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Syntheses of cyclic poly(lactones) by zwitterionic ring opening polymerization catalyzed by N‐heterocyclic carbene
Author(s) -
Vishwa Prasad Aitha,
Yinghuai Zhu
Publication year - 2012
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.38569
Subject(s) - ring opening polymerization , polymer chemistry , carbene , polymerization , thermogravimetric analysis , copolymer , catalysis , monomer , differential scanning calorimetry , chemistry , gel permeation chromatography , polymer , materials science , organic chemistry , physics , thermodynamics
Synthesis of cyclic biopolymers from renewable monomers remains a big challenge because of lack of efficient catalysts. The organocatalyst of N‐heterocyclic carbene (NHC), (+)‐1‐methyl‐3‐menthoxymethyl imidazol‐2‐ylidene, is used to prepare cyclic polylactones including poly(ε‐caprolactone) (poly(ε‐CL)), poly(δ‐valearolactone) (poly(δ‐VL)), and poly(ε‐caprolactone‐ co ‐δ‐valearolactone) (poly(ε‐CL‐ co ‐δ‐VL)) via zwitterionic ring opening polymerization. The NHC catalyst is founded a highly efficient organic catalyst for the polymerization. The resulting cyclic polymers show a melting temperature ( T m ) in a range of 20–60°C, which is dramatically lower than the T m of cyclic poly(lactide) ( T m = 120–150°C). The resulting copolymer, cyclic poly(ε‐CL‐ co ‐δ‐VL) owns high molecular weight comparing with corresponding linear poly(ε‐CL‐ co ‐δ‐VL) produced by other catalysts. The synthesized cyclic homo and copolymers were characterized by 1 H‐, 13 C‐NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry–thermogravimetric analysis and matrix‐assisted laser desorption ionization‐time of flight mass spectrometry. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013