CN114808179B - Composite material with controllable relaxation time and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the field of functional fiber materials, and discloses a composite material with controllable relaxation time, a preparation method and application thereof. The organic hydrogen-containing molecular contrast agent is loaded in the pores of the polymer material by electrospinning technology, so that the organic hydrogen-containing molecular contrast agent is confined, thereby reducing the relaxation time of its hydrogen atoms. Without adding additional substances, the relaxation time of the organic hydrogen-containing molecular contrast agent can be adjusted only by changing the structure of the loaded polymer material. Compared with the disclosed technology, it has the characteristics of high biological safety, non-toxicity, non-allergy and wide application range. It can be used in the preparation of polymeric MRI contrast agents, standard relaxation time samples, and standard MRI signal intensity materials.

Description

A composite material with controllable relaxation time and its preparation method and application

technical field

The invention belongs to the field of functional fiber materials, and more specifically relates to a composite material with controllable relaxation time and its preparation method and application.

Background technique

Magnetic Resonance Imaging (MRI)

Magnetic resonance refers to the physical phenomenon that atomic nuclei resonate with an external magnetic field under certain conditions. The basic working principle of magnetic resonance imaging (MRI) is to place the measured object in a special magnetic field, and use radio frequency pulses to excite the hydrogen nuclei in the object, causing the hydrogen nuclei to resonate and absorb energy. After stopping the radio frequency pulses, the hydrogen nuclei release the absorbed energy, emitting a radio signal at a specific frequency. This radio signal is picked up by a receiver in the MRI machine and processed by a computer to create an image. At present, the signals collected by human MRI equipment are mainly from hydrogen atoms (see Yang Zhenghan et al. "Magnetic Resonance Imaging Technology Guide", People's Military Medical Press, 2010: P18-19).

MRI signal intensity and relaxation time

Hydrogen atoms in different environments (such as being bonded, in pores, high temperature, etc.), after being excited by radio frequency pulses, release energy at different speeds when returning to the ground state. This energy release process is called relaxation. There are two independent processes of relaxation, which are called T1 and T2 relaxation (or transverse and longitudinal relaxation). The time required for the two relaxation processes to occur is called are T1 and T2 relaxation times.

MRI has a variety of scanning sequences used to obtain signals, the most commonly used sequences are T1WI (T1-weighted imaging), T2WI (T2-weighted imaging), PDWI (proton-weighted imaging), DWI (diffusion-weighted imaging), etc., and these commonly used The signal intensity of the image obtained by the scanning sequence is affected by the relaxation time of hydrogen atoms T1 and T2, that is to say, the signal intensity of hydrogen atoms with different relaxation times on the MRI image is different (see Ray H.Hashemi et al . MRI: The Basics. Lippincott Williams & Wilkins, 2012, p54-55).

Polymer materials cannot generate sufficient MRI signal

Polymer materials have been widely used in the manufacture of medical devices, but the T2 relaxation time of hydrogen atoms contained in polymer materials is too short, in the range of tens of milliseconds or even tens of nanoseconds. MRI is difficult to detect hydrogen atoms with such a short relaxation time due to the limitations of its own equipment, so that polymers in the human body cannot be imaged by MRI. This phenomenon can be seen in the research of Yuan et al. (Yuan D C et al. Journal of Biomedical Materials Research Part B-Applied Biomaterials, 2019, 107(7): 2305-2316). Butylene terephthalate-butylene terephthalate) fibers were used as artificial discs to replace the nucleus pulposus, but they were completely signalless under MRI. This problem makes it difficult for doctors to obtain the information of implanted polymer materials in the patient's body through MRI, which brings obstacles to treatment.

Published imaging techniques and their drawbacks

There are many types of MRI contrast techniques, one of which is the use of contrast agents. MRI contrast agents can be classified into two categories according to the type of molecules that provide signals: (1) Water molecules, which shorten the T1 and T2 relaxation times of water molecules through magnetic contrast agents, thereby changing the MRI signal intensity. The signal intensity of the water molecules at the position where the contrast agent is located changes significantly, thereby providing sufficient signal contrast for the position. This type of contrast agent is the most common; (2) organic hydrogen-containing molecules such as fats, vegetable oils, and sucrose polyesters (see "Guidelines for Magnetic Resonance Imaging Techniques" by Yang Zhenghan et al., People's Military Medical Press, 2010: P390), these molecules They have a unified feature that they always have long-chain fatty groups in their molecular composition, because the hydrogen in long-chain fat is the source of their MRI signals. The hydrogen in these molecules is a natural source of high MRI signal intensity.

For the (2) class of organic hydrogen-containing molecular contrast agents, since the relaxation time is the property of the substance itself, the relaxation time (ie, the MRI signal intensity) of the organic hydrogen-containing molecule is not adjustable when it only exists by itself. , can only be expressed as a single value. However, for polymer implanted medical devices used in different parts of the human body, the MRI signal intensity required for imaging is different, and the organic hydrogen-containing molecular contrast agent that can only be expressed as a single signal intensity, in the face of the MRI signal intensity varies with the use environment. When varying conditions are required, the performance of organic hydrogen-containing molecules is not sufficient for variable signal strength.

Contents of the invention

For the defects of the disclosed technology, the purpose of the present invention is to: (1) provide a preparation method of a composite material with controllable relaxation time; (2) provide the application of this kind of composite material; The control of the relaxation time of the organic hydrogen-containing molecular contrast agent in the material can meet the MRI contrast requirements of polymer materials.

The method and principle of the present invention to control the relaxation time of organic hydrogen-containing molecules are as follows:

The relaxation time of a substance is mainly determined by its molecular structure and state of matter (such as solid, liquid, gas). However, the environment of the molecule will also affect its relaxation time. For example, the relaxation time of water molecules in different pore sizes will change due to being limited by the pore wall. Therefore, the relaxation time of water molecules can be used to determine Measure the hole size. Similarly, by constructing a polymer matrix with a pore structure, the relaxation time of the organic hydrogen-containing molecular contrast agent confined inside the polymer pore can be controlled. Organic hydrogen-containing molecular contrast agents contain a large number of hydrogen atoms. When they are confined in the pores formed by polymers, the molecules will collide with the walls of the polymer pores during motion, shortening the relaxation time of the hydrogen atoms, thereby changing the Its MRI signal.

The object of the invention is achieved through the following specific technical solutions:

A method for preparing a composite material with controllable relaxation time, comprising the steps of:

(S1) preparing spinning solution: dissolving the polymer material in a solvent to form a polymer solution, and dissolving an organic hydrogen-containing molecular contrast agent in a solvent to form a contrast agent solution;

(S2) mixing the two solutions for electrospinning;

(S3) drying the collected composite fiber product, immersing it in water, exhausting the air in the fiber, and obtaining a composite material with a controllable relaxation time.

The polymer material described in step (S1) is polyester polymer and its derivatives, polyolefin polymer and its derivatives, polyamide polymer and its derivatives, starch and its derivatives, cellulose And its derivatives, chitosan, polyoxymethylene, hyaluronic acid, fibrin, silk fibroin, one or more than two kinds of blended copolymers and block copolymers of the above polymers are mixed.

Preferably, the polyester polymer and its derivatives are polyglycolide, polylactic acid, polycaprolactone, polyglycolic acid, polymethyl methacrylate, polyethylene terephthalate, polyethylene terephthalate At least one of butylene formate and polycarbonate; polyolefin polymers and their derivatives are polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyisoprene, polyvinylpyrrolidone, At least one of polyvinyl alcohol and polyacrylonitrile; polyamide polymer and its derivatives are at least one of nylon 6, nylon 66, nylon 610, and nylon 1212; starch and its derivatives are hydroxyethyl starch and/or carboxymethyl starch; cellulose and its derivatives are cellulose acetate, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose, hydroxypropyl At least one of methyl cellulose; blended copolymers and block copolymers are L-D-polylactic acid copolymers, polyethylene glycol-polylactic acid block copolymers, polyethylene glycol-polycaprolactone Block copolymer, polyethylene glycol-polyvinylpyrrolidone block copolymer, polystyrene-polybutadiene block copolymer, styrene-butadiene-styrene triblock copolymer, polystyrene- Poly(ethylene-butylene)-polystyrene block copolymer, styrene-isoprene/butadiene-styrene block copolymer, polystyrene-polybutadiene-polystyrene block copolymer at least one of the

The organic hydrogen-containing molecular contrast agent described in the step (S1) is one or both of long-chain fatty monobasic acid, long-chain fatty monohydric alcohol, monobasic acid monohydric alcohol long-chain fatty ester, and monobasic acid polyhydric alcohol long-chain fatty ester. A mixture of the above.

Preferably, the long-chain fatty monobasic acid is a fatty monobasic acid with a carbon number of 8 to 24; the long-chain fatty monohydric alcohol is a fatty monohydric alcohol with a carbon number of 8 to 16; The ester of chain fatty monobasic acid and long-chain fatty monohydric alcohol with 8 to 28 carbons; the monobasic acid polyalcohol long-chain fatty ester is composed of glycerol, sucrose, glucose, fructose and the ester with 8 to 18 carbons Esters of long-chain fatty monobasic acids.

More preferably, the fatty monobasic acid containing 8 to 24 carbons is n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, n-dodecanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, isodecanoic acid At least one of monocarbonic acid, isododecanoic acid, myristic acid, palmitic acid, stearic acid, oleic acid, vaccinic acid, cisapinic acid, and nervonic acid; fatty monohydric alcohols containing 8 to 16 carbons are n-octanol, n-nonanol, n-decyl alcohol, n-undecyl alcohol, n-dodecyl alcohol, n-tridecyl alcohol, n-tetradecyl alcohol, n-pentadecanol, n-hexadecanol, isooctyl alcohol, isononyl alcohol, At least one of isodecyl alcohol, isoundecanol, isododecanol, isotridecanol, isotetradecyl alcohol, and isopentadecyl alcohol; monobasic acid monoalcohol long-chain fatty esters containing 8 to 28 carbons Octyl octanoate, nonyl nonanoate, decyl caprate, undecyl undecyl carbonate, dodecyl dodecyl carbonate, tridecyl tridecyl carbonate, tetradecyl tetradecanoate, methyl caprate, capric acid Ethyl caprate, propyl caprate, butyl caprate, pentyl caprate, hexyl caprate, heptyl caprate, octyl caprate, nonyl caprate, methyl dodecanoate, ethyl dodecanoate, Propyl Dicarbonate, Butyl Dodecyl Carbonate, Pentyl Dodecyl Carbonate, Hexyl Dodecyl Carbonate, Heptyl Dodecyl Carbonate, Octyl Dodecyl Carbonate, Nonyl Dodecyl Carbonate, Decyl Dodecyl Carbonate, Dodecyl Carbonate At least one of undecyl esters. The ester compounds formed by glycerol, sucrose, glucose, fructose and long-chain fatty monobasic acids with carbon numbers from 8 to 18 are mono/di/tricaprylic glycerides, mono/di/tricapric glycerides, mono/dicaprylic acid glycerides, Glyceryl Di/Trilaurate, Glyceryl Mono/Dis/Tripostearate, Glyceryl Mono/Di/Tripalmitate, Sucrose/Glucose/Fructose Caprate, Sucrose/Glucose/Fructose Laurate, Sucrose/Glucose /at least one of fructose stearate.

The solvent described in step (S1) is solvent pentane, n-hexane, methylcyclohexane, methylene dichloride, chloroform, ethylene dichloride, tetrachloroethane, carbon tetrachloride, methyl acrylate, Tetrahydrofuran, methyl tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, diethyl ether, petroleum ether, acetone, formic acid, acetic acid, trifluoroacetic acid, hexafluoroiso Propanol, xylene, toluene, phenol, chlorobenzene, nitrobenzene, cresol, anisole, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, pentanol one or a mixture of two or more.

The concentration of the polymer solution in step (S1) is 5-45 wt%, and the concentration of the contrast agent solution is 20-90 wt%.

The electrospinning conditions described in step (S2) are: the liquid supply rate of the liquid supply device is 0.1-10mL/h, the distance between the spinneret and the collection device is 5-50cm, the spinneret is connected to a high voltage of 10-50kV, and the collection device is connected to a high voltage of 10-50kV. Connect to high voltage 0~-50kV.

The reason for exhausting the air in the fiber described in step (S3) is that the magnetic permeability of the air and the polymer composite fiber is significantly different, which will affect the inhomogeneity of the magnetic field and cause the MRI imaging effect to deteriorate, so there cannot be air residual.

In the final composite fiber product described in step (S3), the relaxation time of the organic hydrogen-containing molecular contrast agent in the composite fiber can be reduced to 10% of its bulk at most, and can be changed continuously.

A composite fiber is prepared by the above method. The composite fibers prepared by the above process can be applied to: (1) provide MRI signals for polymer materials; (2) provide samples with standard relaxation times for equipment calibration; (3) serve as samples with standard MRI signal strengths The implant material is used for MRI signal calibration in the human body.

Compared with the disclosed technology, the preparation method and the resulting product of the present invention have the following advantages and beneficial effects:

(1) The disclosed technologies all use metal-containing contrast agents (chelates, nanoparticles, etc.) to change the relaxation time of hydrogen atoms, but these substances have certain toxicity or sensitization, and the method of the present invention only changes The structure of the polymer can regulate the relaxation time of the hydrogen atom, and no other substances are introduced, which has higher safety;

(2) The electrospinning equipment adopted in the method of the present invention is simple, and the preparation of the polymer fiber with a specific pore structure does not affect the complete shape of the fiber. Therefore, the method of the present invention will not limit the original application direction of polymer materials;

(3) The method for controlling the relaxation time of the present invention has a wide range of applications, and there are many types of adjustable organic hydrogen-containing molecular contrast agents, which can be used to regulate the relaxation time of hydrogen atoms in molecules containing long aliphatic chains.

Description of drawings

Figure 1. The polymer pore structure of the composite fiber;

Figure 2. Schematic diagram of the electrospinning device;

Fig. 3. the low-field nuclear magnetic resonance spectrometer test result of embodiment 1-4 product, polybutylene succinate and lauric acid;

Fig. 4. the relative crystallinity of the lauric acid loaded in the embodiment 1-4 product compared to the lauric acid bulk;

Fig. 5. the low-field nuclear magnetic resonance spectrometer test result of embodiment 5-8 product, polyethylene terephthalate and capric acid.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

Polybutylene succinate is dissolved in chloroform to form a solution A with a mass fraction of 60%, and lauric acid (dodecanoic acid) is dissolved in chloroform to form a solution B with a mass fraction of 75%. , Mix the two solutions of A and B at a mass ratio of 1:2 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 1mL/h, the distance between the spinneret and the collection device was 20cm, the spinneret was connected to a high voltage of 20kV, and the collection device was connected to a high voltage of -2kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 2

Polybutylene succinate is dissolved in trimethane to form a mass fraction of 40% A solution, and lauric acid (dodecanoic acid) is dissolved in trichloromethane to form a mass fraction of 80% B solution, Mix the two solutions of A and B at a mass ratio of 1:1 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 1mL/h, the distance between the spinneret and the collection device was 20cm, the spinneret was connected to a high voltage of 20kV, and the collection device was connected to a high voltage of -2kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 3

Polybutylene succinate is dissolved in trimethane to form the A solution that the mass fraction is 40%, and lauric acid (dodecanoic acid) is dissolved in the trichloromethane to form the B solution that the mass fraction is 60%, Mix the two solutions of A and B at a mass ratio of 1:1 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 1mL/h, the distance between the spinneret and the collection device was 20cm, the spinneret was connected to a high voltage of 20kV, and the collection device was connected to a high voltage of -2kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 4

Polybutylene succinate is dissolved in trimethane to form a mass fraction of 40% A solution, and lauric acid (dodecanoic acid) is dissolved in trichloromethane to form a mass fraction of 40% B solution, Mix the two solutions of A and B at a mass ratio of 1:1 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 1mL/h, the distance between the spinneret and the collection device was 20cm, the spinneret was connected to a high voltage of 20kV, and the collection device was connected to a high voltage of -2kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

In order to illustrate the effectiveness of the method and process of the present invention, the T2 relaxation time of the products of Examples 1-4 was measured by a low-field nuclear magnetic resonance spectrometer, and the results are shown in FIG. 3 . The following conclusions can be drawn by Fig. 3: (a) the relaxation time of polybutylene succinate is not within the test range, and all information comes from lauric acid; (b) the hydrogen atoms contained in lauric acid show There are two main relaxation times, the first one is at 535ms and the second one is at 283ms; (c) when lauric acid is loaded in the pores of polybutylene succinate fiber, the hydrogen atoms contained in it relax The peak shape of the relaxation time remains unchanged, but the relaxation time is continuously adjustable under different processing techniques. It shows that the loading of lauric acid in polybutylene succinate fiber does not change the type and relative quantity of hydrogen atoms contained in lauric acid, but it will effectively reduce the relaxation time of hydrogen atoms contained in it.

In order to illustrate the limited situation of lauric acid in polybutylene succinate, the relative crystallinity of lauric acid in the composite fiber of the product of Example 1-4 is measured by differential scanning calorimeter to its body, and the results are as shown in Fig. 4. As can be seen from Fig. 4, owing to be relative to the relative crystallinity of lauric acid body, so the numerical value of lauric acid is 100%, and the product in embodiment 1-4, wherein the relative crystallinity of lauric acid of loading is all less than 100% %, and the range of decline of the product of Example 4 is the largest. The crystallization difficulty of materials in confined spaces increases, and the decrease in crystallinity has been confirmed by a large number of studies (see Lipeng Han et al. IOP Conference Series: Materials Science and Engineering, 2017, 182, 012010). From the results of relative crystallinity, it can be seen that Example 4 has the highest degree of restriction among Examples 1-4, and correspondingly, the relaxation time of lauric acid in the product of Example 4 has the largest decrease compared with the bulk relaxation time of lauric acid .

Example 5

Polyethylene terephthalate is dissolved in the mixed solution of dichloromethane:trifluoroacetic acid=2:1 (mass ratio) to form A solution with a mass fraction of 45%, and decanoic acid (decanoic acid) Dissolve in tetrahydrofuran to form B solution with a mass fraction of 75%, and mix A and B solutions at a mass ratio of 1:2 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 0.5mL/h, the distance between the spinneret and the collection device was 15cm, the spinneret was connected to a high voltage of 16kV, and the collection device was connected to a high voltage of -4kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 6

Polyethylene terephthalate is dissolved in the mixed solution of dichloromethane:trifluoroacetic acid=2:1 (mass ratio) to form A solution with a mass fraction of 30%, and decanoic acid (decanoic acid) Dissolve in tetrahydrofuran to form a solution B with a mass fraction of 80%, and mix the two solutions A and B at a mass ratio of 1:1 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 0.5mL/h, the distance between the spinneret and the collection device was 15cm, the spinneret was connected to a high voltage of 16kV, and the collection device was connected to a high voltage of -4kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 7

Polyethylene terephthalate is dissolved in the mixed solution of dichloromethane:trifluoroacetic acid=2:1 (mass ratio) to form A solution with a mass fraction of 30%, and decanoic acid (decanoic acid) Dissolve in tetrahydrofuran to form a B solution with a mass fraction of 60%, and mix the two solutions A and B at a mass ratio of 1:1 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 0.5mL/h, the distance between the spinneret and the collection device was 15cm, the spinneret was connected to a high voltage of 16kV, and the collection device was connected to a high voltage of -4kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 8

Polyethylene terephthalate is dissolved in the mixed solution of dichloromethane:trifluoroacetic acid=2:1 (mass ratio) to form A solution with a mass fraction of 30%, and decanoic acid (decanoic acid) Dissolve in tetrahydrofuran to form B solution with a mass fraction of 40%, and mix A and B solutions at a mass ratio of 1:1 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 0.5mL/h, the distance between the spinneret and the collection device was 15cm, the spinneret was connected to a high voltage of 16kV, and the collection device was connected to a high voltage of -4kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

In order to illustrate the universal applicability of the method and process of the present invention, the T2 relaxation time of the products of Examples 5-8 was measured by a low-field nuclear magnetic resonance spectrometer, and the test results are shown in FIG. 5 . From Fig. 5, following conclusions can be drawn: (a) the relaxation time of polyethylene terephthalate is not within the test range, and all information comes from capric acid; the hydrogen atom contained in capric acid shows 2 There are three main relaxation times, the first one is at 503ms, the second one is at 243ms; similar to the results in Fig. 3, the capric acid loaded in polyethylene terephthalate fibers contains hydrogen atoms The relaxation time is effectively reduced, which can be adjusted from 50ms to 150ms. The test results of Examples 1-4 (loaded dodecanoic acid) and Examples 5-8 (loaded decanoic acid) show that the method of the present invention is generally applicable to the regulation of hydrogen atom relaxation time in long-chain fatty acids/alcohols/esters .

Example 9

Dissolve polyvinyl alcohol in water to form a solution A with a mass fraction of 5%, and dissolve glyceryl monostearate in tetrahydrofuran to form a solution B with a mass fraction of 60%. The two solutions A and B are mixed at a ratio of 1:1 The mass ratio is mixed to obtain a spinning solution.

The solution is electrospun with the following parameters, the liquid supply device supply rate is 0.1mL/h, the distance between the spinneret and the collection device is 50cm, the spinneret is connected to a high voltage of 50kV, and the collection device is connected to a high voltage of -1kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 10

Styrene-butadiene-styrene block copolymer is dissolved in tetrahydrofuran to form a solution A with a mass fraction of 40%, and n-pentadecanol is dissolved in acetone to form a solution B with a mass fraction of 60%. The two solutions of B and B are mixed at a mass ratio of 2:3 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 5mL/h, the distance between the spinneret and the collection device was 30cm, the spinneret was connected to a high voltage of 40kV, and the collection device was connected to a high voltage of -20kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 11

Dissolve L/D-lactic acid random copolymer in dichloromethane to form A solution with a mass fraction of 24%, and dissolve sucrose caprate in N,N-dimethylacetamide to form a mass fraction of 90% The B solution, the two solutions A and B are mixed at a mass ratio of 1:1 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 5mL/h, the distance between the spinneret and the collection device was 30cm, the spinneret was connected to a high voltage of 10kV, and the collection device was connected to a high voltage of -50kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 12

Dissolve L/D-lactic acid random copolymer in dichloromethane to form A solution with a mass fraction of 24%, and dissolve sucrose caprate in N,N-dimethylacetamide to form a mass fraction of 50% The B solution, the two solutions A and B are mixed at a mass ratio of 1:1 to obtain a spinning solution.

The solution was electrospun with the following parameters, the liquid supply rate of the liquid supply device was 5mL/h, the distance between the spinneret and the collection device was 30cm, the spinneret was connected to a high voltage of 10kV, and the collection device was connected to a high voltage of -50kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Example 13

Dissolve cellulose acetate in N,N-dimethylacetamide to form a solution A with a mass fraction of 10%, and dissolve decyl caprate in toluene to form a solution B with a mass fraction of 20%. The two solutions were mixed at a mass ratio of 3:2 to obtain a spinning solution.

The solution is electrospun with the following parameters, the liquid supply device supply rate is 10mL/h, the distance between the spinneret and the collection device is 25cm, the spinneret is connected to a high voltage of 25kV, and the collection device is connected to a high voltage of -10kV.

The collected composite fiber product is dried, immersed in water, and the air in the fiber is exhausted.

Claims (8)

1. The preparation method of the composite material with controllable relaxation time is characterized by comprising the following preparation steps:

(S1) preparing a spinning solution: dissolving a polymer material in a solvent to form a polymer solution, and dissolving an organic hydrogen-containing molecular contrast agent in the solvent to form a contrast agent solution;

(S2) mixing the two solutions for electrostatic spinning;

(S3) drying the collected composite fiber product, immersing the product in water, and exhausting air in the fiber to obtain a composite material with controllable relaxation time;

the organic hydrogen-containing molecular contrast agent in the step (S1) is one or more than two of long-chain fatty monoacid, long-chain fatty monoalcohol, monoacid monoalcohol long-chain fatty ester and monoacid polyalcohol long-chain fatty ester;

the long-chain fatty monoacid is fatty monoacid with carbon number of 8-24; the long-chain fatty monohydric alcohol is fatty monohydric alcohol with carbon number of 8-16; the monoacid monohydric alcohol long-chain fatty ester is an ester with carbon number of 8-28 formed by long-chain fatty monohydric acid and long-chain fatty monohydric alcohol; the monoacid polyol long-chain fatty ester is an ester compound formed by glycerol, sucrose, glucose, fructose and long-chain fatty monoacid with the carbon number of 8-18.

2. A method of preparing a composite material with controlled relaxation time according to claim 1, wherein: the polymer material in the step (S1) is one or more than two of a polyester polymer and a derivative thereof, a polyolefin polymer and a derivative thereof, a polyamide polymer and a derivative thereof, cellulose and a derivative thereof, chitosan, polyoxymethylene, hyaluronic acid, fibrin, silk fibroin, a blend copolymer of the above polymers and a block copolymer.

3. A method of preparing a composite material with controlled relaxation time according to claim 2, wherein:

the polyester polymer and the derivative thereof are at least one of polyglycolide, polylactic acid, polycaprolactone, polyglycolic acid, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate and polycarbonate; the polyolefin polymer and the derivative thereof are at least one of polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyisoprene, polyvinylpyrrolidone, polyvinyl alcohol and polyacrylonitrile; the polyamide polymer and the derivative thereof are at least one of nylon 6, nylon 66, nylon 610 and nylon 1212; the cellulose and the derivative thereof are at least one of cellulose acetate, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose; the blending copolymer and the block copolymer are at least one of a L-polylactic acid copolymer, a polyethylene glycol-polylactic acid block copolymer, a polyethylene glycol-polycaprolactone block copolymer, a polyethylene glycol-polyvinylpyrrolidone block copolymer, a polystyrene-polybutadiene block copolymer, a styrene-butadiene-styrene triblock copolymer, a polystyrene-poly (ethylene-butylene) -polystyrene block copolymer, a styrene-isoprene/butadiene-styrene block copolymer and a polystyrene-polybutadiene-polystyrene block copolymer.

4. A method of preparing a composite material with controlled relaxation time according to claim 1, wherein:

the solvent in the step (S1) is one or more of pentane, N-hexane, methylcyclohexane, dichloromethane, chloroform, dichloroethane, tetrachloroethane, carbon tetrachloride, methyl acrylate, tetrahydrofuran, methyltetrahydrofuran, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, diethyl ether, petroleum ether, acetone, formic acid, acetic acid, trifluoroacetic acid, hexafluoroisopropanol, xylene, toluene, phenol, chlorobenzene, nitrobenzene, cresol, anisole, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and amyl alcohol.

5. A method of preparing a composite material with controlled relaxation time according to claim 1, wherein: the concentration of the polymer solution in the step (S1) is 5-45%, and the concentration of the contrast agent solution is 20-90%.

6. A method of preparing a composite material with controlled relaxation time according to claim 1, wherein: the electrospinning conditions in the step (S2) are as follows: the liquid supply rate of the liquid supply device is 0.1-10 mL/h, the distance between the spinneret and the collecting device is 5-50 cm, the high voltage is 10-50 kV at the spinneret, and the high voltage is 0-50 kV at the collecting device.

7. A composite material with a controlled relaxation time prepared by the method of any one of claims 1 to 6.

8. The use of a controlled relaxation time composite material according to claim 7, wherein (1) MRI signals are provided to the polymer material; (2) Providing a sample having a standard relaxation time for device calibration; (3) As an implant material with standard MRI signal intensity for MRI signal calibration in humans.

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