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The role of ring‐ring equilibria in thermodynamically controlled polycondensations
Author(s) -
Kricheldorf Hans R.
Publication year - 2003
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200350902
Subject(s) - ring (chemistry) , chain (unit) , chemistry , polymer , ring size , component (thermodynamics) , molar ratio , polymer chemistry , catalysis , thermodynamics , organic chemistry , physics , astronomy
Thermodynamically controlled polycondensations (TCPs) involve rapid equilibration reactions, such as transesterification, transamidation, etc. An important component of these equilibration reactions is the reversible formation of cyclic oligomers and polymers by “back‐biting”. Therefore, TCPs were described in the previous literature in terms of ring‐chain equilibria. The present study presents a complementary theory saying that ring‐chain equilibria automatically include ring‐ring equilibria which gain in importance with higher conversions because the molar ratio of rings versus linear chains rapidly increases. At 100% conversion, all reaction products will be cycles and the ring‐ring equilibria limit the chain growth. Several polycondensations cited from the literature are discussed in the light of the new theory.