A preparation method of PBAT-FITC material

Abstract

The present invention discloses a method for preparing a PBAT-FITC material, comprising the following steps: (1) taking unmodified ordinary PBAT pellets, mixing them in a high mixer for at least 5 minutes, and evenly spraying a sodium hydroxide solution during the mixing process to evenly mix the sodium hydroxide on the surface of the PBAT particles; (2) melt-extruding and granulating the material obtained in step (1) through a parallel twin-screw extruder, and drying to obtain short-chain PBAT particles; (3) evenly mixing the short-chain PBAT particles with FITC in the dark, placing them in a torque rheometer for reaction, and then taking them out to obtain a PBAT-FITC graft; (4) washing the PBAT-FITC graft until the fluorescence in the washing solution disappears, and drying the washed sample to obtain the PBAT-FITC material. The present invention can simply and quickly prepare a PBAT-FITC material with a high grafting rate and a high fluorescence intensity.

Description

Technical Field

[0001] The invention relates to a method for preparing a PBAT-FITC material. Background Art

[0002] Plastic is a versatile, durable and inexpensive material that is widely used in packaging, construction, textiles and electronics. As plastic products reach the end of their service life or become damaged, a large amount of plastic waste is generated every year. In production and life, due to improper management, these plastic wastes that are not effectively disposed of or improperly disposed of may enter ecosystems such as the ocean in the form of plastic fragments or particles, and spread and migrate in them, eventually leading to global plastic pollution.

[0003] What is more worthy of attention is that when plastic is released into the environment, it may undergo processes such as ultraviolet radiation, mechanical wear, and biodegradation, thereby forming smaller fragments and causing more serious plastic pollution. These plastic fragments may cause certain harm to aquatic organisms and the environment, such as causing feeding disorders, intestinal obstruction, and even death in some aquatic animals. In recent years, the hazards of MPs have been particularly concerning and have been listed as one of the major global environmental issues. In the face of the increasingly prominent MPs pollution problem, many studies have shown that MPs have toxic effects on organisms. Therefore, it is necessary to conduct further research and discussion on the environmental behavior, toxic effects, and mechanisms of action of MPs.

[0004] Fluorescence quantitative method is a common laboratory method for studying the environmental and biological hazards of microplastics. By marking microplastics with fluorescence, the aggregation sites of nanoplastics can be observed, which is conducive to observing the effects of microplastics on target organs in organisms. The common method of fluorescently labeling microplastics is generally solution grafting. Grafting in the laboratory takes 1-3 days, which is time-consuming and inefficient. In addition, the subsequent removal of excess fluorescein requires dialysis for 3-5 days, which wastes a lot of water resources and reduces the synthesis efficiency. The present invention accelerates the reaction through the method of melt grafting to obtain more fluorescently labeled plastics. Summary of the invention

[0005] The purpose of the present invention is to provide a method for simply and quickly preparing a PBAT-FITC material with a high grafting rate and high fluorescence intensity.

[0006] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0007] A method for preparing a PBAT-FITC material comprises the following steps:

[0008] (1) Take unmodified ordinary PBAT pellets and mix them in a high-speed mixer for at least 5 minutes. During the mixing process, evenly spray 0.5 mol / L-1.5 mol / L sodium hydroxide solution to make the sodium hydroxide evenly mixed on the surface of the PBAT particles; the feed ratio of the ordinary PBAT pellets to the sodium hydroxide solution is 1 kg: 100-200 mL;

[0009] (2) melt-extrude the material obtained in step (1) through a parallel twin-screw extruder, granulate it, and dry it to obtain short-chain PBAT particles;

[0010] (3) The short-chain PBAT particles obtained in step (2) are mixed evenly with FITC in the dark, placed in a torque rheometer and mixed at 130° C.-140° C. for 5-25 minutes, and then taken out to obtain a PBAT-FITC product; the FITC refers to fluorescein isothiocyanate, and the mass ratio of the short-chain PBAT particles to FITC is 45-55:1;

[0011] (4) The PBAT-FITC product is dissolved in chloroform, and then washed with ethanol pre-cooled to below 5°C until the fluorescence in the washing solution disappears. During washing, the volume ratio of ethanol to chloroform is ≥10 to ensure that PBAT can be completely precipitated and the excess FITC is washed away. Finally, the washed sample is dried to obtain the PBAT-FITC material.

[0012] Preferably, in step (1), the speed of the high-speed mixer is 700-900 r / min, the mixing time of PBAT is 5-25 min, more preferably 15 min, and the speed is 800 r / min.

[0013] Preferably, in step (1), the concentration of the sodium hydroxide solution is 0.5 mol / L, and the feed ratio of the ordinary PBAT pellets to the sodium hydroxide solution is 1 kg: 150 mL.

[0014] Preferably, the extrusion conditions of the twin-screw extruder in step (2) are: extrusion temperature of 140-170° C., and screw speed of 300-400 r / min.

[0015] Preferably, the reaction conditions in the torque rheometer in step (3) are: temperature of 140° C. and time of 15 min.

[0016] Preferably, in step (4), the drying is performed by placing the product in a forced air drying oven for 1-2 hours.

[0017] Preferably, in step (4), the ethanol temperature is cooled to 0-5°C in advance.

[0018] The common PBAT described in the present invention is the unmodified PBAT granules purchased on the market, and the FITC is fluorescein isothiocyanate, and in the specific implementation, fluorescein isothiocyanate isomer I (FITC-I) is used. The reaction between the short-chain PBAT terminal hydroxyl group and FITC refers to the following reaction:

[0019]

[0020] The PBAT-FITC material prepared by the present invention uses FITC that can emit fluorescence to label PBAT plastic, has high fluorescence intensity, and can be used as a PBAT plastic tracer material.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) Compared with the traditional emulsion method for grafting FITC, the present invention can quickly produce a large amount of PBAT-FITC products, reduce reaction time and reduce costs.

[0023] (2) The short-chain PBAT prepared by the present invention has more terminal hydroxyl groups than ordinary PBAT, which greatly improves the grafting rate of FITC.

[0024] (3) The present invention uses an organic solvent dissolution and then ethanol precipitation method to clean the ungrafted FITC in the product. The ethanol is cooled in advance, so that when cleaning PBAT, the agglomeration of PBAT can be reduced, so that the PBAT is completely precipitated and the excess FITC is cleaned faster.

[0025] (4) The PBAT-FITC material prepared by the present invention has a high fluorescence intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the infrared spectrum of PBAT grafted with FITC in Example 5

[0027] Figure 2 This is a fluorescence microscope picture of PBAT after FITC was grafted onto it in Example 5. Specific implementation plan

[0028] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the present invention, not all of it. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1:

[0030] 1 kg of ordinary PBAT pellets (Hengli Group, KHB21AP11, MFR 3.8 g / 10 min (190 ° C, 2.16 kg) were mixed in a high-speed mixer (SHR-100A, Zhangjiagang Xinyuan Machinery) for 5 min (800 r / min), and 100 ml of 0.5 mol / L sodium hydroxide solution was evenly sprayed during the mixing process to make the sodium hydroxide evenly mixed on the surface of the PBAT particles.

[0031] The obtained material was extruded (165°C, 300r / min) and granulated by a parallel twin-screw extruder (SHJ-35B, Nanjing Juli Chemical Machinery), and short-chain PBAT particles were obtained after drying. The MFR of the short-chain PBAT particles was 200g / 10min (190°C, 2.16kg) using a melt flow rate (MFR) instrument. In contrast, ordinary PBAT pellets were not treated with sodium hydroxide solution, but were directly melt-extruded and granulated according to the above conditions, and ordinary PBAT particles were obtained after drying. The MFR of the short-chain PBAT particles was 137g / 10min (190°C, 2.16kg) using a melt flow rate (MFR) instrument.

[0032] Take 50g of the dried short-chain PBAT particles and 1g of FITC-I, mix them in the dark, add them into the torque rheometer (HAKE torque rheometer polylab A), mix them at 140°C for 5min, take them out and store them in the dark.

[0033] Take 1g of sample and dissolve it in 5ml of chloroform, pour it into 50ml of ethanol refrigerated at 4℃ to clean the excess FITC-I in the sample, take a drop of the washed solution and place it under a fluorescence microscope (Observer A One, Carl Zeiss, Germany) to observe whether there is fluorescence, repeat the washing several times until the fluorescence in the washing solution disappears, place the obtained sample in an oven at 40℃ to dry, and observe the grafting of FITC under a fluorescence microscope after sample preparation. Take 1mg of the washed sample and dissolve it in 1ml of chloroform, and use an enzyme marker (Synergy H1, Berton Instruments, USA) to detect the fluorescence intensity. The results are shown in Table 1.

[0034] Embodiment 2:

[0035] The same as Example 1, but the treatment conditions for PBAT were changed to mixing in a high-speed mixer for 15 minutes, and the other steps and conditions remained unchanged, and the fluorescence intensity of the obtained PBAT-FITC product was measured, and the results are shown in Table 1. The results are shown in the following table, indicating that when the other conditions remain unchanged, the PBAT mixed with the sodium hydroxide solution is more uniform, the alkaline degradation time is longer, the molecular chain segment is shorter, and the fluorescence intensity of the obtained PBAT-FITC product is higher.

[0036] Table 1

[0037] PBAT-FITC product Fluorescence intensity Example 1 3396 Example 2 4990

[0038] Embodiment 3:

[0039] The same as Example 2, but the treatment condition of PBAT was changed to mixing in a high-speed mixer for 25 minutes, and the other steps and conditions remained unchanged, and the fluorescence intensity of the obtained PBAT-FITC product was measured, and the results are shown in Table 2. Too long mixing time will cause the precipitation of sodium hydroxide, affecting the subsequent alkaline degradation process and affecting the grafting effect of FITC.

[0040] Table 2

[0041] PBAT-FITC product Fluorescence intensity Example 2 4990 Example 3 3870

[0042] Embodiment 4:

[0043] The same as Example 2, but the treatment condition for PBAT was changed to uniformly spraying 150 ml of 0.5 mol / L sodium hydroxide solution during the mixing process, and the other steps and conditions remained unchanged. The fluorescence intensity of the obtained PBAT-FITC product was measured to be enhanced. The results are shown in Table 3, indicating that increasing the volume of the sodium hydroxide solution can appropriately increase the degradation effect of PBAT and increase the content of short-chain PBAT.

[0044] Table 3

[0045] PBAT-FITC product Fluorescence intensity Example 2 4990 Example 4 5226

[0046] Comparative Example 1: Ordinary PBAT was used to prepare a PBAT-FITC graft with fluorescence intensity.

[0047] Same as Example 4, the short-chain PBAT particles were replaced with the ordinary PBAT particles prepared in Example 1, and the other steps and conditions remained unchanged. Finally, the fluorescence intensity of the two prepared PBAT-FITC samples was detected, and the results are shown in Table 3 below. It shows that after the short-chain PBAT was grafted with FITC, the fluorescence intensity of the prepared sample was higher than that of the sample after the ordinary PBAT was grafted. The short-chain PBAT does have more hydroxyl groups and a higher grafting rate, which significantly improves the fluorescence intensity of the PBAT-FITC sample.

[0048] Table 3

[0049] PBAT-FITC product Fluorescence intensity Comparative Example 1 3250 Example 4 5226

[0050] Embodiment 5:

[0051] The same as Example 4, but the reaction conditions of PBAT and FITC-I in the torque rheometer were changed to 140°C for 15 min, and the other steps remained unchanged. Finally, the fluorescence intensity of the two prepared PBAT-FITC samples was detected. The results are shown in Table 4, indicating that slightly extending the reaction time in the torque rheometer can increase the fluorescence intensity of the grafted product.

[0052] Table 4

[0053] PBAT-FITC product Fluorescence intensity Example 4 5226 Example 5 5770

[0054] Comparative Example 2:

[0055] Same as Example 5, the short-chain PBAT particles were replaced with the ordinary PBAT particles prepared in Example 1, and the other conditions remained unchanged. The test results are as follows, indicating that the fluorescence intensity of the untreated PBAT is lower than that of the short-chain PBAT.

[0056] Table 3

[0057] PBAT-FITC product Fluorescence intensity Comparative Example 2 3125 Example 5 5770

[0058] Comparative Example 3:

[0059] Same as Example 4, the ethanol used to precipitate PBAT was replaced with ethanol at room temperature that had not been refrigerated, and the other conditions remained unchanged. It was found that the precipitation effect of ethanol at room temperature was poor, it was difficult to obtain the precipitation product, and the fluorescence intensity could not be detected, indicating that ethanol at room temperature could not be used to precipitate PBAT.

Claims

1. A method for preparing a PBAT-FITC material, characterized in that: The preparation method comprises the following steps: (1) Take unmodified ordinary PBAT pellets and mix them in a high-speed mixer for at least 5 minutes. During the mixing process, evenly spray 0.5 mol / L-1.5 mol / L sodium hydroxide solution to make the sodium hydroxide evenly mixed on the surface of the PBAT particles; the feed ratio of the ordinary PBAT pellets to the sodium hydroxide solution is 1 kg: 100-200 mL; (2) melt-extrude the material obtained in step (1) through a parallel twin-screw extruder, granulate it, and dry it to obtain short-chain PBAT particles; (3) The short-chain PBAT particles obtained in step (2) are mixed evenly with FITC in the dark, placed in a torque rheometer and mixed at 130° C.-140° C. for 5-25 minutes, and then taken out to obtain a PBAT-FITC product; the FITC refers to fluorescein isothiocyanate, and the mass ratio of the short-chain PBAT particles to FITC is 45-55:1; (4) The PBAT-FITC product is dissolved in chloroform, and then washed with ethanol pre-cooled to below 5°C until the fluorescence in the washing solution disappears. During washing, the volume ratio of ethanol to chloroform is ≥10 to ensure that PBAT can be completely precipitated and the excess FITC is washed away. Finally, the washed sample is dried to obtain the PBAT-FITC material.

2. The preparation method according to claim 1, characterized in that: In step (1), the speed of the high speed mixer is 700-900 r / min, and the mixing time of PBAT is 5-25 min.

3. The preparation method according to claim 1, characterized in that: In step (1), the concentration of the sodium hydroxide solution is 0.5 mol / L, and the feed ratio of the ordinary PBAT pellets to the sodium hydroxide solution is 1 kg: 150 mL.

4. The preparation method according to claim 1, characterized in that: The extrusion conditions of the twin-screw extruder in step (2) are: extrusion temperature of 140-170° C., and screw speed of 300-400 r / min.

5. The preparation method according to claim 1, characterized in that: The reaction conditions in the torque rheometer in step (3) are: temperature of 140° C. and time of 15 min.

6. The preparation method according to claim 1, characterized in that: In step (4), the drying is performed by placing the product in a forced air drying oven for 1-2 hours.

7. The preparation method according to claim 1, characterized in that: In step (4), the ethanol temperature is cooled to 0-5°C in advance.

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