Zinc suberate nanosheet as well as preparation method and application thereof

Abstract

The invention discloses a zinc suberate nanosheet as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing sodium suberate, zinc chloride and a solvent, stirring, heating, carrying out ultrasonic treatment, and carrying out solid-liquid separation. The zinc suberate nanosheet with better dispersing performance and higher crystallinity can be prepared by introducing an ultrasonic step in the reaction process of sodium suberate and zinc chloride, and when the zinc suberate nanosheet is used for preparing the polylactic acid film, the crystallinity of the polylactic acid film can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, in particular to a zinc suberate nanosheet and a preparation method and application thereof. Background Art

[0002] Aliphatic dicarboxylates can promote the formation of abundant β-crystals in some polymers, improving their crystallization rate, crystallization density, and crystallite size, and enhancing the transparency, impact resistance, toughness, and thermal properties of polymer products. Studies have shown that barium glutarate, calcium suberate, and zinc suberate are the most effective dicarboxylates for nucleating β-crystals in polypropylene. For organic nucleating agents such as fatty acid metal salts, for example, the introduction of calcium and zinc suberate provides a large number of nucleation sites for polypropylene, inducing crystallization.

[0003] However, in the current technology, the existing zinc suberate salt has poor dispersibility and low crystallinity, which results in poor nucleation effect on polylactic acid. Therefore, there is an urgent need to develop a method for preparing zinc suberate nanosheets with good dispersibility and high crystallinity. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, in a first aspect, the present invention provides a method for preparing zinc suberate nanosheets. The zinc suberate nanosheets prepared by this method have good dispersibility and high crystallinity, and can effectively increase the crystallinity of polylactic acid as a nucleating agent.

[0005] The second aspect of the present invention further provides zinc suberate nanosheets.

[0006] The third aspect of the present invention further provides an application of zinc suberate nanosheets.

[0007] According to a first aspect of the present invention, a method for preparing zinc suberate nanosheets is provided, comprising the following steps:

[0008] The preparation method is prepared by mixing sodium suberate, zinc chloride and a solvent, stirring, heating, ultrasonicating and solid-liquid separation.

[0009] According to a preferred embodiment of the present invention, the frequency of the ultrasound is 40 kHz to 45 kHz, for example, including 40 kHz, 42 kHz, 45 kHz, or a sub-range consisting of any two values.

[0010] According to a preferred embodiment of the present invention, the ultrasonic treatment time is 60 minutes to 120 minutes, thereby ensuring that the raw materials fully react.

[0011] According to a preferred embodiment of the present invention, the heating temperature is 30° C. to 80° C., for example, including 30° C., 40° C., 50° C., 60° C., 70° C., 80° C., or a sub-range consisting of any two values.

[0012] According to a preferred embodiment of the present invention, the molar ratio of zinc chloride to sodium suberate is (1.1-1.5): 1. This ensures that the sodium suberate reacts completely.

[0013] According to a preferred embodiment of the present invention, the stirring speed is 500 rpm to 1200 rpm, thereby further improving the dispersion performance.

[0014] According to a preferred embodiment of the present invention, the sodium suberate is prepared by the following method:

[0015] The product is obtained by subjecting suberic acid and sodium hydroxide to acid-base neutralization reaction.

[0016] According to a preferred embodiment of the present invention, during the preparation process, acid (such as hydrochloric acid) needs to be added to inhibit the hydrolysis of zinc chloride.

[0017] According to a preferred embodiment of the present invention, the solvent includes water.

[0018] According to a preferred embodiment of the present invention, the solid-liquid separation method includes differential centrifugation.

[0019] According to a preferred embodiment of the present invention, the product obtained by solid-liquid separation is dried.

[0020] The preparation method according to the embodiment of the present invention has at least the following beneficial effects:

[0021] The present invention finds that by introducing an ultrasonic step during the reaction of sodium suberate and zinc chloride, zinc suberate nanosheets with better dispersion performance and higher crystallinity (fewer surface defect sites, smoother surface, and better crystal quality) can be prepared. The zinc suberate nanosheets are used to modify polylactic acid films, thereby improving the crystallinity of the polylactic acid films.

[0022] According to a second aspect of the present invention, there is provided a zinc suberate nanosheet, which is prepared by the preparation method described in the first aspect of the present invention.

[0023] According to a preferred embodiment of the present invention, the thickness of the zinc suberate nanosheets is 30 nm to 50 nm. Therefore, when used as a polylactic acid nucleating agent, the crystallinity of the polylactic acid film can be improved.

[0024] The third aspect of the present invention provides a use of zinc suberate nanosheets prepared by the preparation method described in the first aspect of the present invention in preparing a polylactic acid film, thereby improving the crystallinity of the polylactic acid film.

[0025] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0027] Figure 1 1 is a SEM image of the product of Example 1 of the present invention and Comparative Example 1;

[0028] Figure 2 is the EDS spectrum of the product prepared in Example 1 of the present invention;

[0029] Figure 3 is the FT-IR graph of the product prepared in Example 1 of the present invention;

[0030] Figure 4 is the XRD pattern of the product prepared in Example 1 of the present invention;

[0031] Figure 5 1 is an XRD pattern of polylactic acid films prepared from the products of Example 1 of the present invention and Comparative Example 1;

[0032] Figure 6 3 is a Raman spectrum of the polylactic acid film prepared from the products of Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0033] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0034] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0035] The sodium suberate used in the Examples and Comparative Examples of the present invention was prepared by the following method:

[0036] First, using a weighing balance, 180 mg of sodium hydroxide was weighed and dissolved in 20 mL of anhydrous ethanol solution, and 348.4 mg of suberic acid was weighed and dissolved in 10 mL of anhydrous ethanol solution. During this period, magnetic stirring was continuously carried out at a stirring speed of 800 rpm for 3 hours, wherein the molar mass ratio of sodium hydroxide to suberic acid was 2.25:1; then, the suberic acid solution was transferred to a round-bottom flask and preheated to 80° C., and the sodium hydroxide solution was transferred to a spherical dropping funnel, and the dropping rate was adjusted to about 0.1 mL / min. During the process of adding the sodium hydroxide solution, the stirring speed in the round-bottom flask was 1200 rpm. After the sodium hydroxide aqueous solution was added dropwise, stirring was continued for 40 minutes. Finally, the obtained suspension was allowed to cool to room temperature (about 30°C) and then centrifuged (5000 rpm / 7 min) for solid-liquid separation. 5 mL of anhydrous ethanol solution was used to wash the precipitate. The washing-centrifugation operation was repeated three times. The obtained product was then dried in an oven at 105°C for 15 hours. The dried powder was sodium suberic acid salt.

[0037] Example 1

[0038] This example provides a zinc suberate nanosheet, the preparation method of which is as follows:

[0039] 218.2 mg of sodium suberate was dissolved in 10 mL of deionized water, 163.6 mg of zinc chloride was dissolved in 10 mL of deionized water, and hydrochloric acid (about 0.1 mL) was added dropwise to inhibit the hydrolysis of zinc chloride. The mixture was magnetically stirred at a stirring speed of 800 rpm for 40 minutes until the sodium suberate and zinc chloride were completely dissolved, wherein the molar mass ratio of zinc chloride to sodium suberate was 1.2:1; then, the sodium suberate aqueous solution was transferred to a centrifuge tube and preheated to 80° C. in an ultrasonic cleaning machine, the zinc chloride solution was transferred to a spherical dropping funnel, and the dripping rate was adjusted to about 0.1 mL / min. During the process of adding the zinc chloride solution to the sodium suberate aqueous solution, the power of the ultrasonic cleaning machine was 70% and the frequency was 40 kHz. After the zinc chloride aqueous solution was added dropwise, the solution was ultrasonicated for 1 hour. Finally, the resulting suspension was allowed to cool to approximately 30°C; solid-liquid separation was performed using a centrifuge (5000 rpm / 7 min), and the precipitate was washed with 5 mL of deionized water. The washing-centrifugation operation was repeated three times, and the resulting product was then dried in an oven at 105°C for 12 hours to obtain zinc suberate nanosheets with an average yield of 84.68%.

[0040] Comparative Example 1

[0041] This example provides a zinc suberate, and its preparation method is as follows:

[0042] 218.2 mg of sodium suberate was weighed and dissolved in 10 mL of deionized water, 163.6 mg of zinc chloride was weighed and dissolved in 10 mL of deionized water, and hydrochloric acid (about 0.1 mL) was added dropwise to inhibit the hydrolysis of zinc chloride. The mixture was magnetically stirred at a stirring speed of 800 rpm for 40 minutes until the sodium suberate and zinc chloride were completely dissolved, wherein the molar mass ratio of zinc chloride to sodium suberate was 1.2:1; then, the sodium suberate aqueous solution was transferred to a round-bottom flask and preheated to 80° C. The zinc chloride solution was transferred to a spherical dropping funnel and the dripping rate was adjusted to about 0.1 mL / min. During the process of adding the zinc chloride solution to the sodium suberate aqueous solution, the stirring speed in the round-bottom flask was 1200 rpm. After the zinc chloride aqueous solution was added dropwise, stirring was continued for 1 hour. Finally, the resulting suspension was allowed to cool to approximately 30°C; solid-liquid separation was performed using a centrifuge (5000 rpm / 7 min), and the precipitate was washed with 5 mL of deionized water. The washing-centrifugation operation was repeated three times, and the resulting product was dried in an oven at 105°C for 15 hours. The dried powder was zinc suberate with an average yield of 64.5%.

[0043] Performance Testing

[0044] The zinc suberate nanosheets prepared in Example 1 of the present invention and the zinc suberate salt prepared in Comparative Example 1 were subjected to SEM testing, and the results are as follows: Figure 1 As shown, Figure 1 a is the SEM image of Example 1, Figure 1 b is the SEM image of comparative example 1, showing that the zinc suberate nanosheets of Example 1 of the present invention have a thickness of 40-50 nm, while the zinc suberate of comparative example 1 has a thickness of about 350 nm. The zinc suberate nanosheets of Example 1 of the present invention are smaller and have good dispersibility.

[0045] Furthermore, the zinc suberate nanosheets of Example 1 of the present invention were subjected to EDS spectrum testing, and the results were as follows: Figure 2 As shown, the contents of C, O, and Zn elements in the synthesized material are very high, which also shows that the material synthesized by the present invention exhibits high purity.

[0046] Furthermore, the sodium suberate prepared by the present invention and the zinc suberate nanosheets prepared in Example 1 were subjected to FT-IR testing, and the results were as follows: Figure 3 As shown in the FTIR spectrum, suberic acid is observed at 1690 cm -1 The C=O stretching vibration peak near 3300-2500 cm -1 The absorption peak caused by OH stretching nearby does not appear in the spectra of sodium and zinc salts of suberic acid, but at 1579-1563 cm -1 and 1405cm -1The antisymmetric stretching vibration and symmetric stretching vibration peaks of (-COO-) were observed nearby, indicating that the designed sodium suberate and zinc suberate were generated in the series of reactions of suberic acid.

[0047] Furthermore, the zinc suberate nanosheets prepared in Example 1 of the present invention and the zinc suberate prepared in Comparative Example 1 were subjected to XRD tests, and the results were as follows: Figure 4 As shown in the figure, it can be found that relatively strong diffraction peaks are observed near 9.5° and 20.5° for the zinc suberate salt synthesized in Example 1 and Comparative Example 1. In addition, the diffraction peaks of the zinc suberate nanosheets prepared in Example 1 of the present invention at 9.5° and 20.5° are sharper and stronger, which is a significant high crystallinity feature of the zinc suberate nanosheets in Example 1 of the present invention, specifically manifested in a significantly reduced surface defect density of the nanosheets and a smoother morphology, which is consistent with the Figure 1 The surface morphology of the nanosheets observed in a is consistent with that in FIG. In contrast, the crystallinity of the product obtained in Comparative Example 1 is relatively low, which is mainly attributed to the presence of obvious defect structures on its surface (such as Figure 1 This structural difference is directly correlated with the difference in crystallinity between the two.

[0048] Furthermore, the zinc suberate nanosheets prepared in Example 1 of the present invention and the zinc suberate salt prepared in Comparative Example 1 were used to prepare a polylactic acid film, respectively, in the following steps:

[0049] 9 mg of zinc suberate (Example 1 and Comparative Example 1) and 291 mg of poly (L-lactic acid) (PLLA, molecular weight 280,000, Jinan Daigang Bioengineering Co., Ltd.) were weighed and ultrasonically physically blended. The mixture was dissolved in dichloromethane solvent and ultrasonicated for 2 hours after continuous magnetic stirring for 4 hours at room temperature. Subsequently, 5 mL of the mixed solution was evenly cast in a flat-bottomed glass culture dish with a diameter of 6 cm, the surface was covered with a glass culture dish to control the volatilization rate, and dried at room temperature in a fume hood for 15 hours to form a homogeneous film with a thickness of 40-43 μm. Then, XRD characterization analysis of the poly (L-lactic acid) film doped with zinc suberate was performed using an X's pert Pro X-ray diffractometer.

[0050] XRD results are as follows Figure 5As shown, the diffraction peak located near 16.8° is the diffraction peak of the polylactic acid (110) / (200) crystal plane. If the ratio of the area of the diffraction peak of the crystal plane to the area under the entire spectrum curve between 10° and 30° is taken as the relative crystallinity of the (110) / (220) crystal plane, the relative crystallinity of the polylactic acid pure film (110) / (220) crystal plane is 26.68%, the relative crystallinity of the polylactic acid / zinc suberate (comparative experiment 3) composite film (110) / (220) crystal plane is 18.13%, the relative crystallinity of the polylactic acid / zinc suberate (comparative example 1) composite film (110) / (220) crystal plane is 18.45%, and the relative crystallinity of the polylactic acid / zinc suberate (implementation example 1) composite film (110) / (220) crystal plane is 40.28%.

[0051] Furthermore, the polylactic acid films prepared in Example 1 and Comparative Example 1 were subjected to Raman spectroscopy tests, and the results are as follows: Figure 6 As shown in the figure, the peak intensity of the Raman scattering peak of the polylactic acid film containing the zinc suberate nanosheets of Example 1 of the present invention is significantly enhanced, which also proves that the zinc suberate nanosheets of Example 1 have a better nucleation effect on the polylactic acid. This shows that the zinc suberate of Example 1 of the present invention is more effective in improving the crystallinity of polylactic acid.

[0052] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the scope of the present invention.

Claims

1. A method for preparing zinc suberate nanosheets, characterized in that: The steps include: The preparation method is prepared by mixing sodium suberate, zinc chloride and a solvent, stirring, heating, ultrasonicating and solid-liquid separation.

2. The preparation method according to claim 1, characterized in that The frequency of the ultrasound is 40kHz to 45kHz.

3. The preparation method according to claim 1 or 2, characterized in that The ultrasonic time is 40 min to 120 min.

4. The preparation method according to claim 1, characterized in that The heating temperature is 30°C to 80°C.

5. The preparation method according to claim 1, characterized in that The molar ratio of the zinc chloride to sodium suberate is (1.1-1.5):

1.

6. The preparation method according to claim 1, characterized in that The stirring speed is 500 rpm to 1200 rpm.

7. The preparation method according to claim 1, characterized in that The sodium suberate is prepared by the following method: The product is obtained by subjecting suberic acid and sodium hydroxide to acid-base neutralization reaction.

8. A zinc suberate nanosheet, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 7.

9. The zinc suberate nanosheet according to claim 8, characterized in that The thickness of the zinc suberate nanosheets is 30 nm to 50 nm.

10. Use of zinc suberate nanosheets prepared according to the preparation method according to any one of claims 1 to 7 in the preparation of polylactic acid films.

Images