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Cross‐Linked Poly( ε ‐caprolactone/ D , L ‐lactide) Copolymers with Elastic Properties
Author(s) -
Helminen Antti O.,
Korhonen Harri,
Seppälä Jukka V.
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/macp.200290039
Subject(s) - copolymer , polymer chemistry , monomer , polymerization , differential scanning calorimetry , oligomer , lactide , caprolactone , polymer , ring opening polymerization , hydrolysis , materials science , chemistry , composite material , organic chemistry , physics , thermodynamics
Cross‐linked ε ‐caprolactone (CL) and D , L ‐lactide (DLLA) copolymers with elastic properties were synthesized in three steps. First, the monomers were copolymerized in ring‐opening polymerization to obtain telechelic star‐shaped oligomers with almost completely random monomer distribution. The oligomers were methacrylated with methacrylic anhydride in the second step and cured in a third. Molar CL/DLLA compositions of 30/70, 50/50, 70/30, 90/10, and 100/0 were used to obtain elastic structures with a wide range of properties. The effect of the average length of the copolymer block on the properties of the networks was evaluated with three different co‐initiator contents (0.5, 1.0, and 2.0/100) in the oligomer synthesis. The oligomers were characterized by 13 C NMR spectroscopy, size‐exclusion chromatography (SEC), and differential‐scanning calorimetry (DSC). The formation of elastic networks was confirmed by the absence of a flow region in dynamic mechanical analysis (DMA), the increase in T g in DSC, and the full recovery of the sample dimensions after tensile testing. In addition, gel contents were high and the samples swelled in CH 2 Cl 2 . The networks possessed break stresses from 0.7–9.7 MPa with elongations from 80–350%. Networks with 100 or 90% of ε ‐caprolactone retained their form in vitro for 12 weeks, but an increase in lactide content made the networks more vulnerable to hydrolysis.Water absorption of the polymers during hydrolysis.