Polymer / magnesium composite based on self-passivation regulation of interface microcrack reactor and preparation thereof

Abstract

This invention relates to a composite material and its preparation method, which utilizes interfacial microcracks in a polymer / magnesium-based biodegradable metal composite material as a reactor to spontaneously induce the formation of an alkaline mineral passivation layer on one side of the hybrid surface of the composite material, thereby regulating the corrosion of the magnesium-based biodegradable metal. The composite material of this invention comprises a magnesium-based biodegradable metal and a polymer, which are composited through physical means. After composite formation, microcracks are formed at the polymer / magnesium-based biodegradable metal interface. When the material is exposed to body fluids, the metal at the crack sites undergoes corrosion and degradation. The released magnesium ions and hydroxide ions are confined within the microcracks, and their concentration rapidly reaches supersaturation in the confined space. Metal hydroxide nuclei form with the cracks as preferential sites and grow bidirectionally on both sides of the interface, spontaneously forming an alkaline passivation layer, which can effectively slow down the corrosion rate of the magnesium-based biodegradable metal in a humid environment.

Description

Technical Field

[0001] This invention belongs to the field of medical material manufacturing technology, and relates to a polymer / magnesium composite material based on the self-passivation regulation of an interfacial microcrack reactor and its preparation. Background Technology

[0002] Biodegradable metals possess biodegradability, excellent mechanical strength, ductility, formability, osteogenic capacity, and antibacterial properties, making them a promising class of bone implant materials. Controlling their degradation is a precursor to achieving their ideal biological properties.

[0003] Research on magnesium as a surgical implant material dates back to the early 20th century. Early clinical applications confirmed the biocompatibility of magnesium and its feasibility for use in biomedical materials. Magnesium is an essential element for human life, participating in almost all metabolic processes within the body. Furthermore, magnesium is one of the most abundant light elements on Earth, including in the oceans, and is inexpensive, making it an essential nutrient for the human body. It can catalyze or activate 325 enzyme systems in the body, participate in all energy metabolism, and play a vital role in muscle contraction, neuromotor function, and physiological functions. Magnesium has an elastic modulus of 45 GPa, lower than other biomedical materials and closer to that of bone, effectively mitigating the stress shielding effect; its density is typically 1.7 g / cm³. 3 Compared to natural bone density of 1.75 g / cm³ 3 Similar to, but much lower than, the density of Ti-6Al-4V (4.47 g / cm³). 3 Magnesium exhibits excellent biomechanical compatibility. Furthermore, it is biodegradable in the human body, avoiding the need for secondary surgeries, secondary infections, and additional costs associated with other commonly used biomaterials.

[0004] However, magnesium has a very low standard electrode potential (-2.37V), and its corrosion resistance is even worse in the human physiological environment containing chloride ions. Problems such as excessively high corrosion (degradation) rates and localized corrosion in magnesium-based materials can easily lead to premature loss of mechanical integrity and support, thus limiting their application in clinical treatment, especially in orthopedic weight-bearing areas. The corrosion of magnesium is related to impurity elements and their tolerance limits; the more impurities, the more severe the corrosion. Therefore, improving the purity of magnesium significantly improves its corrosion resistance. Alloying is another method to improve the corrosion resistance of magnesium. By adding appropriate alloying elements, grain refinement can be achieved, improving the type, morphology, size, and distribution of the second phase, thereby reducing the alloy's corrosion tendency in corrosive media. Processing techniques such as rapid solidification, powder metallurgy, heat treatment, and deformation processing can improve the corrosion resistance of magnesium-based materials to some extent. In addition to altering the material's inherent corrosion resistance, surface modifications such as coatings can also improve the corrosion resistance of medical magnesium-based implant materials to some extent. However, these methods all have shortcomings: ultrapure purification is costly, and alloying and coating introduce new uncertainties. From the perspective of the corrosion properties of magnesium itself, it remains a challenge to achieve controllability of the degradation rate and degradation mode of magnesium-based implant materials and further improve their corrosion resistance while ensuring biocompatibility and safety.

[0005] Therefore, there is an urgent need for a strategy to achieve precise degradation regulation of biomedical magnesium-based biodegradable metals. Summary of the Invention

[0006] The purpose of this invention is to disclose a polymer / magnesium composite material based on the self-passivation regulation of an interfacial microcrack reactor, which aims to regulate magnesium degradation and improve the biocompatibility of medical composite materials.

[0007] The composite material comprises a polymer and a magnesium-based biodegradable metal. Furthermore, the magnesium-based biodegradable metal can be replaced by a zinc-based biodegradable metal or an iron-based biodegradable metal.

[0008] The polymer and magnesium-based biodegradable metal are composited through physical interactions. The resulting composite material has a polymer / magnesium hybrid surface. Numerous microcracks exist at the polymer / magnesium composite interface.

[0009] Furthermore, the magnesium-based biodegradable metals include pure magnesium and magnesium alloys.

[0010] Furthermore, the polymers include non-degradable polymers and degradable polymers.

[0011] Non-degradable polymers, including polyaryletherketone polymers, polyacetal polymers, polyolefin polymers, and other inert synthetic polymers, including but not limited to polymethyl methacrylate, polyurethane, silicone rubber, polytetrafluoroethylene, polyvinylidene fluoride-trifluoroethylene copolymer, polyimide, and polyethylene terephthalate.

[0012] Degradable polymers include, but are not limited to, polylactic acid, polyglycolic acid, polybutylene adipate terephthalate, polybutylene succinate, polycaprolactone, polypropylene carbonate, polylactic acid-glycolic acid copolymer, polycaprolactone-polylactic acid copolymer, polycaprolactone-polyethylene glycol copolymer, polylactic acid-polyethylene glycol copolymer, polyurethane-polyethylene glycol copolymer, and polyhydroxy fatty acid ester copolymers.

[0013] Another object of the present invention is to provide a method for preparing the polymer / magnesium composite material, comprising, but not limited to, combining the polymer with a biodegradable metal through methods such as hot pressing, cold pressing, extrusion, dripping, blow molding, injection molding, leveling, printing, thermoplasticizing, calendering, foaming, rotational molding, and solid-state molding to achieve physical bonding between the two. Specifically, the method includes the following steps: (1) Preparation of magnesium-based biodegradable metals with macroscopic shapes; (2) Heating puts the polymer into a plastic state; (3) The polymer in a plastic state is tightly wrapped with magnesium-based biodegradable metal by means of hot pressing, cold pressing, extrusion, dripping, blow molding, injection molding, leveling, printing, thermoplasticizing, calendering, foaming, rotational molding, solid-state molding and other methods.

[0014] In a humid environment, microcracks act as microreactors, restricting the diffusion of metal ions and hydroxide ions released during corrosion. Hydroxide nuclei are spontaneously formed at the interface between the two, and the nuclei grow simultaneously to both sides of the interface, thereby automatically forming a self-passivating alkaline mineral layer on the surface of the composite material, effectively slowing down the corrosion rate of degradable metals in a humid environment.

[0015] The polymer and magnesium-based biodegradable metal are composited through physical interactions. The resulting composite material has a polymer / magnesium hybrid surface. Numerous microcracks exist at the polymer / magnesium composite interface.

[0016] Another object of the present invention is to provide the application of the aforementioned polymer / magnesium composite material in the preparation of bone implant materials. This involves a self-passivation control mechanism based on an interfacial microcrack reactor constructed using a simple physical method. On the surface of the polymer / magnesium-based biodegradable metal hybrid, microcracks are formed at the polymer / metal interface. These microcracks can act as microreactors, limiting the formation of supersaturated magnesium ions and hydroxide ions generated during corrosion in humid environments. This preferentially leads to the formation of insoluble crystal nuclei at the interface, which grow simultaneously to both sides of the interface. This spontaneously induces the formation of an alkaline mineral passivation layer on the surface of the composite material, effectively slowing down the corrosion rate of the magnesium-based biodegradable metal in humid environments.

[0017] The technical solution of this invention has the following beneficial effects: 1. Improve the controllability of degradation of biodegradable metals: Degradation releases metal ions and OH groups. -Confined within the fissures, it rapidly reaches supersaturation, forming insoluble metal hydroxide precipitates at the polymer / metal interface to slow down metal degradation.

[0018] 2. Unlike coating methods that improve corrosion resistance, the composite material treated by the technical solution of this invention can obtain a spontaneously formed dynamic protective layer, thereby providing long-lasting protection for degradable metals.

[0019] 3. The preparation method provided by this invention is simple, and this invention can regulate the magnesium degradation rate by adjusting the number of microcracks exposed in the polymer / magnesium, which has broad application prospects.

[0020] 4. This invention not only effectively improves the corrosion resistance of biodegradable metals used in biomedicine, but also further enhances the biocompatibility and bioactivity of the composite material, thus expanding its application scope. Attached Figure Description

[0021] Figure 1 These are the electron microscope and energy dispersive spectroscopy (EDS) images of Examples 1-3.

[0022] Figure 2 This is a scanning electron microscope image of in vitro degradation.

[0023] Figure 3 It is the release of magnesium ions due to in vitro degradation.

[0024] Figure 4 It refers to pH changes during in vitro degradation.

[0025] Figure 5 It is the release of hydrogen gas from in vitro degradation.

[0026] Figure 6 It is an in vitro degradation energy spectrum.

[0027] Figure 7 It is an in vitro degradation Raman spectrum.

[0028] Figure 8 It is an in vitro degradation micro-region XRD.

[0029] Figure 9 It is indicated by phenol red agar.

[0030] Figure 10 This is a general diagram of in vitro degradation.

[0031] Figure 11 It refers to pH changes during in vitro degradation.

[0032] Figure 12 It is the release of magnesium ions due to in vitro degradation. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. The embodiments of the present invention are only for better illustrating the features of the present invention and do not fully encompass the content protected by this patent. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0034] Comparative Example 1: Porous pure magnesium mesh was prepared using a machining method: 99% pure magnesium metal was processed into a 0.2 mm thick metal film through solution treatment, extrusion, and aging. Using a precision high-speed punch press placed in a mold, and combined with continuous stamping technology, uniform holes with a diameter of 300 μm were punched into the surface of the metal film. The film was cooled with a special cutting fluid, and then ultrasonically cleaned and dried after processing.

[0035] Comparative Example 2: Porous pure magnesium mesh was prepared using a machining method: 99% pure magnesium metal was processed into a 0.2 mm thick metal film through solution treatment, extrusion, and aging. Using a precision high-speed punch press placed in a mold, and combined with continuous stamping technology, uniform holes with a diameter of 500 μm were punched into the surface of the metal film. The film was cooled with a special cutting fluid, and then ultrasonically cleaned and dried after processing.

[0036] Comparative Example 3: Porous pure magnesium mesh was prepared using a machining method: 99% pure magnesium metal was processed into a 0.2 mm thick metal film through solution treatment, extrusion, and aging. Using a precision high-speed punch press placed in a mold, and combined with continuous stamping technology, holes with a diameter of 800 μm were uniformly punched on the surface of the metal film. The mesh was cooled with a special cutting fluid, and after processing, it was ultrasonically cleaned and dried.

[0037] Comparative Example 4: P(VDF-TrFE) copolymer powder was dissolved in dimethylformamide (DMF) and heated at 200-220°C for 20 minutes to form a sol. The sol was then hydraulically pressed at 20 tons of force for 15 minutes to obtain a P(VDF-TrFE) film with a thickness of 0.1 mm.

[0038] Comparative Example 5: Based on Comparative Example 2, a calcium phosphate coating was constructed using an alkaline thermal method. Pretreated magnesium was placed in an alkaline treatment solution with a pH of 8.5-9.5 and subjected to alkaline thermal treatment at 80-100°C for 0.5-4 hours. The treatment solution contained a calcium ion source and a phosphate source.

[0039] Example 1: The porous magnesium mesh obtained in Comparative Example 1 was placed on the P (VDF-TrFE) membrane obtained in Comparative Example 4. After heating in an oven at 220°C for 20 min, it was hydraulically pressed for 15 minutes under 20 tons of force. After natural cooling, a porous magnesium Mg / P (VDF-TrFE) composite membrane was obtained.

[0040] Example 2: The porous magnesium mesh obtained in Comparative Example 2 was placed on the P (VDF-TrFE) membrane obtained in Comparative Example 4. After heating in an oven at 220°C for 20 minutes, it was hydraulically pressed for 15 minutes under 20 tons of force. After natural cooling, a porous magnesium Mg / P (VDF-TrFE) composite membrane was obtained.

[0041] Example 3: The porous magnesium mesh obtained in Comparative Example 3 was placed on the P (VDF-TrFE) membrane obtained in Comparative Example 4. After heating in an oven at 220°C for 20 minutes, it was hydraulically pressed for 15 minutes under a force of 20 tons. After natural cooling, a porous magnesium Mg / P (VDF-TrFE) composite membrane was obtained.

[0042] Example 4: Examples 1-3 were observed using scanning electron microscopy and subjected to energy dispersive spectroscopy analysis. Figure 1 ).

[0043] The samples from Examples 1-3 and Control Examples 1-3 were divided according to a surface area of ​​3 cm². 2 / ml was immersed in simulated body fluid and maintained at 37.0±0.5℃. The samples were removed after 3, 7, 14 and 28 days for scanning electron microscopy observation. Figure 2 ), and detect the magnesium ion concentration in the soaking solution ( Figure 3 pH changes Figure 4 ) and hydrogen release ( Figure 5 As can be seen, combining it with P (VDF-TrFE) significantly slows down the degradation of magnesium and improves corrosion resistance.

[0044] The samples from Example 2 and Control Example 2 were compared according to a surface area of ​​3 cm². 2 / ml was immersed in simulated body fluid and maintained at 37.0±0.5℃ for 12, 24, and 72 hours. The samples were then removed and observed using an energy dispersive spectroscopy (EDS) instrument. Figure 6 ), micro Raman detection ( Figure 7 ) and micro-area XRD detection ( Figure 8 As can be seen, Mg(OH)2 first appears at the edge of the pores of the P(VDF-TrFE)-magnesium composite and gradually covers the entire implant material.

[0045] Samples from Example 2 and Control Example 2 were placed in well plates, and phenol red-labeled agar solution was added. After solidification, the plates were placed at 37.0±0.5℃ and observed continuously for 24 hours. Images were taken and recorded using a stereomicroscope. Figure 9 It can be seen that by combining with P (VDF-TrFE) to form microcracks, the pH around the microcracks is significantly higher than that of the non-compliance group.

[0046] The samples from Comparative Example 2, Comparative Example 5, and Example 2 were compared according to a surface area of ​​3 cm². 2 / ml was immersed in simulated body fluid and maintained at 37.0±0.5℃. After 1, 3, 7 and 14 days, the sample was removed for gross observation. Figure 10 ), and detect the magnesium ion concentration in the soaking solution ( Figure 11 pH changes Figure 12 As can be seen, compared with coating technology, the solution of this invention can achieve more stable and longer-lasting corrosion resistance.

[0047] Example 4 A pure magnesium column with a diameter of 1 mm was pressed into molten polyether ether ketone (PEEK) to form microcracks at the magnesium column / PEEK composite interface, thus constructing a magnesium-activated PEEK implant.

[0048] Example 5 Magnesium-zinc nails with a diameter of 1.5 mm are hammered into polyetheretherketone (PEEK) with a pre-drilled 1.4 mm aperture, forming microcracks at the zinc nail / PEEK composite interface to construct a magnesium-activated PEEK implant.

[0049] Example 6 A magnesium-strontium alloy wire with a diameter of 0.5 mm was coiled into a spiral shape, and polyetherketone ketone was 3D printed on top of it, forming microcracks at the magnesium wire / polyetherketone ketone composite interface to construct magnesium-activated polyetherketone ketone.

[0050] Example 7 A 1 mm diameter magnesium-iron wire is coiled into a spiral shape and then hot-pressed together with polyethylene glycol to form microcracks at the zinc wire / polyethylene glycol composite interface.

[0051] Example 8 Pure magnesium wire with a diameter of 0.5 mm is coiled into a spiral shape and then hot-pressed with polytetrafluoroethylene (PTFE) to form microcracks at the magnesium wire / PTFE composite interface, thus constructing magnesium-reinforced PTFE.

[0052] Example 9 Magnesium-titanium alloy mesh is composited with polytetrafluoroethylene by hot pressing.

[0053] Example 10 Magnesium-zinc-calcium wire alloy with a diameter of 0.3 mm was pressed into molten polyetheretherketone (PEEK) to form microcracks at the magnesium pillar / PEEK composite interface, thus constructing a magnesium-activated PEEK implant.

[0054] Example 11 3D printed magnesium-zinc-zirconium alloy mesh is composited with polytetrafluoroethylene via hot pressing.

[0055] Example 12 Mg-Al-Zn alloy nails are composited with polyether ketone ketone via injection molding.

Claims

1. A polymer / magnesium composite material based on self-passivation regulation of an interfacial microcrack reactor, characterized in that, The composite material contains a polymer and a magnesium-based biodegradable metal. The two phases are physically combined to form a polymer / magnesium-based biodegradable metal hybrid surface.

2. The polymer / magnesium composite material according to claim 1, characterized in that, The magnesium-based biodegradable metals include pure magnesium and magnesium alloys.

3. The polymer / magnesium composite material according to claim 1, characterized in that, The polymers include non-degradable polymers or degradable polymers.

4. The polymer / magnesium composite material according to claim 1 or 2, characterized in that, The magnesium-based biodegradable metal is tightly wrapped by the polymer, while some parts are exposed.

5. The polymer / magnesium composite material according to claim 1 or 2, wherein the magnesium-based biodegradable metal has any macroscopic shape as a block, film, nail, porous mesh, or filament.

6. The polymer / magnesium composite material according to claim 1, characterized in that, On the polymer / magnesium-based biodegradable metal hybrid surface, microcracks are formed at the polymer / metal interface. These microcracks can act as microreactors, which can limit the formation of supersaturation of magnesium ions and hydroxide ions generated by corrosion in a humid environment. This results in the preferential formation of insoluble crystal nuclei at the interface, which grow simultaneously to both sides of the interface. An alkaline mineral passivation layer is spontaneously induced to form on the surface of the composite material, effectively slowing down the corrosion rate of magnesium-based biodegradable metals in a humid environment.

7. The method for preparing polymer / magnesium composite materials based on self-passivation regulation of interfacial microcrack reactor according to any one of claims 1 to 6, characterized in that, It includes the following steps: (1) Preparation of magnesium-based biodegradable metals with macroscopic shapes; (2) Heating puts the polymer into a plastic state; (3) The polymer in a plastic state is tightly wrapped with magnesium-based biodegradable metal by means of hot pressing, cold pressing, extrusion, dripping, blow molding, injection molding, leveling, printing, thermoplasticizing, calendering, foaming, rotational molding, solid-state molding and other methods.

8. The preparation method according to claim 7, characterized in that, The polymer's malleable state includes a molten state and a rubbery state.

9. The use of the polymer / magnesium composite material according to claim 1 in the preparation of bone implant materials.

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