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Ring‐closing depolymerization of poly(ε‐caprolactone)
Author(s) -
Nelißen Marion,
Keul Helmut,
Höcker Hartwig
Publication year - 1995
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/macp.1995.021960521
Subject(s) - caprolactone , depolymerization , trimer , polymer chemistry , dimer , chemistry , catalysis , toluene , oligomer , ring opening polymerization , polymerization , copolymer , reaction mechanism , polymer , organic chemistry
Ring‐closing depolymerization of poly(ε‐caprolactone) in toluene solution with catalytic amounts of Bu 2 Sn(OMe) 2 results in a mixture of cyclic oligomers, the equilibrium concentration of which corresponds to the concentration predicted according to the Jacobson‐Stockmayer theory. ε‐Caprolactone, however, is absent from this reaction mixture. When poly(ε‐caprolactone) is depolymerized in the melt at 260°C in the presence of a catalyst, beside ε‐caprolactone its cyclic dimer and trimer are distilled off. The composition is dependent on the catalyst used, e.g., Bu 2 Sn(OMe) 2 produces 95,4 wt.‐% of ε‐caprolactone and 3,7 wt.‐% of its dimer while with Ti(OiPr) 4 (iPr: isopropyl) 51,4 wt.‐% ε‐caprolactone and 49,6 wt.‐% of its dimer are obtained. Block copolymers containing poly(ε‐caprolactone) result in a similar product distribution, however, the second block may influence the rate of decomposition. The activation energy of the catalysed (0,5 mol‐% Bu 2 Sn(OMe) 2 ) and uncatalysed ring‐closing depolymerization were determined to be 63 kJ/mol, and 87 kJ/mol, respectively.