Absorbable copolymers with improved thermal stability

Abstract

The present invention relates to absorbable block copolymers with improved characteristics including thermal stability, molecular weight consistency, inherent viscosity retention following melt extrusion, and fibers made from the polymers exhibit increased strength.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to absorbable copolymers with improved characteristics including thermal stability, molecular weight consistency, inherent viscosity retention following melt extrusion, as well as methods of manufacturing the improved absorbable copolymers. The present invention further relates to absorbable fibrous constructs which may be used for controlled drug delivery.[0002]Previous work in the polymer field, such as U.S. Pat. No. 6,462,169 to Shalaby, discloses polyaxial block copolyesters containing high glycolide end-grafts. However, the polymers resulting from this disclosure lack various properties compared to the current disclosure, such as thermal stability, molecular weight consistency, and inherent viscosity retention following melt extrusion. Further, fibers made from the '169 disclosure lack the strength and toughness exhibited by fibers made from the polymers of the present disclosure. Moreover, the polymers disclosed by...

AI Technical Summary

Benefits of technology

The present invention provides an absorbable aliphatic polyester copolymer with improved properties. The copolymer includes a polyaxial core with at least three axes and flexible linking segments. The flexible linking segments can be derived from the same pre-polymer and the same crystallizable cyclic monomer. The pre-polymer can be formed from a combination of L,L-lactide and D,L-lactide, glycolide, substituted glycolides, para-dioxanone, 1,5-dioxepan-2-one, trimethylene carbonate, ε-caprolactone, alpha-Angelica lactone, gamma-valerolactone, or delta-valerolactone. The copolymer can be used for various applications such as absorbable barrier, web, mesh, or fabric. The method for producing the copolymer involves charging a reactor with a monomer, an initiator, and a catalyst and stirring the monomer to form a homogeneous mixture prepolymer.

Problems solved by technology

However, the polymers resulting from this disclosure lack various properties compared to the current disclosure, such as thermal stability, molecular weight consistency, and inherent viscosity retention following melt extrusion.

Further, fibers made from the '169 disclosure lack the strength and toughness exhibited by fibers made from the polymers of the present disclosure.

The polymers resulting from the '229 disclosure are not only formed from a solid state synthesis using more catalyst but lack the thermal stability, molecular weight consistency, and inherent viscosity retention following melt extrusion characteristics of polymers made pursuant to the current disclosure.

Furthermore, the '229 reference is also limited to polymer compositions synthesized in a single step reaction.

However, the polymers resulting from the '065 disclosure lack the thermal stability, molecular weight consistency, inherent viscosity retention following melt extrusion, and the improved fiber strength of the polymers of the current disclosure.

Further, Wang fails to disclose flexible linking segments as disclosed herein.

However, these compositions are not symmetrical and are intentionally designed to have unsaturated bonds distributed at particular locations along the polymer arms so that the polymers are more oxidatively stable.

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