Bioabsorbable Polymeric Compositions and Medical Devices
The present invention comprises a stent forming a plurality of meandering elements comprising a blend formed from a polymer. The polymer comprises poly-L-lactide, poly-D-lactide or mixtures thereof and a copolymer moiety comprising poly-L-lactide or poly-D-lactide linked with ε-caprolactone or trimethylcarbonate. The poly-L-lactide or poly-D-lactide sequence in the copolymer moiety is random with respect to the distribution of ε-caprolactone or trimethylcarbonate and the copolymer moiety molecular weight ranges from about 1.2 IV to about 4.8 IV. The meandering elements may be stretched to a modulus ranging from about 250000 PSI to about 550,000 PSI, one segment of the meandering element has a decreased cross-sectional area and may have a wide-angle X-ray scattering (WAXS) 2θ values of ranging from about 1 to about 35. In various embodiment, two, three or n segments of the meandering element have a decreased cross-sectional area and may also have a wide-angle X-ray scattering (WAXS) 2θ values of ranging from about 1 to about 35 after stretching. In another embodiment, all segments of the meandering element have a decreased cross-sectional area and may also have a wide-angle X-ray scattering (WAXS) 2θ values of ranging from about 1 to about 35 after stretching. The meandering element may comprise a helical winding, a circumferential winding or stent ringlet. The properties of the bioabsorbable polymers allow for both crimping and expansion of the stent. The crystal properties of the bioabsorbable polymers may change during crimping and/or expansion allowing for improved mechanical properties such as tensile strength and slower degradation kinetics.
1 . A stent comprising a blend formed from poly-L-lactide, poly-D-lactide or mixtures thereof and a copolymer moiety comprising poly-L-lactide or poly-D-lactide linked with ε-caprolactone or trimethylcarbonate wherein, the poly-L-lactide or poly-D-lactide sequence in the copolymer moiety is random with respect to the distribution of ε-caprolactone or trimethylcarbonate and where the wide-angle X-ray scattering (WAXS) exhibits 2θ values of about 16.48 and about 18.76.
2 . The stent of claim 1 wherein the co-polymer moiety comprises poly-L-lactide or poly-D-lactide linked with ε-caprolactone.
3 . The stent of claim 2 wherein the polymer moiety comprises poly-L-lactide.
4 . The stent of claim 2 wherein the polymer moiety comprises poly-D-lactide.
5 . The stent of claim 1 wherein the co-polymer moiety is poly-L-lactide or poly-D-lactide linked with TMC and the molecular weight of the co-polymer ranges from about 1.2 IV to about 2.6 IV.
6 . The stent of claim 2 wherein the molecular weight of the co-polymer ranges from about 0.8 to about 6.0.
7 . The stent of claim 1 wherein the WAXS 2θ values further comprise peaks at about 11.92, about 20.66, about 22.24 and about 28.84.
8 . The stent of claim 1 comprising a blend having about 20%-45% (w/w) poly-L-lactide, about 35% (w/w) to about 50% (w/w) poly-D-lactide and about 10% (w/w) to about 35% (w/w) poly L-lactide-co-TMC or poly-L-lactide-ε-caprolactone.
9 . The stent of claim 1 wherein the poly-L-lactide or poly-D-lactide ranges from about 20% (w/w) to about 95% (w/w).
10 . The stent of claim 9 wherein the poly-L-lactide or poly-D-lactide ranges from about 50% (w/w) to about 95% (w/w).
11 . The stent of claim 10 wherein the poly-L-lactide ranges from about 60% (w/w) to about 95% (w/w).
12 . The stent of claim 11 wherein the poly-L-lactide ranges from about 70% (w/w) to about 80% (w/w).
13 . The stent of claim 1 wherein greater than 7 L-lactides or D-lactides are arrayed sequentially in the copolymer moiety.
14 . A stent comprising a blend formed from poly-L-lactide, poly-D-lactide or mixtures thereof and a copolymer moiety comprising poly-L-lactide or poly-D-lactide linked with ε-caprolactone or trimethylcarbonate wherein, the poly-L-lactide or poly-D-lactide sequence in the copolymer moiety is random with respect to the distribution of ε-caprolactone or trimethylcarbonate, wherein there is at least about 95% (w/w) amorphous material in the stent.
15 . The stent of claim 14 wherein there is at least about 98% (w/w) amorphous material.
16 . The stent of claim 15 wherein there is at least about 99% (w/w) amorphous material.
17 . The stent of claim 1 wherein percent crystallinity ranges from about 0% (w/w) to about 10% (w/w).
18 . The stent of claim 1 wherein the percent crystallinity ranges from about 20% (w/w) to about 70% (w/w).
19 . The stent of claim 18 wherein the percent crystallinity ranges from about 30% (w/w) to about 60% (w/w).
20 . The stent of claim 19 wherein the percent crystallinity ranges from about 30% (w/w) to about 60% (w/w).
21 . A stent comprising a blend formed from poly-L-lactide, poly-D-lactide or mixtures thereof and a copolymer moiety comprising poly-L-lactide or poly-D-lactide linked with ε-caprolactone or trimethylcarbonate wherein, the poly-L-lactide or poly-D-lactide sequence in the copolymer moiety is random with respect to the distribution of ε-caprolactone or trimethylcarbonate and where the wide-angle X-ray scattering (WAXS) exhibits 2θ values of about 16.65 and about 18.96.
22 . The stent of claim 21 wherein the WAXS 2θ values further comprise about 12.00, about 14.80, about 20.67, about 22.35, about 23.92, about 24.92, about 29.16 and about 31.28.
23 . The stent of claim 1 wherein the T m peaks occur at about 180° C. and about 217° C.
24 . The stent of claim 21 wherein the T m peaks occur at about 178° C. and about 220° C.
25 . The stent of claim 21 wherein about T g is 61° C. and about 128° C.