CN113603993A

CN113603993A - Preparation method of self-healing polymer-nano composite material

Info

Publication number: CN113603993A
Application number: CN202110790545.7A
Authority: CN
Inventors: 陈苏; 翟江; 刘畅; 李阁
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2021-07-13
Filing date: 2021-07-13
Publication date: 2021-11-05
Anticipated expiration: 2041-07-13
Also published as: CN113603993B

Abstract

The invention relates to a preparation method of a self-healing polymer-nano composite material, which comprises the steps of generating carbon quantum dots on a polymer substrate in situ, and extruding by a double screw to form the self-healing polymer-nano composite material. The composite material obtained by the method has excellent fluorescence, good mechanical strength and self-healing performance. Compared with the traditional flexible self-healing polymer, the self-healing behavior of the hard polymer is realized, and the application range of the polymer material is greatly expanded. Meanwhile, the preparation method is simple and easy to implement, and has strong popularization and application values.

Description

Preparation method of self-healing polymer-nano composite material

Technical Field

The invention relates to a preparation method of a polymer-nano composite material with excellent fluorescence, good mechanical strength and self-healing performance, and the self-healing material can be widely used for various engineering materials and prolongs the service life of the engineering materials. Meanwhile, the preparation method is simple and feasible and has innovation.

Technical Field

Nowadays, various high molecular polymer materials are being widely used in industrial products in our daily lives. However, a major disadvantage is that these engineering materials gradually age and degrade over time. Thus, self-healing polymer materials have attracted considerable attention from researchers. Many self-healing polymers have also been successfully prepared. However, at present, the reported self-healing polymers are flexible polymer materials prepared by polymerization reaction of monomers, and the flexible polymer self-healing materials have low strength and good ductility, and can be widely applied to electronic skins, photoelectric device displays and medical fields. Meanwhile, the traditional engineering plastics and engineering polymer materials need to have certain tensile strength, such as common polypropylene plastics, rubber tires, polyester materials and the like, and the self-healing of the traditional hard polymer materials is realized, so that the service life of the materials can be prolonged, the production cost is reduced, and the production efficiency is improved. And few researches on the self-healing material are reported at present. Based on the self-healing performance, the research on the self-healing performance of the hard engineering polymer material is carried out, and the method has great practical significance.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a preparation method of a self-healing polymer-nano composite material, and the self-healing polymer-nano composite material prepared by the method has excellent fluorescence and good mechanical strength, more importantly, the material achieves self-healing performance and is a hard self-healing polymer composite material different from the traditional flexible self-healing polymer. The added value of the material is greatly improved, and the method can be widely applied to the field of engineering materials.

The technical scheme of the invention is as follows: a preparation method of a self-healing polymer-nanometer material is characterized by comprising the following steps: carbon quantum dots are generated in situ on the polymer substrate, and the self-healing polymer-nano composite material is formed by double-screw extrusion. The method comprises the following specific steps:

the method comprises the following steps: compounding ingredients, namely fully and uniformly mixing the carbon quantum dot precursor powder with the polymer base material, or fully and uniformly mixing the carbon quantum dot precursor powder with the carbon nitride and the polymer base material;

step two: and extruding and pelletizing, namely enabling the fully mixed composite material to pass through a double-screw extruder to generate carbon quantum dots in situ, and forming the self-healing polymer-nano composite material through a pelletizer.

Preferably, the carbon quantum dot precursor powder is sodium alginate-urea, citric acid-urea or citrate-urea; wherein the mass fraction of urea in the carbon quantum dot precursor powder is 50-75%.

Preferably, when the carbon quantum dot precursor powder is mixed with the polymer base material, carbon nitride is added, so that the healing performance of the self-healing polymer-nano composite material is improved to a certain extent.

Preferably, the polymer substrate is polymethyl methacrylate or polyurethane.

Preferably, the mass ratio of the carbon quantum dot precursor powder to the polymer base material is 0.01-0.5; the mass ratio of the carbon nitride to the polymer base material is 0.01-0.1.

The reaction temperature of the double-screw extruder is preferably 180-230 ℃.

Has the advantages that:

1. the method can be used as a simple and rapid method for preparing the carbon quantum dots, is simpler and more convenient compared with the traditional preparation method, and simultaneously realizes large-scale continuous preparation of the carbon quantum dots. The coupling with the polymer maintains the fluorescence property of the carbon quantum dots, and is easy for subsequent processing.

2. The invention is innovative in that the carbon nitride is added into the polymer/carbon quantum dot self-healing composite material, and the end group of the carbon nitride is easier to form hydrogen bonds and covalent bonds, thereby further improving the self-healing performance of the material.

3. The self-healing performance of the hard polymer material is realized by a simple preparation method, and the original mechanical property of the polymer is maintained, and meanwhile, the self-healing capacity of the hard polymer material is endowed. The application field of polymer products is enlarged, and the added value of the products is improved.

Drawings

Fig. 1 is a diagram of an embodiment of the self-healing polymer-nanomaterial of example 1, wherein a is the pelletized particles and b is the injection molded sample morphology.

Fig. 2 shows the ir spectra of the self-healing polymer-nanomaterial of polymer substrate polymethylmethacrylate (a), example 1(b) and example 5 (c).

FIG. 3 is a characterization of healing efficiency (tensile strength of material tested by universal testing machine) of the self-healing polymer-nanomaterial of example 5, where a is the original strength of the material and b is the strength of the material after healing.

The specific implementation mode is as follows:

example 1:

1. weighing citric acid and urea according to the mass ratio of 1:2, namely precursor powder of the carbon quantum dots, and uniformly mixing the precursor powder of the carbon quantum dots and the polymethyl methacrylate in different proportions (the mass ratio of the precursor of the carbon quantum dots to the polymethyl methacrylate is 0.02, 0.1 and 0.5 respectively).

2. And putting the uniformly mixed component A into a double-screw extruder for melting and mixing. Wherein the reaction temperature of the twin-screw extruder was set to 200 ℃. The rotating speed of a main machine of the twin-screw is set to be 15r/min, and the speed of the feeder is set to be 10 r/min. And (3) after extrusion, bracing and cooling by adopting a water cooling mode, then feeding the material into a granulator for granulation, and setting the granulation speed to be parallel to the rotating speed of the screw to obtain carbon quantum dot/polymethyl methacrylate particles B (the infrared representation of the material is shown in B in the attached figure 2).

3. And (3) performing injection molding on the component B by using an injection machine (the appearance of the sample is shown as figure 1 (B)), breaking the sample in a liquid nitrogen cooling mode, immersing the sample in an ethanol solution (directly dissolving the composite material particles in ethanol) of the carbon quantum dots for several seconds, taking out the sample, and observing the self-healing phenomenon in a natural environment at normal temperature and normal pressure. The healing efficiency is characterized by the ratio of the tensile strength of the test material in the universal tester, both original and after healing.

Example 2:

1. sodium alginate and urea are weighed according to the mass ratio of 1:1, namely precursor powder of the carbon quantum dots is mixed with the polymethyl methacrylate uniformly according to the mass ratio of 0.1.

2. And putting the uniformly mixed component A into a double-screw extruder for melting and mixing. Wherein the reaction temperature of the twin-screw extruder was set to 230 ℃. The rotating speed of the double-screw main machine is set to be 15r/min, and the speed of the feeder is set to be 10 r/min. And (3) after extrusion, bracing and cooling are carried out in a water cooling mode, then the extruded material enters a granulator for granulation, and the granulation speed is set to be parallel to the rotating speed of the screw, so that carbon quantum dot/polymethyl methacrylate particles B are obtained.

3. And the component B is subjected to injection molding by an injection machine, a sample is fractured in a liquid nitrogen cooling mode, is immersed in an ethanol solution (the composite material particles are directly dissolved in ethanol) of the carbon quantum dots, is taken out after several seconds, and is observed in a natural environment at normal temperature and normal pressure to represent the self-healing performance.

Example 3:

1. weighing zinc citrate and urea according to the mass ratio of 1:2, namely precursor powder of the carbon quantum dots, and uniformly mixing the precursor powder with polymethyl methacrylate according to the mass ratio of 0.1.

2. And putting the uniformly mixed component A into a double-screw extruder for melting and mixing. Wherein the reaction temperature of the twin-screw extruder was set to 180 ℃. The rotating speed of the double-screw main machine is set to be 15r/min, and the speed of the feeder is set to be 10 r/min. And (3) after extrusion, bracing and cooling are carried out in a water cooling mode, then the extruded material enters a granulator for granulation, and the granulation speed is set to be parallel to the rotating speed of the screw, so that carbon quantum dot/polymethyl methacrylate particles B are obtained.

Example 4:

1. weighing citric acid and urea according to the mass ratio of 1:3, namely precursor powder of the carbon quantum dots, and uniformly mixing the precursor powder with the polymethyl methacrylate according to the mass ratio of 0.1.

2. And putting the uniformly mixed component A into a double-screw extruder for melting and mixing. Wherein the melt temperature of the twin-screw extruder was set at 200 ℃. The rotating speed of the double-screw main machine is set to be 15r/min, and the speed of the feeder is set to be 10 r/min. And (3) after extrusion, bracing and cooling are carried out in a water cooling mode, then the extruded material enters a granulator for granulation, and the granulation speed is set to be parallel to the rotating speed of the screw, so that carbon quantum dot/polymethyl methacrylate particles B are obtained.

3. The component B is formed by injection molding through an injection machine, a sample is broken in a liquid nitrogen cooling mode, the sample is immersed in an ethanol solution (the composite material particles are directly dissolved in ethanol) of a carbon quantum dot, and the pH value of a solution medium is adjusted by sulfuric acid and ammonia water respectively (the pH value is 3, and the pH value is 10). And taking out after several seconds, observing the self-healing phenomenon in a natural environment at normal temperature and normal pressure, and representing the self-healing performance.

Example 5:

1. weighing carbon nitride, citric acid and urea according to the mass ratio of 2:1:2, and uniformly mixing the mixture and the polymethyl methacrylate according to the mass ratio of 0.03.

3. And putting the uniformly mixed component A into a double-screw extruder for melting and mixing. Wherein the melt temperature of the twin-screw extruder was set at 200 ℃. The rotating speed of the double-screw main machine is set to be 15r/min, and the speed of the feeder is set to be 10 r/min. And (3) after extrusion, bracing and cooling by adopting a water cooling mode, then feeding the material into a granulator for granulation, and setting the granulation speed to be parallel to the rotating speed of a screw so as to obtain carbon nitride/carbon quantum dots/polymethyl methacrylate particles B (the infrared representation of the material is shown in the figure 2 c).

3. And (3) performing injection molding on the component B by using an injection machine, breaking a sample in a liquid nitrogen cooling mode, immersing the sample in an ethanol solution (directly dissolving the composite material particles in ethanol) of the carbon quantum dots for several seconds, taking out the sample, and observing the self-healing phenomenon in a natural environment at normal temperature and normal pressure to represent the self-healing performance (the performance test is shown in the attached figure 3).

Example 6:

1. weighing carbon nitride, citric acid and urea according to the mass ratio of 3:1:2, and uniformly mixing the mixture and the polymethyl methacrylate according to the mass ratio of 0.2.

3. And putting the uniformly mixed component A into a double-screw extruder for melting and mixing. Wherein the melt temperature of the twin-screw extruder was set at 200 ℃. The rotating speed of the double-screw main machine is set to be 15r/min, and the speed of the feeder is set to be 10 r/min. And (3) after extrusion, bracing and cooling by adopting a water cooling mode, then feeding the material into a granulator for granulation, and setting the granulation speed to be parallel to the rotating speed of the screw so as to obtain the carbon nitride/carbon quantum dots/polymethyl methacrylate particles B.

3. And the component B is subjected to injection molding by an injection machine, a sample is fractured in a liquid nitrogen cooling mode, the sample is taken out after being immersed in an ethanol solution (directly dissolving the composite material particles in ethanol) of the carbon quantum dots for several seconds, and the self-healing phenomenon is observed in a natural environment at normal temperature and normal pressure to represent the self-healing performance of the component B.

Example 7:

1. weighing carbon nitride, citric acid and urea according to the mass ratio of 3:1:2, and uniformly mixing the mixture and polyurethane according to the mass ratio of 0.2.

3. And putting the uniformly mixed component A into a double-screw extruder for melting and mixing. Wherein the melt temperature of the twin-screw extruder was set at 200 ℃. The rotating speed of the double-screw main machine is set to be 15r/min, and the speed of the feeder is set to be 10 r/min. And (3) bracing and cooling by adopting a water cooling mode after extrusion, then entering a granulator for granulation, and setting the granulation speed to be parallel to the rotating speed of the screw rod to obtain the carbon nitride/carbon quantum dots/polyurethane particles B.

Claims

1. A method for preparing a self-healing polymer-nano material, characterized in that: carbon quantum dots are generated in situ on a polymer base material, and a self-healing polymer-nano composite material is formed by twin-screw extrusion.

2. preparation method as claimed in claim 1, its concrete steps are as follows:

Step 1: compound ingredients, fully and uniformly mix the carbon quantum dot precursor powder and the polymer substrate, or fully and uniformly mix the carbon quantum dot precursor powder with carbon nitride and the polymer substrate;

Step 2: extruding and dicing, generating carbon quantum dots in situ through the fully mixed composite material through a twin-screw extruder, and forming a self-healing polymer-nano composite material through a granulator.

3. The preparation method according to claim 2, wherein: the carbon quantum dot precursor powder is sodium alginate-urea, citric acid-urea or citrate-urea; wherein the carbon quantum dot precursor powder The mass fraction of urea in the medium is 50% to 75%.

4. The preparation method of claim 2, wherein the polymer base material is polymethyl methacrylate or polyurethane.

5. The preparation method according to claim 2, wherein the mass ratio of the carbon quantum dot precursor powder and the polymer substrate is 0.01-0.5; the mass ratio of the carbon nitride and the polymer substrate is 0.01-0.1.

6 . The preparation method according to claim 2 , wherein the reaction temperature of the twin-screw extruder is 180° C. to 230° C. 7 .