MX2012008558A - Nanocomposite hydrogel and method for preparing it, for industrial and medical applications. - Google Patents

Abstract

Nanocrystalline cellulose (NCC) is employed as the cross-linker and reinforcement domain for developing nanocomposite hydrogels possessing high strength and improved diffusion property; the resulting nanocomposite hydrogels are shown to have high mechanical properties, reversible swelling ability, and are biodegradable and biocompatible; the approach relies on free radical polymerization to form the hydrogels using a variety of hydrophilic vinyl monomers. These hydrogels are suitable for developing highly absorbent hygiene products, as well as for applications in medicine, engineering materials and sensors.

Description

HIDROGEL NANOCOMPUESTO AND METHOD TO PREPARE IT. FOR INDUSTRIAL AND MEDICAL APPLICATIONS TECHNICAL FIELD The invention relates in general to novel nanocomposite hydrogels, and to a method for preparing nanocomposite hydrogels, and more specifically to the application of nanocrystalline cellulose (NCC) as a crosslinking agent and also as a strengthening domain in polymeric hydrogels. The proposal is based on the polymerization by free radicals to form the hydrogels using a variety of hydrophilic vinyl monomers. This invention is suitable for developing applications in medicine, engineering materials, sensors and consumer products (e.g., highly absorbent hygiene products).

BACKGROUND OF THE INVENTION Polymeric hydrogels are networks of cross-linked hydrophilic polymers that swell when they absorb large amounts of water. Hydrogels have been extensively researched in the last decades for a wide variety of applications, such as drug delivery, tissue engineering, sensor that responds to stimuli, etc.1"6 In general, hydrogels are soft and fragile. , there are applications that they require significant mechanical loads, for example medical implants and some electrochemical devices.7 The design of hydrogels for a large number of new and existing applications requires that they possess sufficient mechanical strength, and also that they retain their original properties, such as the ability to respond to stimuli and rapid diffusion.

In nature, there are many hydrogels with very high mechanical resistances.7 Many marine plants, such as cochayuyo, are polysaccharide hydrogels reinforced with polymeric or inorganic fibers. In the human body, the cartilages, the corneas and the dermis are all hydrogels reinforced with fibers. These fibers reinforce the hydrogels acting as the charging components.

Recently, three new hydrogels with good mechanical properties have been reported: topological gels, nanocomposite gels and double network gels. Topological gels have figure-eight crosslinking agents that are capable of sliding along polymer chains.8 As a result, these gels are highly stretchable and can absorb large amounts of water. In nanocomposite gels, the polymer chains are crosslinked by nanoparticles, for example inorganic clay, instead of organic crosslinking agents.9 Nanocomposite hydrogels are also highly stretchable and have very good tensile strength. The double network hydrogels have two interpenetrating polymer networks: one is a highly crosslinked rigid polymer matrix, while the other is a flexible polymer matrix crosslinked in loose form.10 These double network hydrogels have a very high hardness and tenacity.

BRIEF DESCRIPTION OF THE INVENTION This invention seeks to provide a novel nanocomposite hydrogel.

This invention also seeks to provide a new method for preparing a nanocomposite hydrogel.

In one aspect of the invention, there is provided a nanocomposite hydrogel comprising a hydrophilic polymer crosslinked by a crosslinking agent comprising nanocrystalline cellulose (NCC).

In another aspect of the invention, there is provided a method for preparing a nanocomposite hydrogel comprising: polymerizing a hydrophilic monomer to form a hydrophilic polymer in the presence of a crosslinking agent for said polymer, comprising nanocrystalline cellulose (NCC).

In other aspects of the invention, novel devices are provided, for example medical devices and absorbent hygiene devices formed from the nanocomposite hydrogel of the invention.

In other aspects of the invention, the use of the nanocomposite hydrogel of the invention is provided as an engineering material.

In other aspects of the invention, the use of the nanocomposite hydrogel of the invention is provided as a delivery system for drugs in medical applications.

In other aspects of the invention, the use of the nanocomposite hydrogel of the invention is provided as a sensor responsive to stimuli.

In other aspects of the invention, the use of the nanocomposite hydrogel of the invention for medical implants is provided.

In other aspects of the invention, the use of the nanocomposite hydrogel of the invention in tissue engineering is provided.

DETAILED DESCRIPTION OF THE INVENTION The nanocomposite hydrogel comprises a hydrophilic polymer, in particular a hydrophilic polymer derived from the polymerization of a hydrophilic vinyl monomer, which polymer is crosslinked by a crosslinking agent comprising nanocrystalline cellulose (NCC).

Nanocrystalline cellulose (NCC) is extracted as a colloidal suspension by acid hydrolysis typically from chemical wood pulps, but other cellulosic materials such as bacteria, marine animals containing cellulose (eg tunicates) or cotton may be used. The NCC is made up of cellulose, a linear polymer of D-glucose units linked by β (4 4) bonds, whose chains are arranged to form crystalline and amorphous domains. The NCC obtained by extraction Hydrolytic has a degree of polymerisation (GP) in the range of 90 < GP = 1 10, and 3.7-6.7 sulfate groups per 100 anhydroglucose units. The NCC comprises crystallites whose physical dimension is in the range between 5-10 nm cross section and 20-100 nm in length, depending on the raw material used in the extraction. These charged crystallites can be suspended in water, or other solvents if they are properly derivatized, or they can self-assemble to form solid materials by air drying, spraying or freezing. Once dried, the NCC forms an agglomeration of structures of type parallelepiped rods, which have cross sections in the range of nanometers (5-20 nm), while their lengths are greater in orders of magnitude (100-1, 000 nm ), resulting in high relationships between dimensions. The NCC is also characterized by a high crystallinity (> 80%, and more likely between 85 and 97%) approaching the theoretical limit of the cellulose chains. The hydrogen bonds between the cellulose chains can stabilize the local structure in the NCC, and have a key role in the formation of crystalline domains. The crystallinity, defined as the crystalline fraction of the sample, strongly influences the physical and chemical behavior of the NCC. For example, the crystallinity of NCC has a direct influence on accessibility for chemical derivatization and swelling and water binding properties.

In particular, the crosslinking agent comprises a modified NCC in which one modifier has a first functional group coupled with a hydroxyl group of the NCC, and a second functional group coupled to the polymer.

The modifier is suitably a vinyl monomer having a functional group, by way of example glycidyl methacrylate may be mentioned. Based on their molecular structures, a group of chemical compounds can be appropriately selected to function as modifiers for NCC. Some examples are: trimethylsilyl methacrylate, 2- (trimethylsilyloxy) ethyl methacrylate, 2-aminoethyl methacrylate, 2-isocyanatoethyl methacrylate, 2-chloroethyl acrylate, 3- (trimethoxysilyl) propyl acrylate, glycidyl acrylate, isocyanate vinyl, 2-aminoethyl vinyl ether and vinyltrimethoxysilane.

Suitable hydrophilic monomers include, by way of example, acrylic acid, acrylamide (AM), vinyl-2-pyrrolidinone, N-isopropylacrylamide (NIPAM) and N-vinyl formamide (NVF). The following group of hydrophilic monomers can also be identified for the formation of polymers: α-ethylacrylic acid, methacrylic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid, allyl hydroxypolyethoxy ether (10), 2-hydroxyethyl acrylate, potassium salt of 3-sulfopropyl acrylate, poly (ethylene glycol) acrylate, tetrahydroxyethyl acrylate id rofurfu rilo and methacrylamide. Moreover, in principle all the monomers mentioned above can also be chosen as comonomers, for the hydrophilic polymer to be a hydrophilic copolymer, and therefore as suitable combinations for the copolymerization reaction. Combinations of suitable comonomers for the copolymerization to produce the hydrophilic polymer are, for example, acrylamide and acrylic acid, acrylamide and methacrylic acid, A / -isopropylacrylamide and acrylic acid, N-isopropylacrylamide and poly (ethylene glycol) acrylate, and poly (ethylene glycol) acrylate and acrylamide.

Thus, the polymerization of the hydrophilic vinyl monomer can be a homopolymerization of a vinyl monomer or a homopolymerization of a vinyl monomer and a comonomer.

In the case of a copolymerization, in order to prepare a good hydrogel, hydrophilic monomers and hydrophilic comonomers are used to form the crosslinked network which should be capable of swelling in aqueous media.

It should be understood that the first functional group can be any group that will react or be coupled with a group in the NCC such as a hydroxyl group, to couple the modifier to the NCC; and the second functional group can be any group that will react or mate with a group in the polymer or monomer that forms the polymer. Those skilled in the art will be able to select modifiers with suitable functional groups to couple with the NCC and the hydrophilic polymer or monomer to form this polymer. Similarly, persons skilled in the art will be able to select monomers for polymer formation that have suitable functional groups to couple with the second functional group of a modifier.

It should be understood that, although reference is made to a monomer for the formation of the polymer, it is within the invention further employing comonomers so as to produce crosslinked copolymers in place of crosslinked homopolymers; in such a case, comonomers do not need to participate in cross-linking even though this is also possible. In this way, hydrogels with a variety of desired characteristics can be produced by the selection of hydrophilic monomers, modifiers and optional comonomers.

In addition, a method is provided for the preparation of nanocomposite hydrogels with nanocrystalline cellulose (NCC) as the crosslinking agent and the strengthening domain. Each NCC nanoparticle joins at least two units of the modifier. It is expected that the NCC will be distributed completely randomly within the structure of the hydrogel. The prepared hydrogel has high mechanical strength but maintaining the original properties. Compared to clay-based nanocomposite hydrogels, NCC is biodegradable and biocompatible. This makes NCC-based hydrogels more promising for applications related to medicine, since biodegradability and biocompatibility are critical. The preparation of the nanocomposite hydrogel with NCC involves a two-step process. The first step is the modification of the NCC to make it a suitable crosslinking agent, and the second is the in situ polymerization of hydrophilic vinyl monomers with the NCC modified to prepare nanocomposite hydrogels.

The hydrogels of the invention possess excellent mechanical strength but retain their original properties, such as ability to respond to stimuli and rapid diffusion, and therefore can be developed to a large number of new applications based on hydrogels.

In specific embodiments of this invention, free radical polymerization is used to form nanocompound hydrogenates based on nanocrystalline cellulose (NCC). A variety of hydrophilic vinyl monomers are suitable, such as acrylic acid, acrylamide (AM), vinylpyrrolidone, N-isopropylacrylamide (NIPAM), N-vinylformamide (NVF), etc. Because there is no cross-linking point in the NCC during polymerization, the NCC must first be modified to function as a cross-linking agent. The modification is carried out following a procedure in which a vinyl monomer with functional groups, for example glycidyl methacrylate (GMA), is used to react with the hydroxyl groups in the NCC, resulting in NCC coupled with the methacrylate group. Next, the nanocomposite hydrogel is prepared using the modified NCC and hydrophilic monomers, such as acrylamide, and initiated with free radical initiators such as potassium persulfate. Following the process of this invention, the nanocomposite hydrogels prepared from the modified NCC are much more resistant than the hydrogels prepared from a normal organic crosslinking agent, for example? /,? / '- methylenebisacrylamide (BIS) .11 The ability to swell with the water of the resulting nanocomposite hydrogel is reversible, indicating that the diffusion property of the hydrogel is conserved while the mechanical properties are improved. The molecular weight or length of the polymer chain between the NCC particles can be controlled by two main factors: (i) the concentration of NCC, and (ii) the density of grafted modifiers on the surface of the NCC. The greater the concentration of NCC and the density of the grafted modifier on the surface of the NCC, the shorter the polymer chains will be. Conversely, the lower the concentration of NCC and the density of the grafted modifier on the surface of the NCC, the longer the polymer chains become. However, the concentration of NCC can also affect the mechanical strength of the resulting hydrogel.

The method described above is not limited to the use of acrylamide as the monomer. The choice of different monomers is dependent on the final application. For different monomer systems, nanocomposite hydrogels may be able to respond to pH, sensitive to temperature, electrochemically sensitive, etc. The increase in mechanical strength will expand the potential application of hydrogels to a wide range of engineering materials and medical systems.

A detailed description of the specific steps that can be employed for the preparation of nanocompound hydrogels based on NCC is disclosed below. 1. Modification of the surface of NCC with a vinyl monomer that has suitable functional groups: a suspension of NCC in water with a certain concentration, for example 4.38% by weight. The pH of the NCC suspension is adjusted to neutral, and then the NCC suspension is dried using an appropriate technique, for example spray-drying or freezing. Several grams of freeze-dried NCC, typically 1 to 10 g, for example 5 g, are resuspended in 50 to 500 ml of an appropriate solvent, for example dimethylsulfoxide (DMSO), preferably 100 ml, with stirring for 10 min and 4 hours until the NCC is totally suspended. The choice of solvent is limited only by the fact that the NCC suspension must be fully dispersed. Next, the suspension of NCC is ultrasonicated for 10 to 60 min. The desired amount of a catalyst, for example 1 g of 4-dimethylaminopyridine (DMAP), is added to the suspension, and then nitrogen is bubbled into the suspension for 10 to 60 min to remove the dissolved oxygen. The reaction is initiated by introducing into the suspension the required amount, for example 0.73 g, of a suitable vinyl monomer with functional groups, for example glycidyl methacrylate (GMA). The reaction can be carried out at any temperature in the range from room temperature to the degradation temperature of the NCC; in this case 50 ° C is used. The reaction time can be in the range from 4 hours to several days, and here 48 hours are used. The reaction time, temperature and the ratio of GMA to NCC will determine the degree of modification. After the reaction, some deionized water (DI), 100 ml in this case, is introduced into the suspension and the pH of the system is adjusted to 7-8. The suspension obtained is dialyzed against DI water for 3 to 10 days, 7 days in this case. After dialysis, the suspension is ultrasonicated for 30 min and filtered, for example, through Whatman filter paper No. 42. Finally, the pH of the modified NCC suspension is adjusted to 7-8 and freeze dried. 2. Preparation of nanocomposite hydrogels based on NCC: The calculated quantity of modified NCC and acrylamide are dissolved in DI water, stirring until fully dissolved, typically 10 min to 60 min, and then subjected to ultrasonication for 10 to 30 min. Then, the suspension is filtered through a 0.45 pm needle filter. The desired amount of a suitable catalyst, for example?,?,? ',?' - tetramethylethylenediamine (TEMED), is added to the NCC suspension to aid in the generation of free radicals from the initiator, and nitrogen is bubbled into the suspension for at least 30 min. The calculated amount of a suitable initiator, for example potassium persulfate (KPS), is dissolved in DI water and nitrogen is bubbled at the same time. To initiate the reaction, the KPS solution is introduced into the NCC suspension in an ice-water bath. The free-radical polymerization in situ is allowed to proceed at room temperature for 1 to 5 days, for example 2 days, until the reaction is completed under a nitrogen atmosphere. The molar ratio between the monomer (acrylamide), initiator (KPS) and catalyst (TEMED) is kept constant in this specific sample at 381: 1: 2.35. Different ratios of NCC to acrylamide can be used to optimize the effect of NCC concentration on the mechanical properties of the nanocomposite hydrogel. The Molar ratio of other reactants can also be adjusted within a reasonable range to control the properties of hydrogels with prepared NCC.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1: is a diagram of how NCC functions as a crosslinking agent in the described nanocomposite hydrogels. Each nanoparticle joins at least two units of the modifier. The NCC is expected to be distributed completely randomly within the structure of the hydrogel; Figure 2: is a modified FT-IR spectrum of NCC according to the conditions described in Table 1; Figure 3: is a graph showing the tensile behavior of the nanocomposite based on NCC (open triangles) and hydrogels based on BIS (solid line); Figure 4: is a graph showing the tensile strength response to an increase in the charge of the nanocompensation / crosslinking agent for the NCC-based nanocomposite (solid triangle) and the BIS-based hydrogels (solid square); Y Figure 5: is a graph showing the compression modulus as a function of the charge of the nanocompensation / crosslinking agent for the nanocomposite based on NCC (solid triangle) and the hydrogels based on BIS (solid square).

BOARDS TABLE 1 Size and surface charge of modified NCC prepared using the indicated conditions TABLE 2 Reasons for swelling of nanocomposite based on NCC and hydrogels based on BIS EXAMPLE 1 The modification of NCC by GMA is controlled using different reaction conditions. It is illustrated in Table 1 that the surface charge of the modified NCC is decreased compared to the original NCC. Moreover, the modified NCC becomes smaller in size than the original NCC. This is probably because the catalyst, DMAP, is a base, which will possibly hydrolyze the NCC to make it smaller and decrease the surface charge. To confirm the GMA graft on NCC, an infra-red test with Fourier transform (FT-IR) is performed to verify the modified NCC samples. As shown in Figure 2, the peak at about 1720 cm "1 represents the vibration of the carbonyl group in the methacrylate, indicating that the methacrylate group is grafted onto the NCC.

EXAMPLE 2 The mechanical properties of the hydrogels can be analyzed using an Instron tensile testing machine, or any other, at an extension rate of 100 mm / min. The gauge length was set at 30 mm, and the test specimen was a solid cylinder with a diameter of 1.46 mm. The initial cross section is used to calculate the tensile strength and modulus.

Figure 3 exhibits typical tensile responses of (1) nanocomposite hydrogel based on NCC prepared according to this invention, and (2) hydrogel prepared using an organic crosslinking agent, BIS. The nanocomposite hydrogel based on NCC exhibits a behavior characteristically different from that of hydrogels produced using organic crosslinking agents. The nanocomposite hydrogel based on NCC shows a clear inflection point at around 100% deformation, indicating the transition from elastic to plastic linear response. This elastic-plastic behavior indicates that nanocomposite hydrogels based on NCC (1) have the capacity to absorb a significant amount of energy (highly tenacious material), (2) are rigid (high modulus) and (3) have high resistance to traction in the plastic range (more than 7 times higher than in the elastic range). This significant plastic response for nanocomposite hydrogels based on NCC is a unique feature made possible by the NCC's reinforcement mechanism.

Figure 4 illustrates the tensile strength response as a function of increasing contents of NCC (or BIS) in nanocompound hydrogenates based on NCC, and hydrogels prepared using an organic crosslinking agent, respectively. It is evident that the tensile strength increases with increasing BIS content (solid squares), reaches a peak at -0.015 MPa, and then decreases. However, the tensile strength for the nanocomposite hydrogel based on NCC increases steadily with increasing NCC content (solid triangles). For example, at 50% w / w of NCC charge on the monomer, the tensile strength reaches 0.126 MPa, more than 8 times higher than for the normal hydrogel.

EXAMPLE 3 Compression tests are performed using a mechanical thermal analyzer (TMA Q 400) under an expansion probe. The height of the sample is around 6 mm and the diameter of the probe is 2795 mm. The measurement is carried out applying an initial force of 0.01 N and a force ramp of 0.1 N / min up to 1.2 N. Compressions between 0.5 and 2.5 mm are used to calculate the compression module.

Figure 5 illustrates the compression modulus of the hydrogels as a function of the crosslinking or loading densities of NCC as a percentage by weight on the monomer. For example, for the hydrogel with BIS (solid squares), the compression modulus increases with increasing concentration of the crosslinking agent and the data follows a logarithmic response that stabilizes at ~ 9 kPa. However, the compression module for the nanocomposite hydrogel based on NCC increases exponentially by increasing the charge of NCC (solid triangles). The results also indicate that the increase of the modified NCC charge in the nanocomposite hydrogel will increase the compression modulus at a much faster rate than in the case of BIS-based hydrogels.

EXAMPLE 4 The swelling properties of the hydrogels are measured by soaking the hydrogels prepared in DI water for 3 days, and comparing the weights of the hydrogels before and after swelling. The swelling ratio is defined as the ratio between the weight after soaking and the weight before soaking. Table 2 clearly shows that nanocomposite hydrogels with NCC have higher swelling ratios than normal hydrogels. It was also found that the swelling of NCC-based nanocomposite hydrogels is reversible if they are dried and re-soaked in water.

References: 1. Yoshida, R., Design of functional polymer gels and their application to biomimetic materials. Current Organic Chemistry 2005, 9, (16), 1617-1641. 2. Tokarev, I. Minko, S., Stimuli-responsive hydrogel thin films. Soñ Matter 2009, 5, (3), 51 1-524. 3. Peppas, N. A .; Hilt, J. Z .; Khademhosseini, A .; Langer, R., Hydrogels in biology and medicine: From molecular principies to bionanotechnology. Advanced Materials 2006, 18, (11), 1345-1360. 4. Hoare, T. R .; Kohane, D. S., Hydrogels in drug delivery: Progress and challenges. Polymer 2008, 49, (8), 1993-2007. 5. Richter, A .; Paschew, G .; Klatt, S .; Lienig, J .; Arndt, K. F .; Adler, H.JP., Review on hydrogel-based pH sensors and microsensors. Sensors 2008, 8, (1), 561 -581. 6. He, C. L; Kim, S. W .; Lee, D. S., In situ gelling stimuli-sensitive block copolymer hydrogels for drug delivery. Journal of Controlled Relay 2008, 127, (3), 189-207. 7. Calvert, P., Hydrogels for Soft Machines. Advanced Materials 2009, 21, (7), 743-756. 8. Okumura, Y .; Ito, K., The polyrotaxane gel: A topological gel by figure-of-eight cross-links. Advanced Materials 2001, 13, (7), 485- +. 9. Haraguchi, K., Nanocomposite hydrogels. Current Opinion in Solid State & Materials Science 2007, 11, (3-4), 47-54. 10. Gong, J. P. Katsuyama, Y .; Kurokawa, T .; Osada, Y., Double-network hydrogels with extremely high mechanical strength. Advanced Materials 2003, 15, (14), 1155- +. 11. Haraguchi, K .; Takehisa, T .; Fan, S., Effects of clay contained on the properties of nanocomposite hydrogels composed of poly (N-isopropylacrylamide) and clay. Macromolecules 2002, 35, (27), 10162-10171.

Claims (20)

NOVELTY OF THE INVENTION CLAIMS

1. A nanocomposite hydrogel, characterized in that it comprises a hydrophilic polymer crosslinked by a crosslinking agent comprising nanocrystalline cellulose (NCC), wherein said crosslinking agent comprises a modified NCC in which a modifier has a first functional group coupled with a hydroxyl group of the NCC, and a second functional group coupled to said polymer.

2. The nanocomposite hydrogel according to claim 1, further characterized in that said hydrophilic polymer is derived from the polymerization of a hydrophilic vinyl monomer.

3. The nanocomposite hydrogel according to claim 1, further characterized in that said hydrophilic polymer is derived from the copolymerization of a hydrophilic vinyl monomer and a comonomer for said hydrophilic vinyl monomer.

4. The nanocomposite hydrogel according to claim 3, further characterized in that said comonomer is a hydrophilic comonomer.

5. The nanocomposite hydrogel according to claim 1, further characterized in that said hydrophilic polymer is derived from the polymerization of a hydrophilic monomer selected from acrylic acid, acrylamide (AM) and vinylpyrrolidone, N-isopropylacrylamide (NIPAM), and N-vinylformamide (NVF) ).

6. The nanocomposite hydrogel according to any of claims 1 to 5, further characterized in that said modifier is a vinyl monomer having a functional group.

7. The nanocomposite hydrogel according to any of claims 1 to 5, further characterized in that said modifier is selected from the group consisting of glycidyl methacrylate, trimethylsilyl methacrylate, 2- (trimethylsilyloxy) ethyl methacrylate, 2-aminoethyl methacrylate, methacrylate 2-isocyanatoethyl, 2-chloroethyl acrylate, 3- (trimethoxysilyl) propyl acrylate, glycidyl acrylate, vinyl isocyanate, 2-aminoethyl vinyl ether and vinyltrimethoxysilane.

8. The nanocomposite hydrogel according to claim 6, further characterized in that said vinyl monomer having a functional group is glycidyl methacrylate.

9. A method for preparing a nanocomposite hydrogel, comprising: polymerizing a hydrophilic monomer to form a hydrophilic polymer in the presence of a crosslinking agent for said polymer, comprising nanocrystalline cellulose (NCC).

10. The method according to claim 9, further characterized in that said hydrophilic monomer is a hydrophilic vinyl monomer.

1 1. The method according to claim 9 or 10, further characterized in that said polymerization comprises the copolymerization of said hydophilic monomer and a comonomer.

12. The method according to claim 1, further characterized in that said comonomer is a hydrophilic comonomer.

13. The method according to any of claims 9 to 12, further characterized in that said crosslinking agent comprises modified NCC with a modifier having first and second functional groups, said first functional group reacting with a hydroxyl group of the NCC, and coupling said second functional group to the polymer.

14. The method according to any of claims 9 to 13, further characterized in that said hydrophilic monomer is selected from acrylic acid, acrylamide (AM) and vinylpyrrolidone, N-isopropylacrylamide (NIPAM), and N-vinylformamide (NVF).

15. The method according to claim 13, further characterized in that said modifier is selected from the group consisting of glycidyl methacrylate, trimethylsilyl methacrylate, 2- (trimethylsilyloxy) ethyl methacrylate, 2-aminoethyl methacrylate, 2-isocyanatoethyl methacrylate, acrylate. of 2-chloroethyl, 3- (trimethoxysilyl) propyl acrylate, glycidyl acrylate, vinyl isocyanate, 2-aminoethyl vinyl ether and vinyltrimethoxysilane.

16. The method according to claim 13, further characterized in that said modifier is a vinyl monomer having a functional group.

17. The method according to claim 16, further characterized in that said vinyl monomer having a functional group is glycidyl methacrylate.

18. A medical device formed of the nanocomposite hydrogel of any of claims 1 to 8.

19. An absorbent hygiene device formed of the nanocomposite hydrogel of any of claims 1 to 8.

20. The medical device in accordance with the claim 18, further characterized in that it is selected from a drug delivery system for medical applications; a sensor that responds to stimuli, a medical implant and a tissue engineering material.