The invention relates to a material formed by a polymer substrate and a hydrogel based on vinyl-lactams and ionic methacrylates. The invention also relates to a method for producing this material and to the use thereof for cell culture and cell monolayer engineering, for preparing 3D scaffolds and manufacturing thermosensitive mechanical actuators.
1. A product comprising: a) a polymeric substrate and b) a hydrogel based on vinyl-lactam type monomers, without methacrylates or with ionic methacrylates, and at least two crosslinkers,characterized in that there is an interface between the substrate and the hydrogel, an interface formed by a gradient of both, the substrate and the hydrogel network -both forming a semi-interpenetrated network structure-. 2. A product according to claim 1, comprising: a) a polymeric substrate and b) a hydrogel based on vinyl-lactam type monomers, without methacrylates, wherein the vinyl-lactam is vinylcaprolactam, the polymeric substrate is nylon, and the two crosslinkers are ethylene glycol -C1- and 3,3'-(propyl)-di-1-vinyl-2-pyrrolidone -C2-, or a) polymeric substrate and b) a hydrogel based on vinyl-lactam type monomers, with ionic methacrylates, and at least two crosslinkers,characterized in that there is an interface between the substrate and the hydrogel, an interface formed by a gradient of both the substrate and the hydrogel network -both forming a semi-interpenetrated network structure-. 3. A product according to claim 1, comprising: a) a polymeric substrate and b) a hydrogel based on vinyl-lactam type monomers, with ionic methacrylates, and at least two crosslinkers,characterized in that there is an interface between the substrate and the hydrogel, an interface formed by a gradient of both the substrate and the hydrogel network -both forming a semi-interpenetrated network structure-. 4. Product according to claim 3, wherein the polymeric substrate is selected from polystyrene, polymethyl methacrylate, nylon, polycarbonate, poly(vinylchloride), polylactic acid and polycaprolactone. 5. Product according to claim 3, wherein the polymeric substrate is nylon, polystyrene or polycarbonate. 6. Product according to claim 3, wherein the vinyl-lactam is selected vinylcaprolactam or vinylpyrrolidone. 7. Product according to claim 6, wherein the vinyl-lactam is vinylcaprolactam. 8. Product according to claim 6, wherein the molar ratio vinyl-lactam/ionic methacrylate is in the range 2/1 to 100/1. 9. Product according to claim 3, wherein the ionic methacrylate is a cationic methacrylate selected from of [2-(methacryloyloxy)alkyl]trimethylammonium salts, dimethylaminoethyl and diethylaminoethyl methacrylates. 10. Product according to claim 3, wherein the ionic methacrylate is a zwitterionic methacrylate selected from methacryloyloxyethyl phosphorylcholine or [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl) ammonium hydroxide methacrylate. 11. Product according to claim 3, wherein the ionic methacrylate is an anionic methacrylate selected from sulfoalkylmethacrylates salts. 12. Product according to claim 3, wherein the ionic methacrylate is a mixture of anionic methacrylate selected from sulfoalkyl methacrylates salts and cationic methacrylate selected from of [2-(methacryloyloxy)alkyl]trimethylammonium salts. 13. Product according to one of claims 3 to 12, wherein the crosslinkers are selected from ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, bisphenol A di(meth) acrylate, ethoxylate bisphenol A di(meth)acrylate, pentaerythritol tri-, and tetra(meth) acrylate, tetramethylene di(meth)acrylate, methylenebisacrylamide, methacryloxyethyl vinyl carbonate, triallylcyanurate, methacryloxyethyl vinyl urea, divinyl benzene, diallyl itaconate, allyl methacrylate, diallyl phthalate, polysiloxanylbisalkyl(meth)acrylate, polyethylene glycol di(meth)acrylate, vinyl methacrylate, divinyl adipate, divinylpyrrolidone derivatives, 1,3-divinylimidazolin-2-one or combinations thereof. 14. Product according to claim 13, wherein the crosslinkers are each present in concentrations in the range 0.1-10 moles% with respect to the moles of total monomers. 15. Product according to claim 13, wherein the crosslinkers are ethylene glycol di(meth)acrylate and 3,3 '-(propyl)-di-1-vinyl-2-pyrrolidone. 16. Product according to claim 1, comprising: a polymeric substrate that is nylon or polystyrene and b) a hydrogel based on vinylpyrrolidone, VP, or vinylcaprolactam monomers and two crosslinkers that are ethylene glycol dimethacrylate and 3,3'-(propyl)-di-1-vinyl-2-pyrrolidone, wherein there is an interface between the substrate and the hydrogel, an interface formed by a gradient of both the substrate and the hydrogel network -both forming a semi-interpenetrated network. 17. A product according to one of claims 1 to 16, which is structured on its surface. 18. A product according to claim 17, which is structured on its surface by the formation of wrinkles. 19. A process to obtain the product defined in any of claims 1 to 18, wherein the process comprises at least the following steps: a) mixing the hydrogel precursor monomers, the vinyl-lactam derivative, the ionic methacrylate, if present, and at least two crosslinkers with a photoinitiator, b) deposition of the mixture of (a) on the surface of the polymeric substrate and induction of photopolymerization under UV radiation and c) swelling of the product obtained in (b) by immersion in water or in ethanol. 20. A process according to claim 19, wherein the polymeric substrate is selected from polystyrene, methyl polymethacrylate, nylon, polycarbonate, polylactic acid or polycaprolactone. 21. A process according to claim 19, wherein the polymeric substrate is nylon or polycarbonate. 22. A process according to one of claims 19 to 21, wherein the vinyl-lactam is selected vinylcaprolactam or vinylpyrrolidone. 23. A process according to claim 19, wherein the vinyl-lactam is vinylcaprolactam.. 24. A process according to one of claims 19 to 23, wherein the ionic methacrylate is a cationic methacrylate selected from [2-(methacryloyloxy)alkyl]trimethylammonium salts. 25. A process according to claims 19 to 23, wherein the ionic methacrylate is a zwitterionic methacrylate selected from methacryloyloxyethyl phosphorylcholine or [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide methacrylate. 26. A process according to claims 19 to 23, wherein the ionic methacrylate is an anionic methacrylate selected from sulfoalkylmethacrylates salts. 27. A process according to claims 19 to 23, wherein the crosslinkers are selected from ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, bisphenol A di(meth)acrylate, ethoxylate bisphenol A di(meth)acrylate, pentaerythritol tri-, and tetra(meth)acrylate, tetramethylene di(meth)acrylate, methylenebisacrylamide, methacryloxyethyl vinyl carbonate, triallylcyanurate, methacryloxyethyl vinyl urea, divinyl benzene, diallyl itaconate, allyl methacrylate, diallyl phthalate, polysiloxanylbisalkyl(meth)acrylate, polyethylene glycol di(meth)acrylate, vinyl methacrylate, divinyl adipate, divinylpyrrolidone derivatives, 1,3-divinylimidazolin-2-one or combinations therof. 28. A process according to claim 27, wherein the crosslinkers are ethylene glycol di(meth)acrylate and 3,3'-(propyl)-di-1-vinyl-2-pyrrolidone. 29. A method according to any of claims 13 to 27, wherein the UV radiation is maintained between 10 and 60 minutes. 30. A process according to any of claims 19 to 28, wherein the crosslinkers are used in a percentage comprised between 0.1% and 20% in moles with respect to the total monomer content. 31. A process according to any one of claims 19 to 28, wherein the crosslinkers are each used in a percentage comprised between 0.1% and 10% in moles with respect to the total monomer content. 32. Use of the material defined in any of claims 1 to 18 to obtain materials for cell cultures. 33. Use of the material defined in any of claims 1 to 18, for the coating of 3D objects. 34. Use of the material defined in any of claims 1 to 18, for the manufacturing of thermosensitive mechanical actuators.