CN101235193A - Preparation method of degradable biocompatible polymer/carbon nanotube composite material - Google Patents

Abstract

The invention provides a preparation process of degradable biocompatible macromolecule/ carbon nano pipe composite material, relating to the preparation of biocompatible degradable macromolecule/ carbon nano pipe composite material which has high strength and high toughness. The invention adopts the technique of conducting surface activating, multiple phase solution dispersion, casing formation and heating processing for the carbon nano pipe with carboxylation and surface activator to prepare biological medical degradable polymer or carbon nano pipe composite material, which reduces the aggregation and entanglement phenomenon of the carbon nano pipe in solution, solves the problem of aggregating of the carbon nano pipe in macromolecules, forms firm interface interacting action with the polymer, thereby obviously increasing the mechanical property of degradable macromolecule. The carbon nano pipe/degradable macromolecule composite material with different dimension and shape which has high strength and high toughness can be obtained, in particular to reinforced polymer composite material of acidulating carbon nano pipe, wherein the tension strength is increased over 6.50 MPa, elasticity modulus is increased over 250 MPa, which has excellent surface wettability, adsorbability to protein and biomolecule, cellular affinity and biological degradation.

Description

Preparation method of degradable biocompatible polymer/carbon nanotube composite material

technical field

The invention relates to the field of biomedical materials, in particular to the preparation of high-strength and high-toughness biocompatible degradable polymer/carbon nanotube composite materials.

Background technique

Carbon nanotubes are closed nanotubes formed by bending single-layer or multi-layer six-membered carbon ring graphite layers. Both ends of the tube are hemispherically capped like half a fullerene molecule, and the aspect ratio is generally greater than 1000. . The unique structure of this new quasi-one-dimensional functional material makes it have excellent mechanical, electrical and thermal properties. The carbon-carbon bonds and closed structure of carbon nanotubes perfectly arranged in the axial direction lead to extremely high axial strength and elastic modulus. For example, the tensile strength of carbon nanotubes is about 100-600GPa, which is higher than that of existing high-strength carbon fibers. Two orders of magnitude, more than 100 times stronger than steel, the theoretical Young's modulus can be as high as 1.8×10 ¹² Pa, but the specific gravity is only 1/6-1/7 of steel, which is currently the material with the highest specific strength. In addition, carbon nanotubes are resistant to acids, alkalis, and high temperatures, and have high chemical and thermal stability. In recent years, a lot of research has been done on carbon nanotube-reinforced polymer composites at home and abroad, and it has been confirmed that carbon nanotubes, as a reinforcing phase and a conductive phase, can greatly improve the mechanical properties and other physical properties of polymers. The polymers involved include polystyrene, polyethylene, polymethyl methacrylate, polyamide, polyaniline, polyvinyl alcohol and dozens of other polymers.

Carbon materials have good biocompatibility, excellent anticoagulation and blood compatibility, do not affect the activity of proteins and enzymes in plasma; do not react, dissolve, corrode and other adverse reactions in the human body; in addition, there are Good lubricity and anti-fatigue properties, as well as the mechanical matching of human soft tissue and hard tissue, so it is widely used in hard tissue repair and cardiovascular materials.

Polyglycolic acid (PGA), polylactic acid (PLA), polyhydroxyalkanoic acid (PHA), polycaprolactate (PCL), polyanhydride and other degradable synthetic polymers, because of their good biocompatibility, and degradable The product is non-toxic and has a wide range of applications in the biomedical field, such as surgical sutures, absorbable bone fixation materials, drug slow-release materials, tissue engineering scaffold materials, and the like. However, these materials have deficiencies in mechanical properties, hydrophilicity, and cell affinity. Physical and chemical modification of these materials has always been a hot spot in the field of medical polymers.

Utilize the biocompatibility, excellent mechanical properties and physiological stability of carbon nanotubes, and compound them with the above-mentioned degradable biopolymers to prepare high-strength and high-toughness biocompatible degradable polymer/carbon nanotube composites, which can be used While maintaining the good biocompatibility and degradability of biopolymers, its mechanical properties and surface state are greatly improved, and biomedical materials with excellent performance can be obtained, which can be widely used in various soft/hard tissue regeneration and repair, as well as tissue engineering organs training etc.

Due to the large specific surface area and strong interaction of carbon nanotubes, it is very easy to spontaneously form rods with a diameter of 10-100nm. It is difficult to disperse uniformly, but exists in agglomerated state with large size, which affects the reinforcing effect and function of carbon nanotubes in the polymer matrix, as well as the forming and processing performance of polymer/carbon nanotube composites. None of the existing chemical modification and purification technologies can effectively solve this problem. Aiming at the above-mentioned present situation, the present invention adopts carbon nanotube surface activation, multi-phase solution dispersion, casting molding and heat treatment process to prepare biomedical degradable polymer/carbon nanotube composite material. Among them, a variety of surfactants and strong acids are used to activate the surface of carbon nanotubes, and hydrophilic or hydrophobic functional groups are introduced on the surface of carbon nanotubes to enhance the interfacial interaction between carbon nanotubes and degradable polymers, which is conducive to compounding. Stress transfer between two phases of a material. Using the multi-phase solution dispersion method under ultrasonic treatment, by selecting and controlling the solvent type, ultrasonic intensity and action time, mass fraction ratio of carbon nanotubes and polymers, reaction temperature, etc., the large ratio between carbon nanotubes can be broken. The agglomerated state formed by the surface area and strong interaction improves its dispersibility in solution and in the polymer matrix. In addition, by controlling the temperature, pressure and other conditions of casting and post-treatment, different aggregate structures and surface morphology can be obtained, so as to obtain mechanical properties, surface wettability, adsorption to proteins and biomolecules, and cell affinity and Medical biopolymer/carbon nanotube composites with tunable biodegradability.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a biocompatible medical biopolymer/carbon nanotube composite material, so that the prepared biocompatible degradable polymer/carbon nanotube composite material has excellent mechanical properties, Surface wettability, adsorption to proteins and biomolecules, cell affinity and biodegradability, and the above properties can be regulated according to the requirements of use.

The invention adopts surface activation, multi-phase solution dispersion, pouring molding and heat treatment process methods to prepare medical biopolymer/carbon nanotube composite material. The process steps are as follows:

Step 1: Surface activation of carbon nanotubes

Method 1: Add carbon nanotubes into a strong acid solution at 1-15g/L, stir and reflux for 3-12 hours at 70-140°C, and continue to reflux for 1-4 hours at room temperature; add deionized water to the strong acid solution And centrifuge to remove the acid remaining in the solution until the solution is basically neutral; then dry the solution for 12-24 hours to fully remove residual moisture; grind the obtained carbon nanotubes for 10-60min to obtain carboxylated carbon nanotubes ; The carbon nanotubes are single-walled carbon nanotubes with an outer diameter of ≤2 nm and a length of 1-15 μm, or multi-walled carbon nanotubes with an outer diameter of 5-100 nm and a length of 1-15 μm. The strong acid is concentrated sulfuric acid, or concentrated nitric acid, or a mixed acid of sulfuric acid and nitric acid in a volume ratio of 1/100-100/1, or a mixed acid of hydrochloric acid and nitric acid in a volume ratio of 1/100-100/1.

Method 2: At room temperature, prepare a solution of 0.001-5g/mL of analytically pure surfactant, etc., heat and stir in a water bath at 20-80°C until completely dissolved; add carbon nanotubes to the surfactant solution; disperse with ultrasound The instrument is intermittently processed for 1-60min, and the power of the ultrasonic wave is 50-450W. The weight percentage of the surfactant and the carbon nanotube is 0.5%-10%. The mixture was centrifuged, the water layer was removed, and placed in a vacuum oven. After fully drying to constant weight, grinding is carried out to obtain surface-activated carbon nanotubes. The surfactant is one of polyvinylpyrrolidone, sodium benzenesulfonate, sodium sulfonate, calcium sulfonate, ammonium sulfonate, sodium sulfate and betaine.

Step 2: Dispersion of carbon nanotube/polymer multiphase solution

Add the polymer into the following organic solvent at a concentration of 1-100mg/ml, and reflux in a water bath at 50-90°C until completely dissolved. Add the carboxylated carbon nanotubes or surface-activated carbon nanotubes obtained in step 1, the mass percentage of the added carbon nanotubes is 0.01%-20%, ultrasonically disperse for 2-60min, and the power of ultrasonically disperse is 50-450W to obtain a uniform Carbon nanotube/polymer multiphase solution. The polymer is one of polyglycolic acid (PGA), polylactic acid (PLA), polyhydroxyalkanoate (PHA), polycaprolactate (PCL), polyanhydride, polyamino acid, polyphosphazene, The organic solvent is one of dichloromethane, chloroform, tetrahydrofuran, xylene and acetone.

Step 3: Pouring molding and heat treatment

After the used mold is preheated at a temperature of 30-100° C., the multiphase solution obtained in step 2 is poured into the preheated mold and left to stand for 1-5 minutes to remove air bubbles in the solution. A large amount of solvent is evaporated at -5-90°C, and then dried at room temperature or directly at room temperature. The thickness of the film obtained after molding is 5-300 μm.

Compared with the prior art, the present invention uses carboxylation and surfactants to activate the surface of carbon nanotubes, the carbon nanotubes after activation reduce impurities, and the surface of carbon nanotubes is combined with carboxyl groups and surfactant groups, reducing carbon nanotubes. Aggregation and entanglement of nanotubes in solution. It can be uniformly dispersed in the biopolymer solution, which solves the problem of agglomeration of carbon nanotubes in the polymer, and forms a firm interfacial interaction with the polymer, significantly improving the mechanical properties of the degradable polymer. In addition, biomedical polymer/carbon nanotube composites are prepared by multi-phase solution dispersion, casting molding and heat treatment, which can control their surface morphology and aggregated structure. By changing the temperature and post-treatment conditions of the molding process, different Size and shape of high strength and toughness carbon nanotube/degradable polymer composites. Especially for the acidified carbon nanotube reinforced polymer composite, the tensile strength is increased from 3.88MPa to more than 6.50MPa, and the elastic modulus is increased from 145MPa to more than 250MPa (as shown in Figure 1 and Figure 2). In addition, the material has good surface wettability, adsorption to proteins and biomolecules, cell affinity and biodegradability (see Figure 3). In addition, the enhanced and toughened biocompatibility degradable polymer/carbon nanotube composite material prepared by the invention has simple process, convenient operation and good repeatability.

Description of drawings

Curve 1 is the stress-strain curve of polyhydroxybutyrate valerate among Fig. 1, and curve 2 is the stress-strain curve of acidified carbon nanotube reinforced polyhydroxybutyrate composite material;

Fig. 2 is the elastic modulus of material before and after compounding;

Figure 3 is the growth of cells on the composite film.

Detailed ways

Example one:

Add carbon nanotubes (multi-walled carbon nanotubes, inner diameter 80-100nm, length 1-2μm) into concentrated sulfuric acid at 3g/L, stir and reflux for 4 hours at 80°C, and continue to reflux for 1 hour at room temperature. Deionized water was added to the resulting solution and centrifuged to remove the acid remaining in the solution until the solution was substantially neutral. The solution was then dried for 12 hours to fully remove residual moisture. The obtained carbon nanotube powder was ground for 15 minutes to obtain acidified carbon nanotubes. Dissolve 1.5g of PHBV (containing 79% of PHV) in 60ml of chloroform, and reflux in a 50°C water bath until fully dissolved. Add 0.0045 g of carbon nanotubes treated with surfactant, and disperse by ultrasonic for 10 min. After the mold is preheated at a temperature of 40° C., the dispersed solution is poured into a petri dish and left to stand for 2 minutes. First evaporate a large amount of solvent under the condition of 70 ℃, and then dry and shape at room temperature.

Example two:

At room temperature, prepare an aqueous solution of polyvinylpyrrolidone with a concentration of 0.002g/mL, and dissolve in a water bath at 40°C. Add 0.7 g of carbon nanotubes (multi-walled carbon nanotubes, with an inner diameter of 40-60 nm and a length of 5-15 μm), and ultrasonically disperse for 15 min. The mixture was centrifuged, the water layer was removed, and placed in a vacuum oven. After fully drying to constant weight, grinding is carried out to obtain surface-activated carbon nanotubes. Dissolve 1.5g of polylactic acid in 60ml of acetone, and bathe in water at 40°C until fully dissolved. Add 0.0075 g of carbon nanotubes treated with surfactant, and disperse by ultrasonic for 10 min. After the mold is preheated at a temperature of 30°C, the dispersed solution is poured into a petri dish and left to stand for 3 minutes. A large amount of solvent is evaporated at 5°C, and then dried at room temperature for molding.

Example three:

Add carbon nanotubes (single-wall carbon nanotubes, inner diameter ≤ 2nm, length 1-2μm) into concentrated nitric acid solution at 3.5g/L, stir and reflux for 3.5 hours at 90°C, and continue to reflux for 2 hours at room temperature. Deionized water was added to the resulting solution and centrifuged to remove the acid remaining in the solution until the solution was substantially neutral. The solution was then dried for 12 hours to fully remove residual moisture. The obtained carbon nanotube powder was ground for 15 minutes to obtain acidified carbon nanotubes. Dissolve 1.5g of polycaprolactate in 60ml of xylene, and reflux in a water bath at 60°C until fully dissolved. Add 0.0075 g of carbon nanotubes treated with surfactant, and disperse by ultrasonic for 10 min. After the mold is preheated at a temperature of 50° C., the dispersed solution is poured into a petri dish and left to stand for 2 minutes. Dry and shape at room temperature.

Example four:

Add carbon nanotubes (multi-walled carbon nanotubes, inner diameter 80-100nm, length 1-2μm) into the mixed acid of sulfuric acid and nitric acid at 3.5g/L, stir and reflux at 90°C for 3.5 hours, and continue to reflux at room temperature for 3 Hour. Deionized water was added to the resulting solution and centrifuged to remove the acid remaining in the solution until the solution was substantially neutral. The solution was then dried for 20 hours to fully remove residual moisture. The obtained carbon nanotube powder was ground for 15 min to obtain carboxylated carbon nanotubes. Dissolve 1.5g of PHBV (containing PHV36%) in 60ml of chloroform, and reflux in a 60°C water bath until fully dissolved. Add 0.015 g of carbon nanotubes treated with surfactant, and disperse by ultrasonic for 10 min. After the mold was preheated at a temperature of 60°C, the dispersed solution was poured into a petri dish and left to stand for 2 minutes. First evaporate a large amount of solvent under the condition of 70 ℃, and then dry and shape at room temperature. After testing by a universal mechanical tensile testing machine, compared with the sample with the same composition but without adding carbon nanotubes, the elastic modulus and tensile strength of the composite material are significantly improved. In Fig. 1, curve 1 is the stress-strain curve of polyhydroxybutyrate valerate, curve 2 is the stress-strain curve of acidified carbon nanotube reinforced polyhydroxybutyrate composite material, and Fig. 2 is the elastic modulus of the material before and after compounding As can be seen from the figure, when the carbon nanotube content is 1wt%, the elastic modulus of the composite material increases from 144.9MPa to 297MPa, and the tensile strength increases from 3.87MPa to 6.97MPa.

Example five:

At room temperature, prepare an aqueous solution of sodium dodecylbenzenesulfonate with a concentration of 0.04 g/mL, and dissolve in a water bath at 50°C. Add 0.7 g of carbon nanotubes (multi-walled carbon nanotubes, inner diameter 80-100 nm, length 1-2 μm), and ultrasonically disperse for 15 min. The mixture was centrifuged, the water layer was removed, and placed in a vacuum oven. After fully drying to constant weight, grinding is carried out to obtain surface-activated carbon nanotubes. Dissolve 1.5g of polyglycolic acid in 60ml of dichloromethane, and bathe in 50°C water until fully dissolved. Add 0.0045 g of carbon nanotubes treated with a surfactant, and disperse ultrasonically for 15 minutes. After the mold was preheated at a temperature of 40°C, the dispersed solution was poured into a petri dish and left to stand for 1 min. A large amount of solvent is first evaporated in a drying oven, and then dried at room temperature to shape.

Claims (8)

1. A method for preparing a degradable biocompatible polymer/carbon nanotube composite material, characterized in that the preparation steps are as follows: 1) Surface activation of carbon nanotubes Choose one of the following methods: Method 1: Add carbon nanotubes into a strong acid solution at 1-15g/L, stir and reflux for 3-12 hours at 70-140°C, and continue to reflux at room temperature for 1-4 hours to remove the acid remaining in the solution until The solution is neutral, then the solution is dried for 12-24 hours, and the obtained carbon nanotubes are ground for 10-60 minutes to obtain carboxylated carbon nanotubes; Method 2: At room temperature, prepare a solution of 0.001-5g/mL of analytically pure surfactant, etc., heat and stir in a water bath at 20-80°C until completely dissolved, add carbon nanotubes to the surfactant solution, and disperse with ultrasound The instrument is intermittently treated for 1-60min, the weight percentage of surfactant and carbon nanotube is 0.5%-10%, the mixed solution is centrifuged, the water layer is removed, and placed in a vacuum drying oven, fully dried to constant weight, and then Grinding to obtain surface activated carbon nanotubes; 2) Dispersion of carbon nanotube/polymer multiphase solution Add the polymer into the organic solvent at a concentration of 1-100mg/ml, reflux in a water bath at 50-90°C until completely dissolved, add the carboxylated carbon nanotubes and surface-activated carbon nanotubes obtained in step 1, and add the carbon nanotubes The mass percentage of the tube is 0.01%-20%, and the ultrasonic dispersion is 2-60min to obtain a uniform carbon nanotube/polymer multiphase solution; 3) Pouring molding and heat treatment Pour the multiphase solution obtained in step 2 into a preheated mold, let it stand for 1-5 minutes, remove the air bubbles in the solution, evaporate the solvent at -5-90°C, and then dry it to shape. 2. The preparation method of polymer/carbon nanotube composite material according to claim 1, characterized in that, removing the acid remaining in the solution is to add deionized water to the strong acid solution, and then centrifuge. 3. The method for preparing a polymer/carbon nanotube composite material according to claim 1, wherein the carbon nanotubes are single-walled carbon nanotubes with an outer diameter of ≤2 nm and a length of 1-15 μm, or more Walled carbon nanotubes with an outer diameter ranging from 5-100 nm and a length of 1-15 μm. 4. The method for preparing a polymer/carbon nanotube composite material according to claim 1, wherein the strong acid is concentrated sulfuric acid, or concentrated nitric acid, or a mixture of sulfuric acid and nitric acid in a volume ratio of 1/100-100/1 acid, or a mixed acid of hydrochloric acid and nitric acid in a volume ratio of 1/100-100/1. 5. The preparation method of polymer/carbon nanotube composite material according to claim 1, characterized in that the ultrasonic power of ultrasonic dispersion is 50-450W. 6. The method for preparing polymer/carbon nanotube composites according to claim 1, wherein the surfactant is polyvinylpyrrolidone, sodium benzenesulfonate, sodium sulfonate, calcium sulfonate, sulfonic acid One of ammonium, sodium sulfate, and betaine. 7. The method for preparing a polymer/carbon nanotube composite material according to claim 1, wherein the polymer described in step 2 is polyglycolic acid, polylactic acid, polyhydroxyalkanoate, polycaprolactic acid One of ester, polyanhydride, polyamino acid, polyphosphazene, and the organic solvent is one of methylene chloride, chloroform, tetrahydrofuran, xylene, acetone. 8. The preparation method of polymer/carbon nanotube composite material according to claim 1, characterized in that the thickness of the film obtained after molding is 5-300 μm.

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