Page 23 - Biodegradable Polyesters

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Biodegradable Polyesters: Synthesis, Properties, Applications
Chi Zhang

1.1
Historical Overview on the Origin of Polymer Science and Synthesis of Polyamides
and Polyesters
There are some persons who stand out prominently in any review of the history
of polyesters. As early as in 1911, Meyer [1] found that the saponification of
polyesters of polyacids and polyalcohols and the hydrolysis of a glycerol ester
proceeds in acid and alkaline solution, and, the hydrolysis can only be detected
under certain conditions with heterogeneous saponification. However, he did
not mention the molecular weights of the polyesters used. Hermann Staudinger
(1881–1965) is recognized as the father of polymer chemistry because of his
great contributions to polymer science (Figure 1.1).
In 1920, Staudinger reported [3] that polymerization processes in the wider
sense are all processes in which two or more molecules combined to a result
in a product of the same composition but with higher molecular weight. These
high-molecular-weight compounds are produced by two basic polymerization
processes: the first was called condensation polymerization(nowadays, termed
step-growth polymerization) in which polymers are formed by stepwise reactions
between functional groups of monomers, usually containing heteroatoms such
as nitrogen or oxygen; and the second called chain-growth polymerization (or
addition polymerization), which involves double or triple carbon–carbon bonds
breaking and the linking together of the other molecules. In reactions, these
unsaturated monomers are able to form repeating units where the main-chain
backbone usually contains only carbon atoms. In his paper entitled “Polymeriza-
tion” [3], Staudinger presented several reactions that form high-molecular-weight
molecules by linking together a large number of small molecules. This new con-
cept was the base for “macromolecular chemistry” in the history of science.
Staudinger noticed that the natural fibers were not comprised of small molecules
as imagined earlier [4] and he gave an early formal awareness of “small” differing
from “big” molecules. Thanks to his pioneering concept, in the past 90 years, the
molecular architectures of synthetic polymers and biopolymers have become
clearly known and most synthetic polymers can be designed, characterized, and

Biodegradable Polyesters, First Edition. Edited by Stoyko Fakirov.
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2015 by Wiley-VCH Verlag GmbH & Co. KGaA.