阅读说明：本技术 一种DDM-GO@SiO2复合材料、制备方法及制备TPU的用途 (DDM-GO @ SiO2Composite material, preparation method and application of prepared TPU ) 是由 丁国新 台洪旭 张宏艳 程国君 孙晨枫 柏杨 万祥龙 王周锋 于 2021-08-09 设计创作，主要内容包括：本发明属于高分子材料技术领域,特别涉及一种DDM-GO@SiO-(2)复合材料,并进一步公开其制备方法,以及用于制备TPU的用途。本发明所述DDM-GO@SiO-(2)复合材料,以DDM对GO进行改性,并在DDM-GO颗粒表面原位生成SiO-(2),得到DDM-GO@SiO-(2)复合材料,有效解决了GO存在的易团聚以及热稳定性不足的问题。所述DDM-GO@SiO-(2)复合材料作为功能性填料加入至TPU弹性体有效改善了TPU材料的力学及紫外光屏蔽性能,可得到力学强度高及抗紫外线的TPU复合材料,扩宽了TPU材料的应用领域和性能。(The invention belongs to the technical field of high polymer materials, and particularly relates to DDM-GO @ SiO 2 Composite materials, and further a process for their preparation, and the use for the preparation of TPUs are disclosed. The invention relates to DDM-GO @ SiO 2 The composite material is prepared by modifying GO with DDM and generating SiO in situ on the surface of DDM-GO particles 2 Obtaining DDM-GO @ SiO 2 The composite material effectively solves the problems of easy agglomeration and insufficient thermal stability of GO. The DDM-GO @ SiO 2 The composite material is added into the TPU elastomer as a functional filler, so that the mechanical and ultraviolet shielding properties of the TPU material are effectively improved, the TPU composite material with high mechanical strength and ultraviolet resistance can be obtained,the application field and the performance of the TPU material are widened.)

1. DDM-GO @ SiO₂The preparation method of the composite material is characterized by comprising the following steps:

(1) adding water into GO for dispersion, adding 4, 4' -diaminodiphenylmethane (DDM) for uniform mixing, carrying out reaction at 88-98 ℃, and collecting reaction products to obtain DDM-GO particles;

(2) and adding water into the DDM-GO particles for dispersing, adding a surfactant and water glass, fully and uniformly mixing, adjusting the pH value of a feed liquid system to 7-8 to form gel, collecting a product, and drying to obtain the DDM-GO particle gel.

2. The DDM-GO @ SiO of claim 1₂The preparation method of the composite material is characterized in that in the step (1), the mass ratio of GO to DDM is 1: 1-5.

3. DDM-GO @ SiO as in claim 1 or 2₂The preparation method of the composite material is characterized in that in the step (2):

the water glass comprises at least one of potassium silicate water glass and sodium silicate water glass;

the mass ratio of the added amount of the water glass to the DDM-GO particles is 4-8: 1.

4. the DDM-GO @ SiO of claim 3₂The preparation method of the composite material is characterized in that the modulus of the water glass is 2.3-3.5.

5. DDM-GO @ SiO as in any of claims 1-4₂The preparation method of the composite material is characterized in that in the step (2):

the surfactant comprises at least one of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and hexadecyl trimethyl ammonium bromide;

the mass ratio of the added amount of the surfactant to the DDM-GO particles is 0.8-1.2: 2.5.

6. DDM-GO @ SiO obtainable by a process according to any of claims 1 to 5₂A composite material.

7. The DDM-GO @ SiO of claim 6₂Application of composite material in preparing DDM-GO @ SiO₂Use of a/TPU composite.

8. Preparation of DDM-GO @ SiO₂A method of preparing a/TPU composite, comprising combining the DDM-GO @ SiO of claim 6₂A step of mixing the composite material with the TPU elastomer in the presence of a solvent, and a step of collecting and drying the product.

9. Preparation of DDM-GO @ SiO as in claim 8₂Method for producing a TPU composite, characterized in that the DDM-GO @ SiO₂The mass ratio of the thermoplastic polyurethane elastomer to the TPU elastomer is 1-20: 1000.

10. DDM-GO @ SiO obtainable by the process of claim 8 or 9₂A TPU composite material.

Technical Field

The invention belongs to the technical field of high polymer materials, and particularly relates to DDM-GO @ SiO₂Composite materials, and further a process for their preparation, and the use for the preparation of TPUs are disclosed.

Background

Thermoplastic Polyurethane (TPU) is a thermoplastic TPU elastomer, which has both high elasticity of rubber and thermoplastic processability of thermoplastics, and as an elastomer, it can maintain good elasticity in a wide temperature range, and is widely used in the fields of electronics, automobiles, medicine, and the like, but the mechanical properties of conventional TPU materials are always weak items, and cannot meet target requirements in many applications. In the prior art, a nano composite material and TPU are mostly blended to improve the mechanical property of the TPU, so that a novel composite material with excellent mechanical property is obtained, and graphene oxide is a functional material capable of improving the performance of the TPU.

Graphene oxide (graphene oxide) is an oxide of graphene, and after oxidation, the graphene oxide has more active properties than graphene due to the increase of oxygen-containing functional groups thereon, and can improve properties of graphene itself through various reactions with the oxygen-containing functional groups. In recent years, Graphene Oxide (GO) has been actively studied in various fields with its excellent properties. However, the GO has larger surface energy and a plurality of polar groups such as hydroxyl groups, carboxyl groups and the like on the surface, so that the sheets of the GO are easy to agglomerate and not easy to disperse in practical application, and the insufficient thermal stability of the GO further limits the application.

Nano silicon dioxide (SiO)₂) The material is an inorganic chemical material, and has a plurality of unique properties such as small volume effect, quantum size effect and the like due to the superfine nanometer level and the size range of 1-100nm, and the mechanical strength and the heat resistance of the material can be obviously improved. Mixing nano silicon dioxide (SiO)₂) Load forms GO @ SiO on GO surface₂The nano composite material can not only improve the problem that GO is difficult to disperse, but also play a role in synergistic reinforcement in a polymer, so that the mechanical property of TPU can achieve an ideal effect. The GO sheet has excellent optical characteristics, and the conjugated and aromatic structure on the surface of the GO sheet can absorb ultraviolet rays to prevent the ultraviolet rays from transmitting; and SiO₂The organic light-emitting diode can better reflect ultraviolet rays when being introduced, and can play a role in cooperatively shielding ultraviolet rays when being used together with GO. Therefore, the development of the functional TPU composite material has positive significance for the wide and stable application of the TPU material.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to provide a DDM-GO @ SiO₂The composite material effectively overcomes the defects of easy agglomeration and insufficient thermal stability of GO;

the second technical problem to be solved by the invention is to provide a mechanical property enhanced and ultraviolet light shielding DDM-GO @ SiO₂A TPU composite material.

In order to solve the technical problem, the invention provides DDM-GO @ SiO₂The preparation method of the composite material comprises the following steps:

(1) adding water into GO for dispersion, adding 4, 4' -diaminodiphenylmethane (DDM) for uniform mixing, carrying out reaction at 88-98 ℃, and collecting reaction products to obtain DDM-GO particles;

(2) and adding water into the DDM-GO particles for dispersing, adding a surfactant and water glass, fully and uniformly mixing, adjusting the pH value of a feed liquid system to 7-8 to form gel, collecting a product, and drying to obtain the DDM-GO particle gel.

Specifically, in the step (1), the mass ratio of GO to DDM is 1: 1-5, preferably 1: 3.

preferably, in the step (1), the reaction temperature is 95 ℃.

Specifically, in the step (2):

the water glass comprises at least one of potassium silicate water glass and sodium silicate water glass;

the mass ratio of the added amount of the water glass to the DDM-GO particles is 4-8: 1.

preferably, the modulus of the water glass is 2.3 to 3.5.

Specifically, in the step (2):

the surfactant comprises at least one of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and hexadecyl trimethyl ammonium bromide;

the mass ratio of the added amount of the surfactant to the DDM-GO particles is 0.8-1.2: 2.5.

the invention also discloses DDM-GO @ SiO prepared by the method₂A composite material.

The invention also discloses the DDM-GO @ SiO₂Application of composite material in preparing DDM-GO @ SiO₂Use of a/TPU composite.

The invention also discloses a method for preparing DDM-GO @ SiO₂A method of preparing a/TPU composite comprising combining said DDM-GO @ SiO₂A step of mixing the composite material with the TPU elastomer in the presence of a solvent, and a step of collecting and drying the product.

In particular, the DDM-GO @ SiO₂The mass ratio of the thermoplastic polyurethane to the TPU is 1-20: 1000, preferably 5: 1000.

the invention also discloses DDM-GO @ SiO prepared by the method₂A TPU composite material.

The invention relates to DDM-GO @ SiO₂The composite material is prepared by modifying Graphene Oxide (GO) with 4, 4' -diaminodiphenylmethane (DDM) to obtain DDM-GO particles, and then generating silicon dioxide (SiO) on the surfaces of the DDM-GO particles in situ₂) Obtaining DDM-GO @ SiO₂The composite material improves the hydrophobicity of GO and solves the problem of agglomeration of GO in a TPU matrix; at the same time, DDMThe self is grafted to the GO surface as an amino modifier, so that the thermal stability of GO can be obviously improved, the problems of easy agglomeration and insufficient thermal stability of GO are effectively solved, and the thermal stability of the GO is improved₂The preparation method of the composite material is simple and easy to implement and is easy for industrial production.

The invention relates to DDM-GO @ SiO₂The composite material is applied to modification optimization of Thermoplastic Polyurethane (TPU) materials, and a functional filler DDM-GO @ SiO is introduced into a TPU elastomer₂By means of said DDM-GO @ SiO₂The composite material has good dispersibility and thermal stability, so that GO can better exert the modification effect, and nano SiO is used₂The high-performance TPU composite material has the advantages of light weight, high temperature resistance, corrosion resistance and the like, can be used as an excellent reinforcing material applied to a high polymer material to improve the mechanical and ultraviolet shielding performance of the high polymer material, effectively improves the mechanical performance and ultraviolet resistance of the TPU material, can be obtained, widens the application field and performance of the TPU material, and is DDM-GO @ SiO₂The preparation method of the TPU composite material is simple and easy to implement and is easy for industrial production.

Drawings

In order that the present disclosure may be more readily and clearly understood, the following detailed description of the present disclosure is provided in connection with specific embodiments thereof and the accompanying drawings, in which,

FIG. 1 shows DDM-GO @ SiO in preparation example 1₂Scanning electron micrographs of the composite;

FIG. 2 is a thermogravimetric plot of DDM-GO particles and GO material in different proportions in preparation examples 1 and 4-6.

Detailed Description

Preparation example 1

Adding weighed 0.5gGO into 300ml deionized water, ultrasonically dispersing for 20min, pouring GO dispersion liquid into a three-necked bottle, mechanically stirring for 10min at 95 ℃, adding 1.5g of DDM, refluxing for 10h, performing suction filtration while the GO is hot, washing for 3-5 times by using hot water, removing unreacted DDM, and placing a product obtained by suction filtration in a freeze drying box for drying to obtain the DDM-GO composite material.

Adding 0.5g of the DDM-GO composite material obtained in the previous step into 50ml of deionized waterMechanically stirring for 10min, adding 0.2g of surfactant sodium dodecyl benzene sulfonate, uniformly stirring, adding 3g of potassium silicate water glass with the modulus of 3.3, mechanically stirring for 10min, adding 10ml of HCl with the molar concentration of 1mol/L, keeping the pH value to be 7-8, standing for more than 30min to form gel, performing suction filtration, washing, and finally performing freeze drying to obtain DDM-GO @ SiO₂A composite material.

DDM-GO @ SiO solid described in this preparation example₂The scanning electron microscope image of the composite material is shown in the attached figure 1. It can be seen that after the GO is modified by DDM, the surface wrinkles are increased, and the lamellar layer is thinned, because the hexagonal carbon skeleton of GO is damaged by DDM serving as a reducing agent, and defects and loss of long-range ordering are introduced on the surface of the graphene sheet, so that the graphene sheet is wrinkled and bent. Also, it can be seen that the DDM-GO surface is loaded with a lot of attached SiO₂Particles of SiO₂No peeling off in the cleaning and purifying process, which shows that SiO₂The in-situ growth on the GO surface is grafted through chemical bonds, which shows that the DDM-GO @ SiO₂Was successfully prepared.

Preparation example 2

Adding weighed 0.5gGO into 300ml deionized water, ultrasonically dispersing for 20min, pouring GO dispersion liquid into a three-necked bottle, mechanically stirring for 10min at 88 ℃, adding 1.5g of DDM, refluxing for 10h, performing suction filtration while the GO is hot, washing for 3-5 times by using hot water, removing unreacted DDM, and placing a product obtained by suction filtration in a freeze drying box for drying to obtain the DDM-GO composite material.

Adding 0.5g of the obtained DDM-GO composite material into 50ml of deionized water, mechanically stirring for 10min, adding 0.2g of surfactant lauryl sodium sulfate, uniformly stirring, adding 3g of potassium silicate water glass with the modulus of 3.3, mechanically stirring for 10min, adding 10ml of HCl with the molar concentration of 1mol/L, keeping the pH value to be 7-8, standing for more than 30min to form gel, performing suction filtration, washing, and finally performing freeze drying to obtain the DDM-GO @ SiO₂A composite material.

Preparation example 3

Adding weighed 0.5gGO into 300ml deionized water, ultrasonically dispersing for 20min, pouring GO dispersion liquid into a three-necked bottle, mechanically stirring for 10min at 98 ℃, adding 1.5g of DDM, refluxing for 10h, performing suction filtration while the GO is hot, washing for 3-5 times by using hot water, removing unreacted DDM, and placing a product obtained by suction filtration in a freeze drying box for drying to obtain the DDM-GO composite material.

Adding 0.5g of the obtained DDM-GO composite material into 50ml of deionized water, mechanically stirring for 10min, adding 0.2g of surfactant cetyl trimethyl ammonium bromide, uniformly stirring, adding 3g of potassium silicate water glass with the modulus of 3.3, mechanically stirring for 10min, adding 10ml of HCl with the molar concentration of 1mol/L, finally keeping the pH value of 7-8, standing for more than 30min to form gel, performing suction filtration, washing, and finally performing freeze drying to obtain the DDM-GO @ SiO₂A composite material.

Preparation example 4

Adding weighed 0.5gGO into 300ml deionized water, ultrasonically dispersing for 20min, pouring GO dispersion liquid into a three-necked bottle, mechanically stirring for 10min at 95 ℃, adding 0.5g of DDM, refluxing for 10h, performing suction filtration while the GO is hot, washing for 3-5 times by using hot water, removing unreacted DDM, and placing a product obtained by suction filtration in a freeze drying box for drying to obtain the DDM-GO composite material.

Subsequent DDM-GO @ SiO₂The composite material was prepared as in preparation example 1.

Preparation example 5

Adding weighed 0.5gGO into 300ml deionized water, ultrasonically dispersing for 20min, pouring GO dispersion liquid into a three-necked bottle, mechanically stirring for 10min at 95 ℃, adding 1.0g of DDM, refluxing for 10h, performing suction filtration while the GO is hot, washing for 3-5 times by using hot water, removing unreacted DDM, and placing a product obtained by suction filtration in a freeze drying box for drying to obtain the DDM-GO composite material.

Subsequent DDM-GO @ SiO₂The composite material was prepared as in preparation example 1.

Preparation example 6

Adding weighed 0.5gGO into 300ml deionized water, ultrasonically dispersing for 20min, pouring GO dispersion liquid into a three-necked bottle, mechanically stirring for 10min at 95 ℃, adding 2.0g of DDM, refluxing for 10h, performing suction filtration while the GO is hot, washing for 3-5 times by using hot water, removing unreacted DDM, and placing a product obtained by suction filtration in a freeze drying box for drying to obtain the DDM-GO composite material.

Subsequent DDM-GO @ SiO₂The composite material was prepared as in preparation example 1.

The thermogravimetric curves of the DDM-GO particles prepared based on different proportions of materials in preparation 1 and 4-6 above are shown in FIG. 2, with GO as the control.

As shown in the result of FIG. 2, the thermogravimetric curves of the DDM-GO composite materials with different proportions, the TG curve of GO shows two platforms, the degradation at 25-110 ℃ is the volatilization of the water on the surface of GO, and the degradation at 180-240 ℃ is the oxidative decomposition of oxygen-containing groups such as GO surface-COOH, -OH, -O-and the like into CO₂Volatilization and degradation of small molecules. With the DDM: the increase of GO proportion, the thermal stability of DDM-GO is increased firstly and then reduced, and the ratio of GO to the thermal stability of DDM-GO is increased after that of GO: DDM ═ 1: the best thermal stability is achieved at 3. The improvement of the thermal stability is caused by the easy decomposed oxygen-containing group on the GO surface and the-NH on the DDM surface₂The reaction produces a stable amide bond. However, as the ratio of DDM increases, the thermal stability of DDM-GO decreases due to the fact that as the concentration of DDM increases, the reaction rate increases, and the molecular chain of DDM grafted on the GO surface covers part of the oxygen-containing groups, resulting in a decrease in grafting rate, thereby affecting the thermal stability.

Preparation example 7

The DDM-GO particles were obtained according to the method described in preparation example 1.

Adding 0.5g of the obtained DDM-GO composite material into 50ml of deionized water, mechanically stirring for 10min, adding 0.24g of surfactant sodium dodecyl benzene sulfonate, uniformly stirring, adding 2g of sodium silicate glass with the modulus of 2.3, mechanically stirring for 10min, adding 10ml of HCl with the molar concentration of 1mol/L, keeping the pH value to be 7-8, standing for more than 30min to form gel, performing suction filtration, washing, and finally performing freeze drying to obtain the DDM-GO @ SiO₂A composite material.

Preparation example 8

The DDM-GO particles were obtained according to the method described in preparation example 1.

Adding 0.5g of the obtained DDM-GO composite material into 50ml of deionized water, mechanically stirring for 10min, adding 0.16g of surfactant sodium dodecyl benzene sulfonate, uniformly stirring, adding 4g of sodium silicate glass with the modulus of 3.5, mechanically stirring for 10min, adding 10ml of sodium silicate glass with the molar concentration of 1molThe final pH value of HCl/L is 7-8, standing for more than 30min to form gel, performing suction filtration, washing, and finally performing freeze drying to obtain DDM-GO @ SiO₂A composite material.

Example 1

Weighing the DDM-GO @ SiO prepared in the preparation example 1₂Adding 0.01g of composite material into 100ml of Dimethylformamide (DMF), ultrasonically dispersing for 20min, then pouring into a three-neck bottle for heating in an oil bath at 80 ℃, then adding 10g of TPU elastomer, fully stirring for 4h, pouring into a mold, putting into a vacuum drying oven for drying at 80 ℃, and finally obtaining the DDM-GO @ SiO₂A TPU composite material.

Example 2

Taking the DDM-GO @ SiO prepared in the preparation example 1₂Adding 0.03g of composite material into 100ml of DMF, ultrasonically dispersing for 20min, then pouring into a three-necked bottle for heating in an oil bath at 80 ℃, then adding 10g of TPU elastomer, fully stirring for 4h, pouring into a mold, putting into a vacuum drying oven for drying at 80 ℃, and finally obtaining the DDM-GO @ SiO @₂A TPU composite material.

Example 3

Taking the DDM-GO @ SiO prepared in the preparation example 1₂Adding 0.05g of composite material into 100ml of DMF, performing ultrasonic dispersion for 20min, then pouring into a three-necked bottle for heating in an oil bath at 80 ℃, then adding 10g of TPU, fully stirring for 4h, pouring into a mold, putting into a vacuum drying oven for drying at 80 ℃, and finally obtaining the DDM-GO @ SiO₂A TPU composite material.

Example 4

Taking the DDM-GO @ SiO prepared in the preparation example 1₂Adding 0.10g of composite material into 100ml of DMF, ultrasonically dispersing for 20min, then pouring into a three-necked bottle for heating in an oil bath at 80 ℃, then adding 10g of TPU, fully stirring for 4h, pouring into a mold, putting into a vacuum drying oven for drying at 80 ℃, and finally obtaining the DDM-GO @ SiO₂A TPU composite material.

Example 5

Taking the DDM-GO @ SiO prepared in the preparation example 1₂Adding 0.20g of composite material into 100ml of DMF, ultrasonically dispersing for 20min, then pouring into a three-necked bottle for heating in an oil bath at 80 ℃, then adding 10g of TPU, fully stirring for 4h, pouring into a mold, putting into a vacuum drying oven for drying at 80 ℃, and finally obtaining the [email protected]₂A TPU composite material.

Comparative example 1

Weighing 10g of TPU, adding into 100ml of DMF, pouring into a three-neck flask, heating in an oil bath at 80 ℃, fully stirring for 4h, pouring into a mold, and putting into a vacuum drying oven to dry at 80 ℃ to finally obtain the TPU material.

Comparative example 2

Taking 0.05g of the DDM-GO composite material prepared in the preparation example 1, adding the DDM-GO composite material into 100ml of DMF, ultrasonically dispersing for 20min, then pouring the mixture into a three-necked bottle for heating in an oil bath at 80 ℃, then adding 10g of TPU, fully stirring for 4h, pouring the mixture into a mold, and putting the mold into a vacuum drying oven for drying at 80 ℃ to finally obtain the DDM-GO/TPU composite material.

Comparative example 3

Adding 0.2g of surfactant sodium dodecyl benzene sulfonate into 50ml of deionized water, stirring uniformly, adding 3g of potassium silicate water glass with the modulus of 3.3, mechanically stirring for 10min, adding 10ml of HCl with the molar concentration of 1mol/L, keeping the pH value of 7-8, standing for more than 30min to form gel, performing suction filtration, washing, and finally performing freeze drying to obtain SiO₂A material.

Taking the SiO prepared above₂Adding 0.05g of material into 100ml of DMF, ultrasonically dispersing for 20min, then pouring into a three-necked bottle for heating in an oil bath at 80 ℃, then adding 10g of TPU, fully stirring for 4h, pouring into a mold, putting into a vacuum drying oven for drying at 80 ℃, and finally obtaining SiO₂A TPU composite material.

Examples of the experiments

The TPU composites prepared in examples 1 to 5 and comparative examples 1 to 3 were subjected to tensile strength, elongation at break and ultraviolet light shielding property tests, and the results are shown in tables 1 and 2 below.

TABLE 1 mechanical Property results for TPU composites in examples 1-5 and comparative examples 1-3

TABLE 2 UV screening results of TPU composites in examples 1-5 and comparative examples 1-3

As can be seen from the results in Table 1 above, the DDM-GO @ SiO prepared according to the present invention compares to the TPU neat samples (comparative example 1), comparative examples 2-3₂The tensile strength and elongation at break of the TPU composite material with the filling amount of 0.5 wt% are improved. The remarkable improvement of the mechanical property can be attributed to DDM-GO @ SiO₂The mutual entanglement and diffusion of the DDM molecular chain on the surface and the TPU chain segment improve the interface adhesion and the DDM-GO @ SiO₂Uniform dispersion in the TPU matrix; at the same time, nano SiO₂The particle has large specific surface area and strong adsorbability, and can adsorb partial polymer molecular chains to the surface of the nano-particles to play a role of physical cross-linking points. However, with DDM-GO @ SiO₂The increase in the amount of filler, the excess filler clumps together, reduces the interaction force with the TPU, the formation of defects leads to stress concentrations, and this process may lead to a gradual decrease in tensile strength and elongation at break. Comparative example 3 Single addition of Nano SiO₂Particles due to untreated nano SiO₂The surface hydroxyl is numerous, the specific surface area is large, the surface energy is high, the material is hydrophilic, the material is difficult to uniformly disperse in a TPU matrix, the particle size is increased due to easy agglomeration, the internal stress of the material is concentrated, and defects are formed, so the mechanical property is relatively low. While the DDM-GO composite material with the content of 0.5% is added in the comparative example 2, the modified GO is added in a larger amount and is not easy to disperse, and the DDM-GO @ SiO is also shown₂The influence of the addition amount is large.

As can be seen from the results in Table 2 above, the DDM-GO @ SiO prepared according to the present invention compares to the TPU neat samples (comparative example 1), comparative examples 2-3₂As the filling amount is increased, the ultraviolet shielding efficiency is obviously improved. The reason for this is that the uv shielding efficiency is improved because GO sheets have excellent optical characteristics, conjugated and aromatic structures exist on the surface thereof to absorb uv rays to prevent transmission of uv rays, and SiO is present on the surface thereof₂The light-emitting diode can better reflect ultraviolet light by introducing, and can play a role in cooperatively shielding ultraviolet light by combining with GO.The lower UV shielding effectiveness of comparative examples 2, 3 also show that DDM-GO @ SiO₂Excellent ultraviolet shielding performance.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.