Graft polymer, composition, curable material, and cured product

Abstract

This graft polymer is obtained by grafting a polymer of an acrylic monomer to a biocompatible polymer.

Description

Graft polymers, compositions, curable materials, and cured products

[0001] This disclosure relates to graft polymers, compositions, curable materials, and cured products used for bone strengthening and the like.

[0002] A technique for strengthening human bones by injecting biomaterials into them is known. For example, Patent Document 1 discloses a bone cement composition kit comprising a first component containing a polymerization initiator and a second component containing a methacrylate monomer.

[0003] International Publication No. 2013 / 129292

[0004] This disclosure provides graft polymers and the like that are useful for adjusting the properties of materials that increase bone strength.

[0005] A graft polymer according to one aspect of this disclosure is a graft polymer in which a polymer of an acrylic monomer is grafted onto a biocompatible polymer.

[0006] A composition according to one aspect of the present disclosure comprises the above-mentioned graft polymer and an acrylic monomer, wherein the graft polymer is dissolved in the acrylic monomer.

[0007] A curable material according to one aspect of the present disclosure comprises the above composition and a polymerization initiator.

[0008] A cured product according to one aspect of this disclosure is a cured product obtained by curing the above-mentioned curable material.

[0009] According to this disclosure, it is possible to provide graft polymers and the like that are useful for adjusting the properties of materials that increase bone strength.

[0010] Figure 1 is a diagram illustrating an example of a usage scenario for the biomaterial according to the embodiment. Figure 2 is a flowchart showing an example of a method for producing a graft polymer according to the embodiment. Figure 3 is a diagram showing an overview of the synthesis of the graft polymer according to the example. Figure 4 is a diagram showing the synthesis flow of PGA-AIP. Figure 5 is a diagram showing the IR spectrum of PGA-AIP obtained in the example. Figure 6 is a diagram showing the IR spectrum of PGA-AIP obtained in the example. １Figure 7 shows the HNMR spectrum. Figure 8 shows the IR spectrum of PGA-PMMA obtained in Example 1. Figure 9 shows the IR spectrum of PGA-PMMA obtained in Example 1. １ This figure shows the HNMR spectrum. Figure 10 shows the PGA-PMMA obtained in Example 1. １ This figure shows the integral values ​​in the HNMR spectrum.

[0011] (Background to obtaining one aspect of this disclosure) The inventors of this application found that the following problems arise in the technology of injecting biomaterials into the bone, as described in the "Background Art" section.

[0012] As a biomaterial to be injected into the bone, curable materials containing acrylic monomers are known. Because curable materials containing acrylic monomers are stable in the human body over the long term, they are widely used as bone cement and the like, as disclosed in Patent Document 1.

[0013] Acrylic monomers change from liquid to solid through polymerization, but they are low-viscosity liquids before the polymerization reaction begins. Therefore, when acrylic monomers are injected into human bone alone, it is difficult to keep them in a specific location, and there is a risk of leakage of the acrylic monomers into the blood vessels. Furthermore, if bone strength is reduced due to osteoporosis or other causes, if the hardened acrylic monomer is too hard, the hardened material may cause bone damage.

[0014] Thus, when using curable materials containing acrylic monomers to increase bone strength, it is necessary to adjust the properties to make them more suitable for injection into bone.

[0015] Therefore, this disclosure provides graft polymers and the like that are useful for adjusting the properties of materials that increase bone strength.

[0016] The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0017] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, steps, and the order of steps shown in the following embodiments are examples only and are not intended to limit the disclosure. The various embodiments described herein can be combined with each other as long as they do not conflict. Furthermore, among the components in the following embodiments, those components that are not described in an independent claim are described as optional components.

[0018] Furthermore, in this specification, numerical ranges do not represent only strict meanings, but also include substantially equivalent ranges, such as differences of a few percent.

[0019] (Embodiment) The following describes the graft polymer according to this embodiment, the composition using the graft polymer, the biomaterial using the composition, and the cured product obtained by curing the biomaterial.

[0020] Figure 1 is a schematic cross-sectional view illustrating an example of a usage scenario for the biomaterial 10 according to this embodiment.

[0021] As shown in Figure 1, the biomaterial 10 according to this embodiment is injected, for example, into the femur 40. In this embodiment, the biomaterial 10 is an example of a hardening material, and the femur 40 is an example of bone.

[0022] The biomaterial 10 is used to increase the strength of the femur 40. Patients who fracture their femur 40 due to osteoporosis or other reasons are prone to difficulty walking. Furthermore, it is said that patients who have experienced a fracture of one of the two femurs 40 have a relatively high risk of fracturing the other (contralateral) femur 40 (contralateral fracture). Patients who have experienced a contralateral fracture will find walking even more difficult, or may become unable to walk at all. Therefore, by increasing the strength of the contralateral femur 40 by injecting the biomaterial 10 into patients who have experienced a femur 40 fracture (initial fracture), it is possible to prevent a fracture of the contralateral femur 40.

[0023] The biomaterial 10 comprises a composition containing a graft polymer and an acrylic monomer, and a polymerization initiator. For example, the composition and the polymerization initiator are prepared, and the biomaterial 10, which is a mixture of the prepared composition and the polymerization initiator, is injected into the femur 40. The mixing of the prepared composition and the polymerization initiator may be performed by an injection device, or the biomaterial 10, which is a mixture of the prepared composition and the polymerization initiator, may be injected into the femur 40 by an injection device. The strength of the femur 40 can be increased by fixing the hardened biomaterial 10 inside the femur 40.

[0024] The following describes in detail the graft polymer, composition, biomaterial 10, and cured product according to this embodiment.

[0025] [Graft Polymer] First, the graft polymer used in the biomaterial 10 according to this embodiment will be described. The graft polymer according to this embodiment is a graft polymer in which an acrylic monomer polymer is grafted onto a biocompatible polymer. In other words, in the graft polymer according to this embodiment, an acrylic monomer polymer is introduced into the side chain of the biocompatible polymer. As a result, when the graft polymer is used in the above composition, the graft polymer can be dissolved in the acrylic monomer and the viscosity of the composition can be effectively increased. Furthermore, because the main chain of the graft polymer is a biocompatible polymer, adverse effects on the human body can be suppressed even when the graft polymer is used in the biomaterial 10. Therefore, the graft polymer according to this embodiment is useful for adjusting the properties of the biomaterial 10 to increase bone strength.

[0026] As used herein, a biocompatible polymer refers to a polymer that has affinity with biological tissues and biological organs and has the property of not causing foreign body reactions, rejection reactions and the like when applied to a living body. The biocompatible polymer according to the present embodiment is, for example, a polymer derived from a natural product that can be extracted from natural products. Examples of polymers derived from natural products include alginic acid, collagen, gelatin, hyaluronic acid, dextran, chitosan, fibrin, γ-polyglutamic acid and silk fibroin. Hereinafter, "γ-polyglutamic acid" may be simply referred to as "polyglutamic acid". In other words, as used herein, the description of "polyglutamic acid" means "γ-polyglutamic acid". The biocompatible polymer may also be a chemically synthesized polymer such as polylactic acid, polyglycolide, polycaprolactone, polyethylene glycol, polyurethane, polyvinyl alcohol, polytrimethylene carbonate or polyethylene oxide, or may be a polymer derived from a microorganism synthesized by a microorganism such as polyhydroxybutyrate or polylysine.

[0027] From the viewpoint of facilitating grafting of a polymer of an acrylic monomer, the biocompatible polymer may have a carboxyl group in a side chain thereof. This allows molecules containing a functional group that reacts with a carboxyl group to be used for grafting. Examples of the biocompatible polymer having a carboxyl group in a side chain thereof include alginic acid, hyaluronic acid and polyglutamic acid. In addition, from the viewpoints of impact on the human body and ease of handling, the biocompatible polymer may be polyglutamic acid.

[0028] In addition, from the viewpoint of effectively increasing the viscosity of the composition, the biocompatible polymer may be a gelable polymer.

[0029] An acrylic monomer is an acrylic acid ester or a compound in which the hydrogen at the α-position of an acrylic acid ester such as methacrylic acid ester is substituted with a substituent.

[0030] The acrylic monomer used in the graft polymer according to the present embodiment is, for example, a methacrylic acid ester. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate and butyl methacrylate. Methacrylic acid esters have a high polymerization rate, can easily lengthen graft chains, and tend to easily increase the solubility of the graft polymer in acrylic monomers. From the viewpoints of polymerization and availability, the methacrylic acid ester may be methyl methacrylate.

[0031] In addition, from the viewpoint of ease of synthesis, the graft polymer according to the present embodiment may be a graft polymer represented by the following structural formula (1).

[0032]

[0033] In the graft polymer represented by structural formula (1), the biocompatible polymer is polyglutamic acid, and the acrylic monomer is methyl methacrylate. In addition, a polymer of methyl methacrylate is bound to the side chain of polyglutamic acid via an imidazoline ring structure and a dimethylmethylene group. In structural formula (1), the ratio of m to n (m / n) is, for example, 5 or more and 15 or less.

[0034] Here, an example of a method for producing the graft polymer according to the present embodiment will be described. FIG. 2 is a flowchart showing an example of the method for producing the graft polymer according to the present embodiment. The production method described below is an example, and the method for producing the graft polymer is not limited to the following method.

[0035] As shown in FIG. 2, in the production of the graft polymer according to the present embodiment, first, an azo group is introduced into the side chain of the biocompatible polymer (step S11). An azo group can be introduced into the side chain of the biocompatible polymer by reacting the biocompatible polymer with an azo compound having a functional group reactive with the functional group on the side chain of the biocompatible polymer. Various organic synthesis techniques can be used for introducing the azo group. The biocompatible polymer can easily introduce an azo group, for example, by including a carboxyl group, a hydroxyl group, or an amine in its side chain.

[0036] For example, in the case of biocompatible polymers having carboxyl groups in their side chains, such as the graft polymer shown in structural formula (1), azo groups can be easily introduced into the side chains of the biocompatible polymer by reacting them with an azo compound containing an amine structure. A specific example of an azo compound containing an amine structure is 2,2'-azobis[2-(2-imidazoline-2-yl)propane].

[0037] By introducing azo groups into the side chains of biocompatible polymers, it becomes possible to generate carbon radicals in the side chains of the biocompatible polymer that initiate the polymerization of acrylic monomers. Furthermore, although azo groups decompose with heat or light, the decomposition reaction is milder compared to peroxides, making compounds with introduced azo groups easier to handle.

[0038] Next, an acrylic monomer is graft polymerized onto the biocompatible polymer into which the azo group has been introduced (step S12). For example, by mixing the acrylic monomer and the biocompatible polymer into which the azo group has been introduced in a solvent and heating it, the azo group decomposes to generate carbon radicals, and a reaction occurs between the carbon radicals and the acrylic monomer, followed by polymerization of the acrylic monomer. As a result, a polymer of the acrylic monomer is grafted onto the biocompatible polymer.

[0039] [Composition] Next, the composition used in the biomaterial 10 according to this embodiment will be described. The composition according to this embodiment includes the above-mentioned graft polymer and an acrylic monomer. In the composition, the graft polymer is dissolved in the acrylic monomer. In the composition, the dissolution of the above-mentioned graft polymer in the acrylic monomer increases the viscosity of the composition compared to the state of the acrylic monomer alone. Therefore, when the composition is used in the biomaterial 10, the biomaterial 10 is more likely to remain in the femur 40, and leakage of the biomaterial 10 into the blood vessels can be suppressed. Thus, the graft polymer according to this embodiment is useful for adjusting the properties of the biomaterial 10 that increase bone strength.

[0040] When used as a biomaterial 10 to be injected into the bone, the viscosity of the composition at the time of injection is, for example, 1 Pa·s or more and 100 Pa·s or less, preferably 1 Pa·s or more and 30 Pa·s or less, and more preferably 1 Pa·s or more and 10 Pa·s or less. In this specification, the viscosity of the composition is a value obtained by measuring it using a rotational viscometer at room temperature (25°C).

[0041] The acrylic monomer included in the composition is, for example, a methacrylic acid ester. Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, and butyl methacrylate. The acrylic monomer included in the composition may be the same as the acrylic monomer used in the graft polymer described above.

[0042] In the composition, the ratio of graft polymer to acrylic monomer is, for example, 1 wt% to 10 wt%. From the viewpoint of making the biomaterial 10 using the composition suitable by increasing bone strength, the ratio of graft polymer to acrylic monomer may be 1.5 wt% to 4.5 wt%.

[0043] The composition may contain components other than the graft polymer and acrylic monomer. Various inorganic and organic additives can be used as components other than the graft polymer and acrylic monomer. Examples of inorganic additives include calcium phosphate, silicon dioxide, aluminum oxide, barium sulfate, and zirconium oxide. Examples of organic additives include polymers of acrylic monomers, copolymers of acrylic monomers, cellulose derivatives such as acetylcellulose, and acrylic rubber. Since the components other than the graft polymer and acrylic monomer are components that do not need to be included in the biomaterial 10, they may also be included in the liquid formulation containing the polymerization initiator used in the production of the biomaterial 10, as described below.

[0044] [Biomaterial and Cured Product] Next, the biomaterial 10 and the cured product obtained by curing the biomaterial 10 according to this embodiment will be described. The biomaterial 10 comprises the above composition and a polymerization initiator. The biomaterial 10 is manufactured, for example, by mixing the above composition and a liquid containing a polymerization initiator. The biomaterial 10 may also be manufactured by directly adding the polymerization initiator to the above composition. The biomaterial 10 hardens by polymerization of acrylic monomers and becomes a cured product, which is fixed inside the femur 40. This makes it possible to increase the strength of the femur 40.

[0045] For polymerization initiators, known polymerization initiators for acrylic monomers are used. Examples of polymerization initiators include benzoyl peroxide, tert-butyl peroxide, lauroyl peroxide, and azobisisobutyronitrile. The biomaterial 10 may further contain polymerization accelerators such as N,N-dimethyl-p-toluidine and tridimethylaminomethylphenol along with the polymerization initiator. N,N-dimethyl-p-toluidine and tridimethylaminomethylphenol may also be used as polymerization initiators.

[0046] Since the biomaterial 10 contains the above-described composition, as mentioned above, its viscosity before the polymerization reaction begins can be increased, and leakage of the biomaterial 10 into blood vessels can be suppressed. Furthermore, because the composition contains a graft polymer, when the composition is used in the biomaterial 10, the glass transition temperature of the acrylic polymer in the cured biomaterial 10 can be lowered, so that the elastic modulus can be lowered and the toughness can be increased in the cured biomaterial 10. As a result, damage to the femur 40 caused by the hardness and brittleness of the cured product can be suppressed. Thus, the graft polymer according to this embodiment is useful for adjusting the properties of the biomaterial 10 to increase bone strength.

[0047] The flexural modulus of a cured product obtained by curing the biomaterial 10 is, for example, 300 MPa or more and 10000 MPa or less, preferably 400 MPa or more and 8000 MPa or less, more preferably 500 MPa or more and 5000 MPa or less, and still more preferably 500 MPa or more and 2000 MPa or less. In the present specification, the flexural modulus of the cured product is a value obtained by measurement at room temperature (25°C) using an ordinary method in which both ends of a measurement object are fixed and a load is applied from the upper center of the object. When the acrylic monomer contained in the composition is methyl methacrylate, the flexural modulus of a cured product obtained by curing the biomaterial 10 is, for example, 500 MPa or more and 2000 MPa or less.

[0048] The toughness of a cured product obtained by curing the biomaterial 10 is, for example, 0.1 MJ / m ３ or more and 10 MJ / m ３ or less, preferably 0.2 MJ / m ３ or more and 8 MJ / m ３ or less, more preferably 0.3 MJ / m ３ or more and 5 MJ / m ３ or less, and still more preferably 0.8 MJ / m ３ or more and 5 MJ / m ３ or less. In the present specification, the toughness of the cured product is a value calculated from the area of a stress-strain curve obtained by measurement at room temperature (25°C) using an ordinary bending tester that performs measurement by fixing both ends of a measurement object and applying a load from the upper center of the object. When the acrylic monomer contained in the composition is methyl methacrylate, the toughness of a cured product obtained by curing the biomaterial 10 is, for example, 0.8 MJ / m ３ or more and 5 MJ / m ３ or less.

[0049] (Examples) Hereinafter, the graft polymer and the composition according to the present disclosure are specifically described with reference to examples, but the present disclosure is not limited to the following examples in any way.

[0050] [Synthesis of Graft Polymer] The graft polymer according to the example was synthesized by the following method.

[0051] Figure 3 shows an overview of the synthesis of the graft polymer according to the example. In the example, PGA-PMMA, shown in Figure 3, was synthesized, which is a graft polymer in which a polymer of methyl methacrylate (PMMA) is grafted onto polyglutamic acid (γ-PGA). In the synthesis of the graft polymer (PGA-PMMA), first, PGA-AIP, shown in Figure 3, was synthesized by introducing 2,2'-azobis[2-(2-imidazolin-2-yl)propane] (AIP), which contains an azo group, into polyglutamic acid (γ-PGA). Next, PGA-PMMA was synthesized by reacting PGA-AIP with methyl methacrylate (MMA).

[0052] The raw materials used in the synthesis were as follows, and were used as is without any purification or other processing.

[0053] - Polyglutamic acid (γ-PGA, acid form): Manufactured by VEDAN Enterprise Corporation, molecular weight 460 (expressed in kDa) - 2,2'-Azobis[2-(2-imidazolin-2-yl)propane] (AIP): Manufactured by Fujifilm Wako Pure Chemical Industries - N,N'-Dicyclohexylcarbodiimide (DCC): Manufactured by Tokyo Chemical Industries - Methyl methacrylate (MMA): Manufactured by Nacalai Tesque

[0054] The following describes the details of the synthesis of PGA-AIP and PGA-PMMA.

[0055] (1) Synthesis of PGA-AIP Figure 4 shows the synthesis flow of PGA-AIP. As shown in Figure 4, in the synthesis of PGA-AIP, first, 20 mmol of polyglutamic acid in acid form (PGA acid form) was added to 20 mL of dimethyl sulfoxide (DMSO) and stirred at 70°C for 2 hours to dissolve it. After cooling the PGA solution to room temperature (RT), 1 mmol of AIP dissolved in 5 mL of DMSO and 2 mmol of DCC dissolved in 5 mL of DMSO were added and stirred at 25°C for 5 hours to react with γ-PGA. Then, the reaction solution was centrifuged for 13 minutes to remove the precipitate, and 1000 mL of acetone was added to reprecipitate it. The precipitate was obtained by suction filtration, and then PGA-AIP was obtained by vacuum drying at 25°C for 5 hours.

[0056] The obtained PGA-AIP was subjected to Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy. １ The analysis was performed using HNMR. １ In HNMR, PGA-AIP is converted to deuterated DMSO (DMSO-d ６ The measurement was taken after dissolving it in (). Figure 5 is a diagram showing the IR (infrared) spectrum of PGA-AIP obtained in the example. In Figure 5, in addition to the IR spectrum of PGA-AIP, the IR spectra of PGA and AIP are also shown. In Figure 5, the horizontal axis is wavenumber and the vertical axis is absorbance. Figure 6 is the IR spectrum of PGA-AIP obtained in the example. １ This figure shows the HNMR spectrum. In Figure 6, the PGA-AIP １ In addition to HNMR spectra, PGA and AIP １ The 1H NMR spectrum is also shown. In Figure 6, the horizontal axis represents the chemical shift value, and the vertical axis represents the relative intensity.

[0057] As shown in Figure 5, the IR spectrum of PGA-AIP contains peaks for the N-H stretching vibration of the amine derived from AIP and peaks for the C=O stretching vibration of the amide derived from PGA.

[0058] Furthermore, as shown in Figure 6, PGA-AIP １ In the HNMR spectrum, there are peaks similar to the proton peaks of PGA shown in a, b, and c, and a proton peak shown in d2 that corresponds to the proton peak of AIP shown in d1.

[0059] From the above, it can be seen that PGA-AIP is obtained by the method described above.

[0060] (2) Synthesis of PGA-PMMA Figure 7 shows the synthesis flow of PGA-PMMA. As shown in Figure 7, in the synthesis of PGA-PMMA, first, 0.60 g of PGA-AIP was added to 25 mL of super-dehydrated DMSO and stirred at 70°C until dissolved. After the solution of PGA-AIP was cooled to 25°C, 10 mL (Examples 1 and 3) or 7.5 mL (Example 2) of MMA was added. Then, nitrogen (N) ２ After stirring for 10 minutes under nitrogen, the mixture was frozen and degassed once. For the freeze-degassing, the reaction mixture was first frozen for 30 minutes using liquid nitrogen and chloroform, then vacuumed and allowed to return to 25°C for 20 minutes to melt the reaction mixture. After freeze-degassing, the reaction mixture was stirred at 70°C for 21 hours under nitrogen to react PGA-AIP with MMA.

[0061] After the reaction, 30 mL of chloroform was added to the reaction solution and stirred, and then 3000 mL of methanol was added to reprecipitate. The resulting precipitate was obtained by suction filtration and then dried under reduced pressure at 25°C for 6 hours to obtain white powdered PGA-PMMA.

[0062] The obtained PGA-PMMA was subjected to FTIR and １ Analysis was performed using HNMR. １ In HNMR, PGA-PMMA is converted to deuterated DMSO (DMSO-d ６The IR spectrum was measured after dissolving it in ( ). Figure 8 shows the IR spectrum of PGA-PMMA obtained in Example 1. In addition to the IR spectrum of PGA-PMMA, Figure 8 also shows the IR spectra of PGA-AIP, PGA, and AIP. In Figure 8, the horizontal axis is wavenumber and the vertical axis is absorbance. Figure 9 shows the IR spectrum of PGA-PMMA obtained in Example 1. １ This figure shows the HNMR spectrum. In Figure 9, the PGA-PMMA spectrum is shown. １ In addition to HNMR spectra, PGA, MMA, and AIP １ The HNMR spectrum is also shown. In Figure 9, the horizontal axis represents the chemical shift value and the vertical axis represents the relative intensity. Figure 10 shows the PGA-PMMA obtained in Example 1. １ This figure shows the integral values ​​in the HNMR spectrum.

[0063] As shown in Figure 8, the IR spectrum of PGA-PMMA shows peaks for the C-H stretching vibration of the methyl group (a) in the PMMA portion, and peaks for the C=O stretching vibration and C-O stretching vibration of the ester (b) in the PMMA portion. Furthermore, the IR spectrum of PGA-PMMA does not show a peak at the position corresponding to the peak for the N-H stretching vibration of the secondary amine (c) in PGA-AIP.

[0064] Furthermore, as shown in Figure 9, PGA-PMMA １ In the HNMR spectrum, there is a proton peak indicated by a2 that corresponds to the proton peak of PGA indicated by a1, and a proton peak indicated by b2 that corresponds to the proton peak of MMA indicated by b1. Therefore, it can be seen that MMA and PGA are reacting. Furthermore, the PGA-PMMA reaction １ In the HNMR spectrum, there is no peak indicating a proton bonded to the double bond carbon in MMA, represented by c. Therefore, it can be concluded that MMA has polymerized to PMMA.

[0065] From the above, it can be seen that PGA-PMMA is obtained by the method described above.

[0066] Furthermore, when 3 wt% PGA-PMMA was added to MMA, the PGA-PMMA completely dissolved in the MMA. Since PGA alone does not dissolve in MMA, this indicates that PGA-PMMA was obtained.

[0067] Furthermore, as shown in Figure 10, PGA-PMMA １ In the HNMR spectrum, the ratio of the integral value of the proton peak indicated by a2 to the integral value of the proton peak indicated by b2 is 0.74:23.36. Therefore, the ratio of n to m (n:m) in the obtained PGA-PMMA is 0.74:23.36 / 3 = 1:10.07.

[0068] [Characteristics of Compositions Using Graft Polymers] The PGA-PMMA obtained above was dissolved in MMA to prepare the compositions according to the examples, and the properties of the compositions were confirmed. As for the properties, the flexural modulus and toughness of the cured product obtained by polymerizing the compositions were measured. For the compositions according to the examples, 0.6 g of PGA-PMMA was dissolved in 19.5 mL of MMA, and 20 g (Examples 1 and 2) or 10 g (Example 3) of polymer powder was added to the composition before polymerization. The polymer powder used was a powder mixed with 30.0 g of methylstyrene methacrylate copolymer, 6.0 g of PMMA, and 4.0 g of barium sulfate. In the polymerization of the compositions, 0.5 mL of N,N-dimethyl-p-toluidine was used as a polymerization initiator, and after mixing at room temperature (25°C), the reaction was allowed to proceed for one day. In addition, for the composition according to Comparative Example 1, MMA was used alone, and the flexural modulus and toughness of the cured product obtained by adding 20 g of the above polymer powder to 20.0 mL of MMA was measured. The flexural modulus of the hardened material was measured at room temperature (25°C) using the standard method of fixing both ends of the object and applying a load from the upper center. The toughness of the hardened material was calculated from the area of ​​the stress-strain graph obtained using a standard bending test, also performed at room temperature (25°C), with the same method of fixing both ends of the object and applying a load from the upper center.

[0069]

[0070] As shown in Table 1, the flexural modulus and toughness of the cured product obtained by polymerizing the compositions according to the examples (MMA, PGA-PMMA) are lower in flexural modulus and higher in toughness compared to the cured product in the comparative example. Therefore, when the compositions according to the examples are used in biomaterials, bone damage caused by the hardness of the cured product can be suppressed.

[0071] (Other) The graft polymers, compositions, curable materials (biomaterials), and cured products relating to this disclosure have been described above based on embodiments and examples. However, this disclosure is not limited to the above embodiments and examples. This disclosure also includes forms that can be obtained by applying various modifications to the above embodiments and examples that a person skilled in the art can conceive, and forms that can be realized by arbitrarily combining the components and functions of the above embodiments and examples without departing from the spirit of this disclosure.

[0072] For example, in the above embodiment, the biomaterial 10 was injected into the femur 40, but it is not limited to this. The biomaterial 10 may be injected into bones other than the femur 40, or it may be used as a bone filler for bone defects. Furthermore, the biomaterial 10 may be used as an adhesive for bone.

[0073] Examples of graft polymers, compositions, curable materials, and cured products relating to this disclosure, as described above based on the embodiments and examples, are shown below. The graft polymers, compositions, curable materials, and cured products relating to this disclosure are not limited to the following examples.

[0074] For example, the graft polymer according to the first aspect of this disclosure is a graft polymer in which a polymer of an acrylic monomer is grafted onto a biocompatible polymer.

[0075] Furthermore, for example, the graft polymer according to the second aspect of this disclosure is the graft polymer according to the first aspect, wherein the biocompatible polymer has carboxyl groups in its side chains.

[0076] Furthermore, for example, the graft polymer according to the third aspect of this disclosure is the graft polymer according to the first aspect, and the biocompatible polymer is polyglutamic acid.

[0077] Furthermore, for example, the graft polymer according to the fourth aspect of this disclosure is a graft polymer according to any one of the first to third aspects, wherein the acrylic monomer is a methacrylic acid ester.

[0078] Furthermore, for example, the graft polymer according to the fifth aspect of this disclosure is a graft polymer according to any one of the first to third aspects, wherein the acrylic monomer is methyl methacrylate.

[0079] Furthermore, for example, a composition according to the sixth aspect of the present disclosure comprises a graft polymer according to any one of the first to fifth aspects and an acrylic monomer, wherein the graft polymer is dissolved in the acrylic monomer.

[0080] Furthermore, for example, the curable material according to the seventh aspect of this disclosure includes the composition according to the sixth aspect and a polymerization initiator.

[0081] Furthermore, for example, the curable material according to the eighth aspect of this disclosure is the curable material according to the seventh aspect, which is a biomaterial injected into the bone.

[0082] Furthermore, for example, the cured product according to the ninth aspect of this disclosure is a cured product obtained by curing a curable material according to the seventh or eighth aspect.

[0083] The graft polymers, compositions, curable materials, and cured products relating to this disclosure can be used for applications such as increasing bone strength.

[0084] 10. Biomaterials 40. Femur

Claims

1. A graft polymer is a graft polymer in which a polymer of acrylic monomer is grafted onto a biocompatible polymer.

2. The biocompatible polymer is a graft polymer according to claim 1, wherein the biocompatible polymer has a carboxyl group in its side chain.

3. The graft polymer according to claim 1, wherein the biocompatible polymer is polyglutamic acid.

4. The graft polymer according to any one of claims 1 to 3, wherein the acrylic monomer is a methacrylic acid ester.

5. The graft polymer according to any one of claims 1 to 3, wherein the acrylic monomer is methyl methacrylate.

6. A composition comprising a graft polymer according to any one of claims 1 to 3 and an acrylic monomer, wherein the graft polymer is dissolved in the acrylic monomer.

7. A curable material comprising the composition according to claim 6 and a polymerization initiator.

8. The curable material according to claim 7, which is a biomaterial injected into the bone.

9. A cured product obtained by curing the curable material described in claim 7.

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