Interpenetrating networks with covalent and Ionic Crosslinks

1. A composition comprising a self-healing interpenetrating networks hydrogel comprising a first network and a second network, wherein said first network comprises covalent crosslinks and said second network comprises ionic or physical crosslinks, wherein said first network comprises a polymer selected from the group consisting of polyacrylamide, poly(vinyl alcohol), poly(ethylene oxide) and its copolymers, polyethylene glycol (PEG), methacrylated PEG, and polyphosphazene; said second network comprises an alginate polymer; wherein the Young's modulus of the hydrogel is at least 10.0 kPa, wherein said interpenetrating networks hydrogel comprises a stretch value (λ) of about 21.

2. The composition of claim 1 , wherein said first network and said second network are covalently coupled.

3. A composition comprising a self-healing interpenetrating networks hydrogel comprising a first network and a second network, wherein said first network comprises covalent crosslinks and said second network comprises ionic or physical crosslinks, wherein said first network and said second network are covalently coupled, wherein said first network comprises a polymer selected from the group consisting of polyacrylamide, poly(vinyl alcohol), poly(ethylene oxide) and its copolymers, polyethylene glycol (PEG), methacrylated PEG, and polyphosphazene; said second network comprises an alginate polymer; and wherein the Young's modulus of the hydrogel is at least 10.0 kPa.

4. The composition of claim 3 , wherein said first network comprises a polyacrylamide polymer and said second network comprises an alginate polymer.

5. The composition of claim 4 , wherein the weight ratios of acrylamide to (acrylamide plus alginate) are from 66.67 wt. % to 94.12 wt. %.

6. The composition of claim 3 , wherein said interpenetrating polymer networks hydrogel comprises at least 30 wt % water.

7. The composition of claim 3 , wherein said interpenetrating polymer networks hydrogel comprises at least at least 80 wt % water.

8. The composition of claim 3 , wherein said interpenetrating polymer networks hydrogel comprises between 30-98 wt % water.

9. The composition of claim 3 , wherein said interpenetrating polymer networks hydrogel comprises a fracture toughness value of at least 10 J/m 2 .

10. The composition of claim 3 , wherein said interpenetrating polymer networks hydrogel comprises a fracture toughness value of at least 1000 J/m 2 .

11. The composition of claim 3 , wherein said interpenetrating polymer networks hydrogel comprises a fracture toughness value of at least 5000 J/m 2 .

12. The composition of claim 3 , wherein said interpenetrating polymer networks hydrogel comprises a fracture toughness value of at least 9000 J/m 2 .

13. The composition of claim 5 , wherein said interpenetrating networks hydrogel comprises a fracture toughness value of 10 J/m 2 to 9000 J/m 2 .

14. The composition of claim 3 , wherein said self-healing is characterized by a mechanical cycling property, wherein at least 50% energy density of a first loading is recovered after a period of rest of about 24 hours.

15. The composition of claim 3 , wherein said self-healing is characterized by a mechanical cycling property, wherein from 30% to 80% energy density of a first loading is recovered after a period of rest of about 24 hours.

16. The composition of claim 14 , wherein said rest comprises storage at a temperature greater than 20° C. and less than 200° C.

17. The composition of claim 15 , wherein said rest comprises storage at a temperature greater than 20° C. and less than 80° C.

18. The composition of claim 15 , wherein said rest comprises storage at a temperature of about 80° C.

19. The composition of claim 3 , wherein said interpenetrating networks hydrogel comprises a Young's modulus value of at least 300 kPa.

20. The composition of claim 3 , wherein said interpenetrating networks hydrogel comprises a rupture stretch value (λ) for non-notched hydrogels from 2 to 25.

21. The composition of claim 3 , wherein said interpenetrating networks hydrogel comprises a critical crack propagation stretch value (λ) for notched hydrogels from 2 to 17.

22. The composition of claim 3 , wherein said interpenetrating networks hydrogel comprises a stretch value (λ) of about 21.

23. The composition of claim 3 , wherein said interpenetrating networks hydrogel fully recovers its original length after unloading.

24. The composition of claim 3 , wherein said interpenetrating networks hydrogel comprises a constant ratio of 0.1 between loss modulus over storage modulus at a frequency of 0.01 Hz to 20 Hz.

25. The composition of claim 3 , wherein the fracture toughness of the interpenetrating polymer networks hydrogel is improved 900 times and 90 times compared to a polymer structure consisting essentially of alginate or acrylamide hydrogels, respectively.

26. The composition of claim 3 , wherein the ultimate tensile strength of the interpenetrating polymer networks hydrogel is improved 43.3 times and 13.8 times compared to a polymer structure consisting essentially of alginate or acrylamide hydrogels, respectively.

27. The composition of claim 3 , wherein rupture stretch of the interpenetrating polymer networks hydrogel is improved 19.2 times and 3.4 times compared to a polymer structure consisting essentially of alginate or acrylamide hydrogels, respectively.

28. The composition of claim 3 , wherein said interpenetrating networks hydrogel is fabricated in the form of a tissue augmentation or tissue replacement composition.

29. The composition of claim 28 , wherein said tissue augmentation or tissue replacement composition comprises a synthetic joint cartilage, spin disc, tendon, blood vessel, heart valve, muscle or skin.

30. The composition of claim 3 , wherein said interpenetrating networks hydrogel is used as a shock absorber or impact protector between biological or non-biological surfaces.

31. The composition of claim 3 , wherein said interpenetrating networks hydrogel is fabricated in the form of a soft robot, robotic skin, tunable lens, actuator, loud speaker membrane, or filter.

32. A method of making a self-healing interpenetrating networks hydrogel comprising a first network and a second network, wherein said first network comprises covalent crosslinks and said second network comprises ionic crosslinks; wherein said first network and said second network are covalently coupled, and wherein the Young's modulus of the hydrogel is at least 10.0 kPa, the method comprising

mixing an alginate and acrylamide polymer in a weight ratio of acrylamide to (acrylamide plus alginate) from 66.67 wt. % to 94.12 wt. %; and

contacting the mixture with a covalent crosslinking agent and an ionic crosslinking agent thereby making a self-healing interpenetrating networks hydrogel.

33. The method of claim 32 , wherein said method further comprises a thermal treatment prior to contacting said mixture with a crosslinking agent.

34. The method of claim 33 , wherein said thermal treatment comprises a temperature of 20° C.−36° C.

35. The method of claim 33 , wherein said covalent crosslinking agent comprises N,N-methylenebisacrylamide (MBAA) and wherein said ionic crosslinking agent comprises CaSO 4 .

36. A composition comprising a self-healing interpenetrating networks hydrogel comprising a first network and a second network, wherein said first network comprises covalent crosslinks and said second network comprises ionic or physical crosslinks, wherein said first network and said second network are covalently coupled, wherein said first network comprises a polymer selected from polyethylene glycol (PEG) and methacrylated PEG and said second network comprises an alginate polymer.

37. The composition of claim 36 , wherein said interpenetrating polymer networks comprises a fracture toughness value of at least 1000 J/m 2 .

38. The composition of claim 36 , wherein said self-healing is characterized by a mechanical cycling property, wherein at least 50% energy density of a first loading is recovered after a period of rest of about 24 hours.

39. A composition comprising a self-healing interpenetrating networks hydrogel comprising a first network and a second network, wherein said first network comprises covalent crosslinks and said second network comprises ionic or physical crosslinks, wherein said first network comprises a polymer selected from the group consisting of polyacrylamide, poly(vinyl alcohol), poly(ethylene oxide) and its copolymers, polyethylene glycol (PEG), methacrylated PEG, and polyphosphazene; said second network comprises an alginate polymer; wherein the Young's modulus of the hydrogel is about 5 MPa.

40. A composition comprising a self-healing interpenetrating networks hydrogel comprising a first network and a second network, wherein said first network comprises covalent crosslinks and said second network comprises ionic or physical crosslinks, wherein said first network and said second network are covalently coupled, wherein said first network comprises a polymer selected from the group consisting of polyethylene glycol (PEG) and methacrylated PEG; said second network comprises an alginate polymer; and wherein the Young's modulus of the hydrogel is at least 10.0 kPa.