Biomaterial

1. A viscoelastic biostable foam comprising a triblock copolymer of formula residue I

wherein:

each represents a point of attachment to a urethane or urea linkage;

each of X and Y is independently an ether, an ester, a carbonate, or a fluorohydrocarbon, or mixture thereof;

each of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 is independently selected from one or more of R, OR, —CO 2 R, a fluorinated hydrocarbon, a polyether, a polyester or a fluoropolymer

each R is independently hydrogen, an optionally substituted C 1-20 aliphatic group, or an optionally substituted group selected from phenyl, 8-10 membered bicyclic aryl, a 4-8 membered monocyclic saturated or partially unsaturated heterocyclic ring having 1-2 heteroatoms independently selected from nitrogen, oxygen, or sulphur, or 5-6 membered monocyclic or 8-10 membered bicyclic heteroaryl group having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur;

each of m n and p is independently 2 to 100; and

each of L 1 and L 2 is independently a bivalent C 1-20 hydrocarbon chain wherein 1-4 methylene units of the hydrocarbon chain are optionally and independently replaced by —O—, —S—, —N(R)—, —C(O)—, —C(O)N(R)—, —N(R)C(O)—, —SO 2 — —SO 2 N(R)—, —N(R)SO 2 —, —OC(O)—, —C(O)O—, or a bivalent cycloalkylene, arylene, heterocyclene, or heteroarylene, provided that neither of L 1 nor L 2 comprises a urea or urethane moiety.

2. The viscoelastic biostable film according to claim 1 wherein the triblock copolymer residue is selected from:

3. The viscoelastic biostable foam according to claim 1 , wherein at least one of (a), (b), (c), (d), (e), (f), (g) or (h) applies:

(a) said foam is stable to gastric fluid for at least 3 months, for at least 4 months, for at least 5 months, for at least 6 months, for at least 7 months, for at least 8 months, for at least 9 months, for at least 10 months, for at least 11 months, or for at least one year,

(b) said foam takes up less than about 5%, less than about 10%, less than about 15%, less than about 20%, less than about 25%, or less than about 30% by weight of water at equilibrium,

(c) said foam has an elongation capacity of about 200-1200%,

(d) said foam has a tensile strength of about 0.1 to about 1.0 MPa,

(e) said foam has a density of 0.1 to 1.5 g/cm 3 ,

(f) said foam has a density of 0.3 to 1.2 g/cm 3 ,

(g) said foam has a density of 0.8 to 0.9 g/cm 3 , or

(h) said foam has a density of 0.5 to 0.6 g/cm 3 .

4. The viscoelastic biostable foam according to claim 1 , wherein X is selected from ethylene oxide, difluoromethyl ethylene oxide, trifluoromethyl ethylene oxide, propylene oxide, difluoromethyl propylene oxide, propylene oxide, trifluoromethyl propylene oxide, butylene oxide, tetramethylene ether glycol, tetrahydrofuran, oxymethylene, ether ketone, etherether ketone, dimethylsiloxane, diethylsiloxane, methyl phenyl siloxane, diphenyl siloxane, methyl di-fluoroethyl siloxane, methyl tri-fluoroethyl siloxane, phenyl di-fluoroethyl siloxane, phenyl tri-fluoroethyl siloxane, ethylene terephthalate, ethylene terephthalate ionomer, ethylene naphthalate, methylene naphthalate, butylene teraphalate, butylene naphthalate, or polycarbonate.

5. The viscoelastic biostable foam according to claim 4 , wherein Y is selected from ethylene oxide, difluoromethyl ethylene oxide, trifluoromethyl ethylene oxide, propylene oxide, difluoromethyl propylene oxide, propylene oxide, trifluoromethyl propylene oxide, butylene oxide, tetramethylene ether glycol, tetrahydrofuran, oxymethylene, ether ketone, etherether ketone, dimethylsiloxane, diethylsiloxane, methyl phenyl siloxane, diphenyl siloxane, methyl di-fluoroethyl siloxane, methyl tri-fluoroethyl siloxane, phenyl di-fluoroethyl siloxane, phenyl tri-fluoroethyl siloxane, ethylene terephthalate, ethylene terephthalate ionomer, ethylene naphthalate, methylene naphthalate, butylene teraphalate, butylene naphthalate, or polycarbonate.

6. The viscoelastic biostable foam according to claim 5 , wherein X and Y are the same and selected from ethylene oxide, difluoromethyl ethylene oxide, trifluoromethyl ethylene oxide, propylene oxide, difluoromethyl propylene oxide, propylene oxide, trifluoromethyl propylene oxide, butylene oxide, tetramethylene ether glycol, tetrahydrofuran, oxymethylene, ether ketone, etherether ketone, dimethylsiloxane, diethylsiloxane, methyl phenyl siloxane, diphenyl siloxane, methyl di-fluoroethyl siloxane, methyl tri-fluoroethyl siloxane, phenyl di-fluoroethyl siloxane, phenyl tri-fluoroethyl siloxane, ethylene terephthalate, ethylene terephthalate ionomer, ethylene naphthalate, methylene naphthalate, butylene teraphalate, butylene naphthalate, or polycarbonate.

7. The viscoelastic biostable foam according to claim 1 , wherein X and Y are both the same.

8. The viscoelastic biostable foam according to claim 1 wherein X and Y are both an ether.

9. The viscoelastic biostable foam according to claim 1 , wherein X and Y are both propylene oxide.

10. The viscoelastic biostable foam according to claim 1 , wherein

(a) m and p are each independently between 2 and 50 and n is between 2 and 20,

(b) m and p are each independently between 2 and 30 and n is between 2 and 20, or

(c) each of m, n, and p are 8-16.

11. The viscoelastic biostable foam according to claim 1 , wherein

(a) one or more of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 is independently an optionally substituted C 1-6 alkyl,

(b) each of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 is independently methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, isobutyl, or cyclobutyl,

(c) each of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 is independently mono-, di-, tri, or perfluorinated methyl, ethyl, propyl, butyl, or phenyl, or

(d) each of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 is independently methyl, ethyl, propyl, trifluoromethyl, trifluoroethyl, or trifluoropropyl.

12. The viscoelastic biostable foam according to claim 1 wherein at least one of (a), (b), (c), (d), (e) or (f) applies:

(a) each of L 1 and L 2 is independently a bivalent C 1-20 alkylene chain,

(b) each of L 1 and L 2 is independently a bivalent C 1-10 alkylene chain,

(c) each of L 1 and L 2 is independently a bivalent methylene, ethylene, propylene, or butylene chain,

(d) each of L 1 and L 2 is independently —OCH 2 —, —OCH 2 CH 2 —, —OCH 2 CH 2 CH 2 —, or —OCH 2 CH 2 CH 2 CH 2 —,

(e) each of L 1 and L 2 is independently a bivalent C 1-6 alkylene chain wherein at least one methylene unit of the chain is replaced by —O— and at least one methylene unit of the chain is replaced by a bivalent arylene, or

(f) each of L 1 and L 2 is independently —OCH 2 -phenylene-, —OCH 2 CH 2 -phenylene-, —OCH 2 CH 2 -phenylene-CH 2 —, or —OCH 2 CH 2 CH 2 CH 2 -phenylene-.