Crosslinked poly(ester anhydride)s based on poly(ε-caprolactone) and polylactide oligomers

• Published in: Journal of polymer science. Part A, Polymer chemistry Polymer chemistry, 2003-12, Vol.41 (23), p.3788-3797
• Main Authors: Helminen, Antti O., Korhonen, Harri, Seppälä, Jukka V.
• Format: Article
• Language: English
• Subjects: anhydrides; biodegradable; crosslinking; degradation; polyesters
• ISSN: 0887-624X; 1099-0518
• DOI: 10.1002/pola.10951

Resorbable poly(ester anhydride) networks based on ε‐caprolactone, L‐lactide, and D,L‐lactide oligomers were synthesized. The ring‐opening polymerization of the monomers yielded hydroxyl telechelic oligomers, which were end‐functionalized with succinic anhydride and reacted with methacrylic anhydride to yield dimethacrylated oligomers containing anhydride bonds. The degree of substitution, determined by 13C NMR, was over 85% for acid functionalization and over 90% for methacrylation. The crosslinking of the oligomers was carried out thermally with dibenzoyl peroxide at 120 °C, leading to polymer networks with glass‐transition temperatures about 10 °C higher than those of the constituent oligomers. In vitro degradation tests, in a phosphate buffer solution (pH 7.0) at 37 °C, revealed a rapid degradation of the networks. Crosslinked polymers based on lactides exhibited high water absorption and complete mass loss in 4 days. In ε‐caprolactone‐based networks, the length of the constituent oligomer determined the degradation: PCL5‐AH, formed from longer poly(ε‐caprolactone) (PCL) blocks, lost only 40% of its mass in 2 weeks, whereas PCL10‐AH, composed of shorter PCL blocks, completely degraded in 2 days. The degradation of PCL10‐AH showed characteristics of surface erosion, as the dimensions of the specimens decreased steadily and, according to Fourier transform infrared, labile anhydride bonds were still present after 90% mass loss. © 2003 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3788–3797, 2003 Crosslinked poly(ester anhydride)s were prepared from ε‐caprolactone‐, L‐lactide‐, and D,L‐lactide‐based oligomers. After functionalizations with succinic and methacrylic anhydride, the oligomers possessed crosslinkable methacrylate groups and labile anhydride bonds. Cured polymer networks degraded in hydrolysis tests in a matter of days through a two‐step degradation profile, in which the rapid cleavage of anhydride bonds was followed by the dissolution or degradation of the polyester blocks. Characteristics of surface erosion were observed in the degradation of a network prepared from small PCL oligomers. The network contained labile anhydride bonds almost to full mass loss.