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In vitro degradation studies and mechanical behavior of poly(ε-caprolactone-co-δ-valerolactone) and poly(ε-caprolactone-co-L-lactide) with random and semi-alternating chain microstructures.

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Title: In vitro degradation studies and mechanical behavior of poly(ε-caprolactone-co-δ-valerolactone) and poly(ε-caprolactone-co-L-lactide) with random and semi-alternating chain microstructures.
Authors: Fernández, Jorge1 jorge.fernandez@ehu.es, Etxeberria, Agustin2, Sarasua, Jose-Ramon1
Source: European Polymer Journal. Oct2015, Vol. 71, p585-595. 11p.
Subjects: Biodegradation, Polymers, Polycaprolactone, Biomedical engineering, Hydrolysis, Homopolymerizations, Glass transitions
Abstract: Poly(ε-caprolactone) (PCL) is one of the most common polymers employed in the biomedical field owing to its outstanding properties, however, it degrades slowly, at a rate ( K Mw ) of 0.0010 days −1 at 37 °C. The incorporation of a second comonomer and the tailoring of more disordered chain microstructures were tested to accelerate hydrolysis. Both ε-caprolactone-co-δ-valerolactone and ε-caprolactone-co- L -lactide copolymers, synthesized with random ( R ∼ 1) and semi-alternating ( R → 2) distribution of sequences, exhibited faster degradation rates than PCL. ε-CL-co-δ-VAL, with ε-CL molar contents ranging from 76% to 85%, possessed K Mw values of between 0.0052 and 0.0033 days −1 , whereas the copolymers based on lactide, with 88–94% of ε-CL, had a K Mw 6–10 times higher than that of the homopolymer. The crystalline phase played a pivotal role in water absorption and degradation process, but was also responsible for the mechanical behavior of these low glass transition temperature polymers. At 21 °C all the copolymers showed excellent ductility (strain at break > 1000%) and improved flexibility compared to PCL (with secant modulus between 56 and 185 MPa). At body temperature (37 °C) it was only possible to measure the properties of the copolymers which had a T m above 52 °C or a high enough melting enthalpy (>33 J g −1 ). Moreover, at this temperature, PCL and the ε-CL-co- L -LA with a ε-CL content higher than 88% exhibited lower stress related properties. Nevertheless, the mechanical performance at both temperatures of these poly(ε-CL-co- L -LA), in addition to their upgraded biodegradability, make them potential substitutes for PCL. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Poly(ε-caprolactone) (PCL) is one of the most common polymers employed in the biomedical field owing to its outstanding properties, however, it degrades slowly, at a rate ( K Mw ) of 0.0010 days −1 at 37 °C. The incorporation of a second comonomer and the tailoring of more disordered chain microstructures were tested to accelerate hydrolysis. Both ε-caprolactone-co-δ-valerolactone and ε-caprolactone-co- L -lactide copolymers, synthesized with random ( R ∼ 1) and semi-alternating ( R → 2) distribution of sequences, exhibited faster degradation rates than PCL. ε-CL-co-δ-VAL, with ε-CL molar contents ranging from 76% to 85%, possessed K Mw values of between 0.0052 and 0.0033 days −1 , whereas the copolymers based on lactide, with 88–94% of ε-CL, had a K Mw 6–10 times higher than that of the homopolymer. The crystalline phase played a pivotal role in water absorption and degradation process, but was also responsible for the mechanical behavior of these low glass transition temperature polymers. At 21 °C all the copolymers showed excellent ductility (strain at break > 1000%) and improved flexibility compared to PCL (with secant modulus between 56 and 185 MPa). At body temperature (37 °C) it was only possible to measure the properties of the copolymers which had a T m above 52 °C or a high enough melting enthalpy (>33 J g −1 ). Moreover, at this temperature, PCL and the ε-CL-co- L -LA with a ε-CL content higher than 88% exhibited lower stress related properties. Nevertheless, the mechanical performance at both temperatures of these poly(ε-CL-co- L -LA), in addition to their upgraded biodegradability, make them potential substitutes for PCL. [ABSTRACT FROM AUTHOR]
ISSN:00143057
DOI:10.1016/j.eurpolymj.2015.09.001