Lyophilized foams of end block containing absorbable polymers
Novel absorbable foams, lyophilizing solutions, and lyophilizing and annealing processes are disclosed. The foams are made from copolymers of glycolide and epsilon-caprolactone. The foams are useful in or as implantable medical devices.
1. An absorbable polymer foam, comprising:
a semicrystalline absorbable segmented block copolymer having a random center block segment of repeating units of polymerized glycolide and polymerized epsilon-caprolactone and an end block segment that comprises predominantly polymerized glycolide, wherein the mole ratio of polymerized glycolide to polymerized epsilon-caprolactone of the entire segmented copolymer is between about 55:45 to about 65:35, and having a mole ratio of polymerized glycolide to polymerized epsilon-caprolactone in the random center block segment between about 45:55 to about 52:48,
wherein the absorbable polymer foam has a compressive pressure at 2 mm height greater than 1.05 gf/mm 2 after 28 days of incubation in a buffer of pH 7.27 at 37° C. under continuous compression.
2. The foam of claim 1 wherein the copolymer has an inherent viscosity between about 0.5 dL/g and about 2.5 dl/g, as measured in a 0.1 g/dl solution of HFIP at 25° C.
3. The foam of claim 1 having a solid content from about 3 weight percent to about 20 weight percent.
4. The foam of claim 3 having the solid content between about 5 weight percent and 15 weight percent.
5. The foam of claim 1 having a thickness between about 0.5 mm to about 13 mm.
6. The foam of claim 5 having the thickness between about 1 mm and about 5 mm.
7. The foam of claim 1 prepared from 10 weight percent lyophilization solution.
8. The foam of claim 1 having a degradation coefficient less than −0.095 gf/(mm 2 day) when incubated in a buffer of pH 7.27 at 37° C. under continuous compression.
9. The foam of claim 8 prepared from 10 weight percent lyophilization solution.
10. The foam of claim 1 having mechanical integrity at least 30 days post-implantation.
11. The foam of claim 1 having mechanical integrity at least 60 days post-implantation.
12. The foam of claim 1 having a crystallinity level greater than about 10 percent.
13. The foam of claim 1 having a crystallinity level greater than about 20 percent.