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Kinetics and mechanism of cyclic esters polymerization initiated with covalent metal carboxylates, 5 . End‐group studies in the model ε ‐caprolactone and L , L ‐dilactide/Tin(II) and zinc octoate/butyl alcohol systems
Author(s) -
Libiszowski Jan,
Kowalski Adam,
Duda Andrzej,
Penczek Stanislaw
Publication year - 2002
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(200207)203:10/11<1694::aid-macp1694>3.0.co;2-j
Subject(s) - macromolecule , polymer chemistry , polymerization , ring opening polymerization , monomer , tetrahydrofuran , chemistry , polyester , caprolactone , lactide , solvent , polymer , organic chemistry , biochemistry
Ring‐opening polymerizations of ε ‐caprolactone (CL) and L , L ‐dilactide (LA) initiated by tin(II) octoate (Sn(Oct) 2 ) and zinc octoate (Zn(Oct) 2 ) and co‐initiated with butyl alcohol (BuOH) carried out in tetrahydrofuran as a solvent at 80 °C were studied. By means of MALDI‐TOF mass spectrometry, the formation of several populations of polyester macromolecules bearing various end‐groups was revealed, namely for poly( ε ‐caprolactone) (PCL): BuO(O)CPCLOH ( A ), BuO(O)CPCLOct ( B ), HO(O)CPCLOH ( C ), HO(O)CPCLOct ( D ), and PCL cyclics ( E ), and for poly( L ‐lactide) (PLA): BuO(O)CPLAOH ( A′ ), BuO(O)CPLAOct ( B′ ), HO(O)CPLAOH ( C′ ), and HO(O)CPLAOct ( D′ ) (where Bu = C 4 H 9 and Oct = O(O)CCH(C 2 H 5 )C 4 H 9 ). In these polymerizations the end‐groups in the originally formed macromolecules change slowly with time. In the LA/Sn(Oct) 2 /BuOH system at the beginning of polymerization almost exclusively macromolecules of the structure A′ are formed and then structures B′ , C′ , and D′ start to appear, however, after a period more than 300 times (at 80 °C) longer than that required for full monomer conversion, these macromolecules give exclusively esterified B′ and D′ chains. With Zn(Oct) 2 /BuOH all of these processes are much slower and less selective.Dependencies of mass fraction of macromolecules with various end‐groups on time in L , L ‐dilactide polymerization initiated with Sn(Oct) 2 /BuOH system. Symbols ▵, ▴, ○, • correspond to PLA populations A′ , B′ , C′ , and D′ .