymer (see Definition
2.5) is formed.
3.5 co-oligomerization
Oligomerization (see Definition 3.2)
in which a co-oligomer (see Definition
2.7) is formed.
3.6 chain polymerization
A chain reaction in which the growth of a polymer (see
Definition 1.1) chain (see Definition
1.30) proceeds exclusively by reaction(s) between monomer(s) (see
Definition 2.1) and reactive site(s) on the polymer chain with
regeneration of the reactive site(s) at the end of each growth step.
Notes
1. A chain polymerization consists of initiation and propagation
reactions, and may also include termination and chain transfer (see
Definition 3.24) reactions.
2. The adjective chain in chain polymerization
denotes a chain reaction rather than a polymer chain.
3. Propagation in chain polymerization usually occurs without
the formation of small molecules. However, cases exist where a low-molar-mass
by-product is formed, as in the polymerization of oxazolidine-2,5-diones
derived from amino acids (commonly termed amino-acid N-carboxy
anhydrides). When a low-molar-mass by-product is formed, the adjective
condensative is recommended to give the term condensative
chain polymerization.
4. The growth steps are expressed by
Px + M Æ
Px+1 (+ L) {x}
{1, 2, º }
where Px denotes the growing chain of
degree of polymerization x, M a monomer, and L a low-molar-
mass by-product formed in the case of condensative chain polymerization.
5. The term chain polymerization may be qualified further,
if necessary, to specify the type of chemical reactions involved in
the growth step, e.g., ring-opening chain polymerization, cationic
chain polymerization.
6. There exist, exceptionally, some polymerizations that proceed
via chain reactions that, according to the definition, are
not chain polymerizations. For example, the polymerization
HSXSH + H2C=CHYCH=CH2
Æ SXSCH2CH2YCH2CH2
proceeds via a radical chain reaction with
intermolecular transfer of the radical center. The growth step, however,
involves reactions between molecules of all degrees of polymerization
and, hence, the polymerization is classified as a polyaddition (see
Definition 3.8). If required, the classification can be made more
precise and the polymerization described as a chain-reaction polyaddition.
3.7 polycondensation
A polymerization (see Definition 3.1)
in which the growth of polymer (see Definition
1.1) chains (see Definition 1.30)
proceeds by condensation reactions between molecules of all degrees
of polymerization (see Definition 1.13).
Notes
1. The growth steps are expressed
by
Px + Py Æ
Px+y + L {x}
{1, 2, º };
{y} {1, 2, º
}
where Px and Py
denote chains of degree of polymerization x and y, respectively,
and L a low-molar- mass by-product.
2. The earlier term polycondensation was synonymous
with condensation polymerization. It should be noted that the
current definitions of polycondensation and condensative chain polymerization
were both embraced by the earlier term polycondensation.
3.8 polyaddition
A polymerization (see Definition 3.1)
in which the growth of polymer (see Definition
1.1) chains (see Definition 1.30)
proceeds by addition reactions between molecules of all degrees of
polymerization (see Definition 1.13).
Notes
1. The growth steps are expressed
by
Px + Py Æ
Px+y {x}
{1, 2, º };
{y} {1, 2, º
}
where Px and Py
denote chains of degrees of polymerization x and y,
respectively.
2. The earlier term addition polymerization embraced
both the current concepts of polyaddition and chain polymerization,
but did not include condensative chain polymerization.
3.9 statistical copolymerization
A copolymerization (see Definition 3.4)
in which a statistical copolymer (see
Definition 2.9) is formed.
3.10 random copolymerization
A copolymerization (see Definition 3.4)
in which a random copolymer (see Definition
2.10) is formed.
3.11 alternating copolymerization
A copolymerization (see Definition 3.4)
in which an alternating copolymer (see
Definition 2.11) is formed.
3.12 periodic copolymerization
A copolymerization (see Definition 3.4)
in which a periodic copolymer (see
Definition 2.12) is formed.
3.13 ring-opening polymerization
A polymerization (see Definition 3.1)
in which a cyclic monomer (see Definition
2.1) yields a monomeric unit (see
Definition 1.8) which is acyclic or contains fewer cycles than
the monomer.
Note
If the monomer is polycyclic, the opening
of a single ring is sufficient to classify the reaction as a ring-opening
polymerization.
3.14 ring-opening copolymerization
A copolymerization (see Definition 3.4)
which is a ring-opening polymerization (see
Definition 3.13) with respect to at least one monomer (see
Definition 2.1).
3.15 radical polymerization
A chain polymerization (see Definition
3.6) in which the kinetic-chain carriers are radicals.
Note
Usually, the growing chain end bears an
unpaired electron.
3.16 radical copolymerization
A copolymerization (see Definition 3.4)
which is a radical polymerization (see
Definition 3.15).
3.17 ionic polymerization
A chain polymerization (see Definition
3.6) in which the kinetic-chain carriers are ions or ion-pairs.
Note
Usually, the growing chain ends are ions.
3.18 ionic copolymerization
A copolymerization (see Definition 3.4)
which is an ionic polymerization (see
Definition 3.17).
3.19 anionic polymerization
An ionic polymerization (see Definition
3.18) in which the kinetic-chain carriers are anions.
3.20 cationic polymerization
An ionic polymerization (see Definition
3.18) in which the kinetic-chain carriers are cations.
3.21 living polymerization
A chain polymerization from which chain transfer and chain termination
are absent.
Note
In many cases, the rate of chain initiation
is fast compared with the rate of chain propagation, so that the number
of kinetic-chain carriers is essentially constant throughout the polymerization.
3.22 living copolymerization
A copolymerization (see Definition 3.4)
which is a living polymerization (see
Definition 3.21).
3.23 cyclopolymerization
A polymerization (see Definition 3.1)
in which the number of cyclic structures in the constitutional units
(see Definition 1.14) of the resulting
macromolecules (see Definition 1.1)
is larger than in the monomer molecules (see
Definition 1.3).
3.24 chain scission
A chemical reaction resulting in the breaking of skeletal bonds (see
Definition 1.50).
3.25 depolymerization
The process of converting a polymer (see
Definition 2.2) into a monomer (see
Definition 2.1) or a mixture of monomers.
Note
Unzipping is depolymerization occurring
by a sequence of reactions, progressing along a macromolecule (see
Definition 1.1) and yielding products, usually monomer molecules
(see Definition 1.3), at each reaction
step, from which macromolecules similar to the original can be regenerated.