Block copolymer compositions

1. A hydrogenated block copolymer comprising block copolymer components (a) and (b), wherein

block copolymer component (a) is a selectively hydrogenated block copolymer comprising one or more structures A-B-A, (A-B-A)nX, A-(B-A)n, and (A-B)nX;

block copolymer component (b) is a selectively hydrogenated block copolymer comprising one or more structures C-D, D-C-D, and (D-C-)nX; and

wherein “n” is 1-30, and “X” is a residue of a coupling agent;

wherein before hydrogenation,

A is a polymer block of a vinyl aromatic monomer, having a peak molecular weight (Mp) of 14-60 kg/mol,

B is a polymer block comprising 60-100 mol % of one or more conjugated dienes, and 0-40 mol % of a vinyl aromatic monomer;

C is a polymer block of a vinyl aromatic monomer, having a peak molecular weight of 1-8 kg/mol; and

D is a polymer block comprising 60-100 mol % of one or more conjugated dienes, and 0-40 mol % of a vinyl aromatic monomer;

wherein after hydrogenation,

80 to 100 mol % of the polymerized diene units in the polymer blocks B and D are reduced; and

0-20 mol % of the polymerized vinyl aromatic monomer units in the polymer blocks A, B, C and D are reduced;

wherein the vinyl aromatic monomers of the polymer blocks A, B, C and D are independently same or different and the conjugated diene monomers for the polymer blocks B and D are independently same or different;

wherein the block copolymer component (a) has a peak molecular weight of 100-1,000 kg/mol and the block copolymer component (b) has a peak molecular weight of 6-60 kg/mol; and

wherein the hydrogenated block copolymer has a compression set after 24 hrs. at 70° C. of less than 50%, measured according to ASTM D395, an apparent viscosity measured at 230° C., and a shear rate of 5000/s of <70 Pa·s.

2. The hydrogenated block copolymer of claim 1 , wherein the components (a) and (b) are in a weight ratio ranging from 1:0.1 to 1:5, respectively.

3. The hydrogenated block copolymer of claim 1 , wherein the block copolymer component (a) has a peak molecular weight of 150-800 kg/mol.

4. The hydrogenated block copolymer of claim 1 , wherein the block copolymer component (b) has a peak molecular weight of 10-50 kg/mol.

5. The hydrogenated block copolymer of claim 1 , wherein the polymer block A forms 18-40 wt. % of the overall weight of component (a).

6. The hydrogenated block copolymer of claim 1 , wherein before hydrogenation,

A is a polymer block of a vinyl aromatic monomer, having a peak molecular weight (Mp) of 20-50 kg/mol,

B is a polymer block comprising 70-90 mol % of one or more conjugated dienes, and 10-30 mol % of a vinyl aromatic monomer;

C is a polymer block of a vinyl aromatic monomer, having a peak molecular weight of 2-6 kg/mol; and

D is a polymer block comprising 70-90 mol % of one or more conjugated dienes, and 10-30 mol % of a vinyl aromatic monomer.

7. The hydrogenated block copolymer of claim 1 , wherein after hydrogenation,

85 to 98 mol % of the polymerized diene units in the polymer blocks B and D are reduced; and

2-15 mol % of the polymerized vinyl aromatic monomer units in the polymer blocks A, B, C and D are reduced.

8. The hydrogenated block copolymer of claim 1 , wherein the polymer blocks B and D comprise polymerized diene units derived from the same conjugated diene, and wherein the conjugated diene is selected from the group consisting of 1,3-butadiene, isoprene, myrcene, farnesene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and combinations thereof.

9. The hydrogenated block copolymer of claim 1 , wherein the polymer blocks A, B, C, and D independently comprise polymerized vinyl aromatic monomer units derived from the same vinyl aromatic monomer, wherein the vinyl aromatic monomer units is selected from the group consisting of styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, alpha-methylstyrene, vinylnaphthalene, vinyltoluene, vinylxylene, and combinations thereof.

10. The hydrogenated block copolymer of claim 1 , wherein the hydrogenated block copolymer has a compression set after 24 hrs. at 70° C. of less than 40%, measured according to ASTM D395.

11. The hydrogenated block copolymer of claim 1 , wherein the hydrogenated block copolymer has an apparent viscosity measured at 230° C. and a shear rate of 5000/s of <50 Pa·s.

12. A thermoplastic elastomer blend comprising 100 parts by weight of the hydrogenated block copolymer of claim 1 , and 95 to 1 parts by weight of a semi-crystalline polyolefin.

13. The thermoplastic elastomer blend of claim 12 , further comprising up to 100 parts, per 100 parts of the blend, at least an additive selected from, a polyphenylene ether, an organic filler, an inorganic filler, carbon black, a flame retardant, an antioxidant, a UV stabilizer, a dye, and a surface agent.

14. The thermoplastic elastomer blend of claim 12 , wherein the thermoplastic elastomer blend has a compression set, measured after 24 hours at 70° C. according to ASTM D395, of less than 45%.

15. The thermoplastic elastomer blend of claim 12 , wherein the thermoplastic elastomer blend has a level of extractables measured by UV on a pre-treated sample, according to YBB00042005, of <0.1% absorbance.

16. The thermoplastic elastomer blend of claim 12 , wherein the thermoplastic elastomer blend has an apparent viscosity of <70 Pa·s, measured via capillary rheometry at a shear rate of 5000/s at 200° C.

17. The thermoplastic elastomer blend of claim 12 , wherein the thermoplastic elastomer blend is oil free and phthalate free.

18. An article comprising the thermoplastic elastomer blend of claim 12 .

19. The article of claim 18 , selected from a sheet, a molded article, a profile extrusion, a film, a medical bag, a medical tube, a vial stopper, and an IV stopper.