Predicting and Measuring the Sequence Distribution of Condensation Polymers - Mathematical Approaches to Polymer Sequence Analysis and Related Problems - page 233

Fig. 11.4 The synthesis of a copoly(ester-amide) starting from two cyclic monomers

The latter formulas are not easy to derive. Figure 11.4 reports a copolymerization
reaction involving the lactic acid cyclic dimer and another cyclic dimer.

11.6 Bacterial Synthesis of Condensation Copolymers

Bacteria such as Pseudomonas olevarans , Pseudomonas putida , Alcaligenes euthro-
phus , Rodospirillum rubrum ,and Ralstonia eutropha are able to produce polymers
and copolymers, mainly polyesters and copolyesters [ 17 ]. Bacterial synthesis is the
result of many chemical reactions. No wonder, therefore, if the sequence of the re-
sulting copolymer is unknown in the sense that nobody has ever proposed a theory
that predicts the cited sequence.
It is reasonable to assume that the copolymer is a mixture of copolymers. As
discussed in detail previously, mixtures of two copolymers display sequences due
to both components of the mixture. The molar fraction,

I.A m B n / , of the oligomer

A m B n is given by:

.m C n/Š
mŠ nŠ .E mix .e A / m .1 e A / n
C .1 E mix /.d A / m .1 d A / n /;

IŒA m B n D

(11.11)

e A and

where d A are the compositions (the molar fraction of A units) of the first

and the second copolymer, and E mix is the molar fraction of the first copoly-

mer in the mixture. From the above compact formula, the explicit expressions
for each oligomer can be derived. The most useful ones are those from dimers to
hexamers [ 18 ].

11.7 Condensation Copolymerization by Melt-Mixing

The topic of exchange reactions in condensation polymers is vast and reviews
covering the entire topic or part of it have been published [ 19 - 22 ]. Binary poly-
mer melts are obtained by heating binary polymer mixtures above the melting