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Block copolymers of poly( L ‐lactide) and poly(ε‐caprolactone) or poly(ethylene glycol) prepared by reactive extrusion
Author(s) -
Stevels W. M.,
Bernard A.,
Witte P. Van De,
Dijkstra P. J.,
Feijen J.
Publication year - 1996
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/(sici)1097-4628(19961121)62:8<1295::aid-app20>3.0.co;2-5
Subject(s) - lactide , polymer chemistry , copolymer , reactive extrusion , materials science , transesterification , ethylene glycol , polyester , ring opening polymerization , polymerization , monomer , caprolactone , polymer , methanol , chemistry , organic chemistry , composite material
Blends of poly(L‐lactide) (PLLA) and poly(ε‐caprolactone) (PCL) were prepared in a co‐rotating twin screw miniextruder (40 rpm, 200°). It was attempted to prepare multiblock copolymers by allowing a controlled number of transesterification reactions. Various cat‐alysts ( n ‐Bu 3 SnOMe, Sn(Oct) 2 , Ti(OBu) 4 , Y(Oct) 3 , para ‐toluene sulphonic acid) were introduced to promote these transesterification reactions. However, PLLA degradation by ring‐closing depolymerization was the dominant reaction in every case. Alternatively, after showing that L‐lactide can be conveniently polymerized in the extruder, L‐lactide and hy‐droxyl functionalized prepolymers of PCL or poly(ethylene glycol) (PEG) were fed to the extruder in the presence of stannous octoate. Monomer conversions of over 90% and effective transformation of all hydroxyl end groups present were generally reached. Di‐and triblock copolymers could be prepared in this way with characteristics very similar to polymers prepared in a batch‐type process, but with considerably reduced reaction times in a fashion, which is, in principle, scaleable to a continuous process for the production of such block copolymers. © 1996 John Wiley & Sons, Inc.