An underwater self-repairable high tensile elastomer and a method for preparing the same

Abstract

The application discloses an underwater self-repairable high tensile elastomer and a preparation method thereof, and belongs to the field of elastomer preparation. The application aims at solving the problems that the existing self-repairable materials cannot be efficiently self-repaired in a severe underwater environment, cannot maintain the self-repairing efficiency and tensile rate of the materials, and cannot enhance the mechanical properties of the materials. The underwater self-repairable high tensile elastomer is prepared from methyl methacrylate, ethyl acrylate and n-butyl esterified ethyl cellulose. The method comprises the following steps: 1, preparing n-butyl esterified ethyl cellulose; 2, mixing methyl methacrylate and ethyl acrylate; 3, adding the n-butyl esterified ethyl cellulose and dissolving; and 4, ultraviolet curing. The application is used for the underwater self-repairable high tensile elastomer and the preparation thereof.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of elastomer preparation. BACKGROUND

[0002] Self-healing materials are a class of intelligent materials that can automatically repair their original performance after suffering external damage. Due to the self-healing ability, the service life of the product can be effectively prolonged, and the reliability of the material can be improved, which has attracted widespread attention in the research field in the past few decades. Self-repairing refers to the ability to self-repair when mechanically damaged. Self-healing materials repair cracks by changing chemical bonds or releasing and polymerizing self-healing monomers stored in the material, thereby maintaining the integrity of the matrix structure. Compared with traditional materials, self-healing materials have excellent performance and a wider range of use environments.

[0003] Considering the long-term use of self-healing polymers, high humidity conditions or even underwater conditions are inevitable, therefore, the stability of self-healing polymers under water has become one of the necessary properties. However, most of the existing reversible self-healing materials are not stable under harsh humid conditions, because their reversible bonds have limitations in the self-healing process. Most of the current reversible self-healing materials are based on dynamic bonds, such as metal-ligand coordination, hydrogen bonding, ionic interaction, etc. Most of these dynamic bonds are unstable in water and are disturbed in various ways, and then the self-healing material will swell and lose its self-healing ability. Therefore, it is still challenging to achieve self-repairing under harsh conditions, such as underwater, seawater or strong acid / strong base conditions. At the same time, there is a trade-off between self-healing and the strength of the material and the self-repairing efficiency. Generally, stronger physical cross-linking will provide harder and more robust material performance, but due to the presence of fewer rearrangement networks on the damaged surface, the self-repairing efficiency will be reduced, and the stretchability based on the nature of the material will also be restricted. In this conventional design, it is difficult to achieve a balance between the strength of the material and the self-repairing efficiency and stretchability of the material, therefore, how to enhance the mechanical properties of the material while losing less self-repairing efficiency and stretchability of the material has been a challenge and a problem for self-healing materials. SUMMARY

[0004] The present application aims to solve the problem that existing self-repairing materials cannot efficiently self-heal in harsh underwater environments, cannot maintain the self-repairing efficiency and stretchability of the material while enhancing the mechanical properties of the material, and further provides a high-stretch elastomer that can self-repair underwater and a preparation method thereof.

[0005] A high-stretch elastomer that can self-repair underwater is prepared from methyl methacrylate, ethyl acrylate and n-butylated ethyl cellulose.

[0006] A preparation method of a high-stretch elastomer that can self-repair underwater is as follows:

[0007] I. n-butyric acid esterification of ethyl cellulose, then drying, to obtain n-butyric acid esterification of ethyl cellulose;

[0008] II. Methyl methacrylate and ethyl acrylate are mixed uniformly to obtain mixture A;

[0009] III. n-butyric acid esterification of ethyl cellulose is added to mixture A to dissolve, to obtain mixture B;

[0010] IV. Mixture B is subjected to ultraviolet curing, that is, the preparation method of the underwater self-repairable high tensile elastomer is completed.

[0011] The beneficial effects of the present application are:

[0012] The present application simultaneously utilizes modification of plant fiber derivatives, ethyl acrylate and methyl methacrylate random copolymer composite, wherein the ethyl cellulose is esterified by n-butyric acid, and the compatibility of the ethyl cellulose with ethyl acrylate and methyl methacrylate is good, which effectively improves the mechanical properties of the polymer material, and makes the material maintain the self-repair efficiency and tensile rate, and realizes high-efficiency self-repair in various harsh water environments.

[0013] The material is prepared by using light curing process, through random copolymerization of hard segment methyl methacrylate (MMA) and soft segment ethyl acrylate (EA), and formation of polymer network with n-butyric acid esterification of ethyl cellulose (BEEC). The electronegative oxygen atom on the ester group of the elastic material, the electro-positive and the carbon chain provide the healing ability of the material, wherein the Debye force has high density and excellent stability in harsh water environment. In addition, the balance between mechanical strength and self-healing ability is related to the behavior of the polymer. Improving the mechanical strength of a single high molecular material means increasing the intermolecular interaction force, which leads to the decrease of the migration ability of the polymer chain. Therefore, the present application uses the rigid six-membered ring of ethyl cellulose to increase the mechanical strength, and the natural structure of cellulose leads to a significant increase in the mechanical strength of the composite material after adding a small amount of ethyl cellulose. The esterification modification of ethyl cellulose can prevent the self-aggregation of cellulose through hydrogen bonds, thereby providing a rigid skeleton for the material, and enhancing the interaction and miscibility of ethyl cellulose with the polymer chain segment. The addition of BEEC also leads to loose accumulation of the polymer chain segment. This material forms smaller domains, thereby ensuring the flowability of the polymer chain segment. Therefore, it retains the self-healing ability and high tensile properties of the self-healing material. Since the polymer chain and the modified ethyl cellulose both have hydrophobic structure and chemical inertness, the material is not affected by the harsh underwater environment, and exhibits high self-healing ability in various harsh underwater environments.

[0014] The preparation method of the present application is simple, and can be used for large-size material preparation, and the mechanical properties can be adjusted by changing the proportion of cellulose addition. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Infrared spectra of n-butyl esterified ethyl cellulose prepared in step one of the example and ethyl acrylate described in step two;

[0016] Figure 2 Infrared spectra of n-butyl esterified ethyl cellulose prepared in step one of the example and ethyl acrylate described in step two; 1 HNMR spectra, 1 is ethyl cellulose, 2 is cellulose after n-butyl esterification;

[0017] Figure 3 Mechanical tensile curve and elastic modulus comparison chart of elastomers prepared in examples one to two and comparative experiments, a is the mechanical tensile curve, b is the elastic modulus;

[0018] Figure 4 Mechanical tensile curve and self-repairing efficiency comparison chart of the underwater self-repairing high tensile elastomer prepared in example one after self-repairing for 24 hours in different environments, a is the mechanical tensile curve, b is the self-repairing efficiency;

[0019] Figure 5 Transmittance comparison chart of elastomers prepared in example one and comparative experiments, a is P(EA-co-MMA)-0, b is P(EA-co-MMA)-3; from the chart, it can be seen that P(EA-co-MMA)-3 and P(EA-co-MMA)-0 have similar high transmittance higher than 80%;

[0020] Figure 6 SEM images of elastomers prepared in example one and comparative experiments, a is P(EA-co-MMA)-0, b is P(EA-co-MMA)-3;

[0021] Figure 7 Spectrum chart of small-angle scattering (SAXS) test of elastomers prepared in example one and comparative experiments, a is P(EA-co-MMA)-0, b is P(EA-co-MMA)-3. DETAILED DESCRIPTION

[0022] Specific embodiment one: the embodiment is an underwater self-repairing high tensile elastomer, which is prepared from methyl methacrylate, ethyl acrylate and n-butyl esterified ethyl cellulose.

[0023] The beneficial effects of the embodiment are:

[0024] The embodiment simultaneously utilizes the modification of plant fiber derivatives, ethyl cellulose, and the random copolymerization of ethyl acrylate and methyl methacrylate. After the butyration of ethyl cellulose, its compatibility with ethyl acrylate and methyl methacrylate is better, effectively improving the mechanical properties of the polymer material, and making it maintain the self-repair efficiency and tensile rate of the material, and achieving high-efficiency self-repair in various harsh water environments.

[0025] The material is prepared by using a photocuring process, through the random copolymerization of hard segment methyl methacrylate (MMA) and soft segment ethyl acrylate (EA), and forms a polymer network with butyrate-esterified ethyl cellulose (BEEC). The electropositive oxygen atoms on the ester groups of the elastic material and the Debye force between the electropositive carbon chains provide the healing ability of the material, where the Debye force has high density and excellent stability in harsh water environments. In addition, the balance between mechanical strength and self-healing ability is related to the behavior of the polymer. Improving the mechanical strength of a single high molecular material means increasing the intermolecular interaction force, which leads to a decrease in the migration ability of the polymer chain. Therefore, the embodiment uses the rigid six-membered ring of ethyl cellulose to increase the mechanical strength, and the natural structure of cellulose leads to a significant increase in the mechanical strength of the composite material after adding a small amount of ethyl cellulose. The esterification modification of ethyl cellulose can prevent the self-aggregation of cellulose through hydrogen bonds, thereby providing a rigid skeleton for the material and enhancing the interaction and miscibility of ethyl cellulose with the polymer chain segment. The addition of BEEC also causes the polymer chain segment to be loosely packed. This material forms smaller domains, thereby ensuring the flowability of the polymer chain segment. Therefore, it retains the self-healing ability and high tensile properties of the self-healing material. Since both the polymer chain and the modified ethyl cellulose have hydrophobic structures and chemical inertness, the material is not affected by harsh underwater environments and exhibits high self-healing ability in various harsh underwater environments.

[0026] The preparation method of the embodiment is simple, can be used for large-size material preparation, and has adjustable mechanical properties by changing the proportion of cellulose addition.

[0027] Specific embodiment two: The difference between this embodiment and specific embodiment one is that the molar ratio of ethyl acrylate to methyl methacrylate is 1:(0.1-1). The others are the same as specific embodiment one.

[0028] Specific embodiment three: The difference between this embodiment and one of specific embodiments one or two is that the mass ratio of the total volume of methyl methacrylate and ethyl acrylate to the mass of butyrate-esterified ethyl cellulose is 10 mL:(0.1-0.5) g. The others are the same as specific embodiments one or two.

[0029] Specific embodiment four: A preparation method of a high-tensile elastomer capable of underwater self-repair, which is carried out according to the following steps:

[0030] I. Esterification of ethyl cellulose with n-butyric acid, and then drying to obtain n-butyric acid esterified ethyl cellulose;

[0031] II. Methyl methacrylate and ethyl acrylate are mixed uniformly to obtain mixture A;

[0032] III. The n-butyric acid esterified ethyl cellulose is added into the mixture A to dissolve, to obtain mixture B;

[0033] IV. The mixture B is subjected to ultraviolet curing, and the preparation method of the underwater self-repairable high tensile elastomer is completed.

[0034] Specific embodiment five: the difference between this embodiment and the specific embodiment four is that: in step I, the esterification of ethyl cellulose with n-butyric acid is carried out, specifically as follows: n-butyric acid and ethyl cellulose are mixed and reacted at room temperature for 12h-36h. The others are the same as the specific embodiment four.

[0035] Specific embodiment six: the difference between this embodiment and the specific embodiment four or five is that: the molar ratio of n-butyric acid to glucose unit of ethyl cellulose is 1:(0.1-1). The others are the same as the specific embodiment four or five.

[0036] Specific embodiment seven: the difference between this embodiment and the specific embodiment four to six is that: the molar ratio of ethyl acrylate to methyl methacrylate in step II is 1:(0.1-1). The others are the same as the specific embodiment four to six.

[0037] Specific embodiment eight: the difference between this embodiment and the specific embodiment four to seven is that: the volume ratio of the mixture A to the mass of the n-butyric acid esterified ethyl cellulose in step III is 10mL:(0.1-0.5)g. The others are the same as the specific embodiment four to seven.

[0038] Specific embodiment nine: the difference between this embodiment and the specific embodiment four to eight is that: the dissolving in step III is specifically carried out at a temperature of 20℃-60℃. The others are the same as the specific embodiment four to eight.

[0039] Specific embodiment ten: the difference between this embodiment and the specific embodiment four to nine is that: the ultraviolet curing in step IV is specifically carried out at a wavelength of 265nm-365nm and a power of 100w-500w for 0.5h-3h. The others are the same as the specific embodiment four to nine.

[0040] The beneficial effects of the present application are verified by the following examples:

[0041] Example one:

[0042] A preparation method of an underwater self-repairable high tensile elastomer, which is carried out according to the following steps:

[0043] I. At room temperature, n-butyric acid and ethyl cellulose are mixed and reacted for 24 h, and then dried to obtain n-butyrate-esterified ethyl cellulose;

[0044] The molar ratio of n-butyric acid to glucose units of ethyl cellulose is 1:1;

[0045] II. Methyl methacrylate and ethyl acrylate are uniformly mixed to obtain a mixture A;

[0046] The molar ratio of ethyl acrylate to methyl methacrylate is 7:3;

[0047] III. The n-butyrate-esterified ethyl cellulose is added to the mixture A and heated to dissolve at a temperature of 50°C to obtain a mixture B;

[0048] The volume ratio of the mixture A to the mass of the n-butyrate-esterified ethyl cellulose is 10 mL:0.3 g;

[0049] IV. The mixture B is added to a mold, then ultraviolet cured for 2 h under the condition of a wavelength of 365 nm and a power of 300 W, and finally demolded to obtain the underwater self-repairable high tensile elastomer.

[0050] Example 2: Different from example 1, the volume ratio of the mixture A to the mass of the n-butyrate-esterified ethyl cellulose in step III is 10 mL:0.2 g. The others are the same as example 1.

[0051] Comparative experiment: Different from example 1, step III is omitted. The others are the same as example 1.

[0052] According to the addition amount of the n-butyrate-esterified ethyl cellulose, the tensile elastomer prepared in the comparative experiment is named as P(EA-co-MMA)-0 (addition amount 0 g), the underwater self-repairable high tensile elastomer prepared in example 2 is named as P(EA-co-MMA)-2 (addition amount 0.2 g), and the underwater self-repairable high tensile elastomer prepared in example 1 is named as P(EA-co-MMA)-3 (addition amount 0.3 g); the n-butyrate-esterified ethyl cellulose is abbreviated as BEEC; the ethyl acrylate is abbreviated as EA; and the methyl methacrylate is abbreviated as MMA.

[0053] Figure 1The infrared spectrum of the n-butyl esterified ethyl cellulose prepared in step one of the example and the ethyl acrylate described in step two; from the figure, it can be seen that the ethyl cellulose has a long-chain polysaccharide structure of rigid six-membered ring, and the modified ethyl cellulose has a large number of ester groups similar to ethyl acrylate on the surface.

[0054] Figure 2 The infrared spectrum of the n-butyl esterified ethyl cellulose prepared in step one of the example and the ethyl acrylate described in step two; from the figure, it can be seen that the ethyl cellulose has a long-chain polysaccharide structure of rigid six-membered ring, and the modified ethyl cellulose has a large number of ester groups similar to ethyl acrylate on the surface. 1 H NMR spectrum, 1 is ethyl cellulose, 2 is cellulose after n-butyl esterification; Figure 2 It is also verified that the ethyl cellulose has a long-chain polysaccharide structure of rigid six-membered ring, and the modified ethyl cellulose has a large number of ester groups similar to ethyl acrylate on the surface. This is the main reason why cellulose and elastomer can be miscible and maintain high healing ability. At the same time, the structure and composition of the composite material can be seen, and the high content of ester groups in the composite material is an important condition for the uniform compounding of cellulose with high molecular materials.

[0055] The mechanical test was carried out under the condition that the test speed was 40 mm / min; Figure 3 The mechanical tensile curve and elastic modulus comparison diagram of the elastomer prepared in examples one to two and comparative experiment, a is the mechanical tensile curve, b is the elastic modulus; from the figure, it can be seen that due to the homogeneous compounding of cellulose and elastomer, the tensile property of the composite material does not decrease with the increase of the addition amount of BEEC, and the mechanical property is significantly improved. When BEEC is added to 0.3 g / 10 mL, the elastic modulus is increased by 4 times compared with the pure self-repairing matrix material, and the maximum tensile strength is increased by two times. The underwater self-repairing high tensile elastomer prepared in example one has a tensile strength of 1.07 MPa, an elastic modulus of 9.8±2.8 MPa, and a tensile rate of 3689%.

[0056] The underwater self-repairing high tensile elastomer prepared in example one was cut into two parts, then the two parts were gently re-contacted and placed in a dry environment or different water bodies, and the two damaged cutting surfaces spontaneously healed in different environments at room temperature. Without any external stimulus, the self-repairing efficiency is the ratio of the toughness recovery to the original toughness (the area under the stress-strain curve, due to the long tensile time, the mechanical decline point is defined as the failure point). Figure 4The mechanical tensile curves and self-healing efficiency of the underwater self-healing high tensile elastomer prepared in Example 1 after self-healing for 24 h in different environments, a is the mechanical tensile curve, b is the self-healing efficiency; as can be seen from the figure, the self-healing efficiency in 24 h dry environment is 92.3±9.5%; the self-healing efficiency in 24 h pure water is 91.2±6.1%; the self-healing efficiency in 24 h seawater (seawater sample from Bohai, China) is 87.4±8.8%; the self-healing efficiency in 24 h physiological saline (concentration 0.9wt%) is 88.8±4.2%; the self-healing efficiency in 24 h NaOH solution with pH=13 is 86.9±11.1%; the self-healing efficiency in 24 h HCl solution with pH=1 is 82.8±2.4%.

[0057] The transmittance test was performed on 1.5 mm thick P(EA-co-MMA)-0 and P(EA-co-MMA)-3; Figure 5 The transmittance comparison chart of the elastomers prepared in Example 1 and comparative experiments, a is P(EA-co-MMA)-0, b is P(EA-co-MMA)-3; as can be seen from the figure, P(EA-co-MMA)-3 and P(EA-co-MMA)-0 have similar high transmittance of more than 80%; the composite material has high light transmittance, the transmittance of 1.5 mm thick P(EA-co-MMA)-0 is 86.5%, and the transmittance of P(EA-co-MMA)-3 is 87.0%. It can be seen that after adding BEEC, the light transmittance does not decrease obviously, which is due to the good interface compatibility between the n-butyl ester modified cellulose and the synthetic polymer elastomer substrate.

[0058] Figure 6 The SEM images of the elastomers prepared in Example 1 and comparative experiments, a is P(EA-co-MMA)-0, b is P(EA-co-MMA)-3; the observation of P(EA-co-MMA) surface by SEM shows that the surface of P(EA-co-MMA)-3 modified by adding n-butyl acid cellulose is as flat as the surface of P(EA-co-MMA)-0, which indicates that the cellulose is uniformly dispersed in the synthetic polymer elastomer.

[0059] Figure 7The SAXS spectrum of the elastomers prepared in Example 1 and the comparative experiment is shown in Figure 8, a is P(EA-co-MMA)-0, and b is P(EA-co-MMA)-3. It can be found from the SAXS test of P(EA-co-MMA)-0 and P(EA-co-MMA)-3 that the SAXS curve of P(EA-co-MMA)-0 has no obvious ordered peak, indicating that P(EA-co-MMA)-0 is of disordered structure. P(EA-co-MMA)-3 also has no obvious ordered peak, indicating that P(EA-co-MMA)-3 is also disordered. It is found that the addition of BEEC does not affect the microstructure of the P(EA-co-MMA)-0 composite material, and the composite material is still in a disordered state, which can effectively ensure the migration of the molecular chain at room temperature, thereby ensuring the self-repairing ability of the composite material at room temperature.

Claims

1. An underwater self-repairable high tensile elastomer, characterized in that It is prepared from methyl methacrylate, ethyl acrylate and n-butyl esterified ethyl cellulose; The mass ratio of the total volume of methyl methacrylate and ethyl acrylate to n-butyl esterified ethyl cellulose is 10 mL:(0.1-0.5) g; The underwater self-repairing high tensile elastomer is prepared by the following steps: I. Esterification of ethyl cellulose with n-butyl acid, then drying to obtain n-butyl esterified ethyl cellulose; II. Mix methyl methacrylate and ethyl acrylate uniformly to obtain mixture A; III. Add n-butyl esterified ethyl cellulose to mixture A to dissolve to obtain mixture B; IV. Ultraviolet curing of mixture B, i.e. the preparation method of the underwater self-repairing high tensile elastomer is completed.

2. The underwater self-healing high tensile elastomer according to claim 1, characterized in that The molar ratio of ethyl acrylate to methyl methacrylate is 1:(0.1-1).

3. A process for preparing an underwater self-healing high-stretch elastomer according to claim 1, characterized in that It is prepared by the following steps: I. Esterification of ethyl cellulose with n-butyl acid, then drying to obtain n-butyl esterified ethyl cellulose; II. Mix methyl methacrylate and ethyl acrylate uniformly to obtain mixture A; III. Add n-butyl esterified ethyl cellulose to mixture A to dissolve to obtain mixture B; IV. Ultraviolet curing of mixture B, i.e. the preparation method of the underwater self-repairing high tensile elastomer is completed.

4. The process for preparing an underwater self-healing high-stretch elastomer according to claim 3, characterized in that In step I, the esterification of ethyl cellulose with n-butyl acid is carried out by the following steps: mix n-butyl acid and ethyl cellulose at room temperature and react for 12-36 h.

5. A process for the preparation of a high-stretch elastomer that is self-repairable underwater according to claim 4, characterized in that The molar ratio of n-butyl acid to glucose unit of ethyl cellulose is 1:(0.1-1).

6. The process for preparing an underwater self-healing high-stretch elastomer according to claim 3, characterized in that The molar ratio of ethyl acrylate to methyl methacrylate in step II is 1:(0.1-1).

7. The method for preparing a highly tensile elastomer capable of underwater self-healing according to claim 3, characterized in that... The mass ratio of the volume of mixture A to n-butyl esterified ethyl cellulose in step III is 10 mL:(0.1-0.5) g.

8. The method for preparing a highly tensile elastomer capable of underwater self-healing according to claim 3, characterized in that... The dissolving in step III is carried out at a temperature of 20-60°C.

9. The method for preparing a highly tensile elastomer capable of underwater self-healing according to claim 3, characterized in that... The ultraviolet curing in step IV is carried out at a wavelength of 265-365 nm and a power of 100-500 W for 0.5-3 h.

Images