Methyl methacrylate polymerization method with programmed pressure relief control

Abstract

The invention relates to the technical field of polymer synthesis, in particular to a polymerization method of methyl methacrylate with programmed pressure relief control. The polymerization method comprises the following steps: pressurizing methyl methacrylate from normal pressure to a first threshold pressure, then releasing the pressure to a second threshold pressure, maintaining the pressure, and then releasing the pressure to normal pressure to prepare the polymethyl methacrylate (PMMA), wherein the first threshold pressure is more than 8 GPa; and the second threshold pressure ranges from 0.2 GPa to 0.5 GPa. The polymerization method disclosed by the invention is simple and convenient to operate, a polymerization product with high conversion rate can be obtained only by controlling the pressure change, a simple and convenient method is provided for controlling high-pressure reaction conditions by programmed pressure relief, and enlightenment is provided for the development of a high-pressure technology in the future.

Description

Technical Field

[0001] The invention relates to the technical field of polymer synthesis, and in particular to a polymerization method of methyl methacrylate controlled by programmed pressure increase and release. Background Art

[0002] There are some problems with the reproducibility of high-pressure chemical reactions carried out by traditional manual pressure loading / unloading. Different researchers sometimes get different experimental results. The reason is usually that the pressure loading mode required for the experiment is different, including the pressure loading and unloading rate, pressure loading and unloading amplitude, and the number of pressure loading and unloading cycles. It is difficult to fully reproduce these parameters with the traditional pressure loading and unloading mode. Therefore, it is necessary to develop a technology that can accurately control the pressure change so that the path of the high-pressure reaction can be fully reproduced.

[0003] Methyl methacrylate (MMA) is a monomer widely used in the field of polymers and is usually a representative of polymer synthesis. It can be polymerized into polymethyl methacrylate (PMMA) through a free radical process. PMMA is also an important polymer used in many important fields, such as aircraft manufacturing, electrical instruments, and medical equipment. Previous studies have confirmed that MMA can be polymerized into PMMA at 80°C in the presence of catalysts such as peroxides. In addition, in the presence of triethylamine, pyrene and anthracene can photoinitiate the polymerization of MMA. However, the polymerization of MMA initiated by pressure alone has not been systematically studied. Summary of the invention

[0004] In order to improve the deficiencies of the prior art, the present invention provides a polymerization method of methyl methacrylate with programmed pressure increase and release control. The polymerization method is a polymerization reaction triggered by pressure, and no solvent or catalyst is required during the reaction process, so it is a green polymerization method. In addition, the polymerization method can accurately control the change of pressure, so that the path of the high-pressure reaction can be completely reproduced, and the conversion rate of the polymerization reaction is high, which can reach more than 65%.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] A polymerization method for methyl methacrylate (MMA), comprising the following steps:

[0007] The polymethyl methacrylate (PMMA) is prepared by pressurizing methyl methacrylate from normal pressure to a first threshold pressure, then releasing the pressure to a second threshold pressure, maintaining the pressure, and then releasing the pressure to normal pressure;

[0008] Among them, the first threshold pressure is above 8 GPa; the second threshold pressure is 0.2 GPa-0.5 GPa.

[0009] According to an embodiment of the present invention, preferably, the first threshold pressure is 8 GPa-15 GPa, for example, 8 GPa, 8.5 GPa, 9 GPa, 9.5 GPa, 10 GPa, 10.5 GPa, 11 GPa, 11.5 GPa, 12 GPa, 12.5 GPa, 13 GPa, 13.5 GPa, 14 GPa, 14.5 GPa or 15 GPa.

[0010] According to an embodiment of the present invention, during the process of pressurizing from normal pressure to the first threshold pressure, the rate of pressurization can be set arbitrarily without special limitation, for example, 0.1 GPa / s-10 GPa / s, such as 0.1 GPa / s, 0.2 GPa / s, 0.4 GPa / s, 1 GPa / s, 2 GPa / s, 5 GPa / s or 10 GPa / s. During the process of pressurizing from normal pressure to the first threshold pressure, the waveform of the pressurized pressure changing with time can be arbitrarily adjusted by the programmed pressure-adding and unloading system, such as a sine waveform, a triangular waveform, a rectangular waveform or other regular or irregular waveforms.

[0011] According to an embodiment of the present invention, during the process of unloading pressure from the first threshold pressure to the second threshold pressure, the rate of unloading pressure can be set arbitrarily without special limitation, for example, 0.1 GPa / s-10 GPa / s, such as 0.1 GPa / s, 0.2 GPa / s, 0.4 GPa / s, 1 GPa / s, 2 GPa / s, 5 GPa / s or 10 GPa / s. During the process of unloading pressure from the first threshold pressure to the second threshold pressure, the waveform of the pressure of unloading pressure changing with time can be arbitrarily adjusted by the programmed pressure-addition and unloading system, such as other regular or irregular waveforms such as sine waveform, triangular waveform, rectangular waveform, etc.

[0012] According to an embodiment of the present invention, after pressurizing from normal pressure to the first threshold pressure, it can be maintained for any time, for example, more than 0 hours, such as 0-3 hours, such as 0s, 1s, 10s, 30s, 1min, 10min, 30min, 1h, 2h or 3h.

[0013] According to an embodiment of the present invention, preferably, the second threshold pressure is 0.2 GPa, 0.3 GPa, 0.4 GPa or 0.5 GPa.

[0014] According to an embodiment of the present invention, the pressure holding time is more than 1 hour, such as more than 3 hours, for example, 3 hours to 48 hours, for example, 3 hours, 4 hours, 6 hours, 8 hours, 12 hours, 18 hours, 24 hours, 36 hours or 48 hours.

[0015] According to an embodiment of the present invention, during the process of unloading to normal pressure after pressure maintenance, the rate of pressure relief can be set arbitrarily without special limitation, for example, 0.1GPa / s-10GPa / s, such as 0.1GPa / s, 0.2GPa / s, 0.4GPa / s, 1GPa / s, 2GPa / s, 5GPa / s or 10GPa / s. During the process of unloading to normal pressure after pressure maintenance, the waveform of the pressure relief pressure changing with time can be arbitrarily adjusted by the programmed pressure addition and unloading system, such as other regular or irregular waveforms such as sine waveform, triangular waveform, rectangular waveform, etc.

[0016] According to an embodiment of the present invention, the polymerization method further comprises the following steps:

[0017] After methyl methacrylate is pressurized from normal pressure to a first threshold pressure, a repeated pressurization and depressurization step is performed, and then the pressure is depressurized to a second threshold pressure.

[0018] According to an embodiment of the present invention, the introduction of the repeated pressure increase and reduction step can improve the conversion rate of the polymerization reaction.

[0019] According to an embodiment of the present invention, the number of repeated pressure increase and reduction is more than 1 time, for example, 1-100 times, such as 1 time, 10 times, 20 times, 30 times, 40 times, 50 times, 60 times, 70 times, 80 times, 90 times or 100 times.

[0020] According to an embodiment of the present invention, the pressure range of the repeated pressurization and unloading is 0.5GPa-9GPa, for example, 0.5GPa, 1GPa, 1.5GPa, 2GPa, 2.5GPa, 3GPa, 3.5GPa, 4GPa, 4.5GPa, 5GPa, 5.5GPa, 6GPa, 6.5GPa, 7GPa, 7.5GPa, 8GPa, 8.5GPa or 9GPa. Exemplarily, the maximum pressure range of the repeated pressurization and unloading is 8GPa-10GPa, and the minimum pressure range is 0.5GPa-7GPa, such as pressurizing from 0.5GPa to 8GPa and then unloading to 1GPa, such as pressurizing from 1GPa to 10GPa and then unloading to 2GPa.

[0021] According to an embodiment of the present invention, during the repeated pressure-adding and unloading process, the pressure-adding and unloading rate can be set arbitrarily without any particular limitation. For example, it is 0.1-10 GPa / s, such as 0.1 GPa / s, 0.2 GPa / s, 0.4 GPa / s, 1 GPa / s, 2 GPa / s, 5 GPa / s or 10 GPa / s. During the repeated pressure-adding and unloading process, the waveform of the pressure of the repeated pressure-adding and unloading over time can be arbitrarily adjusted by the programmed pressure-adding and unloading system, such as a sine waveform, a triangular waveform, a rectangular waveform or other regular or irregular waveforms.

[0022] According to an embodiment of the present invention, the holding time of the repeated pressure-adding and pressure-releasing process can be set arbitrarily without any particular limitation, for example, more than 0 hours, such as 0-3 hours, such as 0s, 1s, 10s, 30s, 1min, 10min, 30min, 1h, 2h or 3h.

[0023] According to an embodiment of the present invention, the polymerization method comprises the following steps:

[0024] The polymethyl methacrylate is prepared by pressurizing methyl methacrylate to above 8 GPa, then reducing the pressure to 0.2 GPa-0.5 GPa, maintaining the pressure for more than 3 hours, and then reducing the pressure to normal pressure.

[0025] According to an embodiment of the present invention, the polymerization method comprises the following steps:

[0026] After methyl methacrylate is pressurized to above 8 GPa, it is repeatedly pressurized and released within a pressure range of 0.5 GPa-9 GPa for 1-100 times, then the pressure is released to 0.2 GPa-0.5 GPa, the pressure is maintained for more than 1 hour, and then the pressure is released to normal pressure to prepare the polymethyl methacrylate.

[0027] According to an embodiment of the present invention, the conversion rate of MMA can reach up to 65%.

[0028] According to an embodiment of the present invention, the polymerization method is carried out at room temperature.

[0029] According to an embodiment of the present invention, the polymerization method is carried out in a pressurized device, which includes but is not limited to a piston cylinder press.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention provides a method for synthesizing high-purity PMMA. The high-pressure initiation and low-pressure polymerization process provides a new reaction pathway for high-pressure chemical reactions. The polymerization reaction can be promoted by repeatedly adding and removing pressure near 8 GPa, and the reaction conversion rate can be further improved. The polymerization method of the present invention is easy to operate, and a polymerization product with a high conversion rate can be obtained only by controlling the pressure change. The result also provides a simple method for controlling high-pressure reaction conditions by programmed adding and removing pressure, and provides inspiration for the future development of high-pressure technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a comparison chart of the conversion rate of synthesizing PMMA using the method of the present invention.

[0033] Figure 2 This is a morphology image of a sample taken by a high-speed camera during the process of synthesizing PMMA using the method of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0035] If no specific techniques or conditions are specified in the examples, all are carried out according to conventional methods or the techniques or conditions described in the literature in the field, or according to the product instructions. If no manufacturer is specified for the reagents and instruments used, all are conventional products that can be purchased through regular channels.

[0036] In the following examples, a diamond anvil cell (DAC) device was used to conduct the experiment. A pair of diamonds with a diameter of 500 μm were used to pre-press a 70 μm thick pit in the center of a rhenium sheet, and a circular hole with a diameter of 250 μm was punched in the center of the pit as a sample cavity. Liquid MMA with a purity greater than 99.9% was placed in the sample cavity together with ruby. The DAC was pressurized using a programmed pressurization and depressurization device, a piston cylinder press.

[0037] Example 1

[0038] Apply pressure to 9 GPa at a rate of 0.4 GPa / s and then immediately release the pressure to 7 GPa at a rate of 0.4 GPa / s. Repeat the pressure increase and reduction (apply pressure to 9 GPa at a rate of 0.4 GPa / s and then immediately release the pressure to 7 GPa at a rate of 0.4 GPa / s) 10 times, and then continue to release the pressure to 0.5 GPa at a rate of 0.4 GPa / s to make the sample liquid. Maintain this pressure for 3 hours and release the pressure to normal pressure to obtain the final PMMA solid.

[0039] Example 2

[0040] Apply pressure to 9 GPa at a rate of 0.4 GPa / s, then immediately release the pressure to 7 GPa at a rate of 0.4 GPa / s. Continue to release the pressure to 0.5 GPa at a rate of 0.4 GPa / s to make the sample liquid. Maintain this pressure for 3 hours, and release the pressure to normal pressure to obtain the final PMMA solid.

[0041] Example 3

[0042] Apply pressure to 9 GPa at a rate of 0.4 GPa / s and then immediately release the pressure to 7 GPa at a rate of 0.4 GPa / s. Repeat the pressure increase and reduction (apply pressure to 9 GPa at a rate of 0.4 GPa / s and then immediately release the pressure to 7 GPa at a rate of 0.4 GPa / s) for 100 times, and then continue to release the pressure to 0.5 GPa at a rate of 0.4 GPa / s to make the sample liquid. Maintain this pressure for 3 hours and release the pressure to normal pressure to obtain the final PMMA solid.

[0043] Example 4

[0044] Apply pressure to 9 GPa at a rate of 0.4 GPa / s and then immediately release the pressure to 7 GPa at a rate of 0.4 GPa / s. Repeat the pressure increase and reduction (apply pressure to 9 GPa at a rate of 0.4 GPa / s and then immediately release the pressure to 0.5 GPa at a rate of 0.4 GPa / s) 10 times, and then continue to release the pressure to 0.5 GPa at a rate of 0.4 GPa / s to make the sample liquid. Maintain this pressure for 3 hours and release the pressure to normal pressure to obtain the final PMMA solid.

[0045] Example 5

[0046] Apply pressure to 9 GPa at a rate of 2 GPa / s and then immediately release the pressure to 7 GPa at a rate of 2 GPa / s. Repeat the pressure increase and reduction (apply pressure to 9 GPa at a rate of 2 GPa / s and then immediately release the pressure to 7 GPa at a rate of 2 GPa / s) for 100 times, and then continue to release the pressure to 0.5 GPa at a rate of 2 GPa / s to make the sample liquid. Maintain this pressure for 3 hours and release the pressure to normal pressure to obtain the final PMMA solid.

[0047] Example 6

[0048] Apply pressure to 9 GPa at a rate of 10 GPa / s and then immediately release the pressure to 7 GPa at a rate of 10 GPa / s. Repeat the pressure increase and reduction (apply pressure to 9 GPa at a rate of 10 GPa / s and then immediately release the pressure to 7 GPa at a rate of 10 GPa / s) for 100 times, and then continue to release the pressure to 0.5 GPa at a rate of 10 GPa / s to make the sample liquid. Maintain this pressure for 3 hours and release the pressure to normal pressure to obtain the final PMMA solid.

[0049] Example 7

[0050] After applying pressure to 10 GPa at a rate of 0.4 GPa / s, the pressure was immediately released to 7 GPa at a rate of 0.4 GPa / s. The pressure was further released to 0.5 GPa at a rate of 0.4 GPa / s to make the sample liquid. This pressure was maintained for 3 hours, and the pressure was released to normal pressure to obtain the final PMMA solid.

[0051] Example 8

[0052] The pressure was applied to 7 GPa at a rate of 0.4 GPa / s and then immediately released to 0.5 GPa at a rate of 0.4 GPa / s to make the sample liquid. The pressure was maintained for 3 h and then released to normal pressure to obtain the final PMMA solid.

[0053] Example 9

[0054] The pressure was applied to 9 GPa at a rate of 0.4 GPa / s, and then immediately released to 7 GPa at a rate of 0.4 GPa / s. The pressure was further released to 0.6 GPa at a rate of 0.4 GPa / s to maintain the sample in a solid state. This pressure was maintained for 3 hours, and the pressure was released to normal pressure to obtain the final PMMA solid.

[0055] Example 10

[0056] The pressure was applied at a rate of 0.4 GPa / s to 9 GPa and then maintained for 3 hours. The pressure was then released at a rate of 0.4 GPa / s to 7 GPa. The pressure was further released at a rate of 0.4 GPa / s to 0.5 GPa to make the sample liquid. The pressure was maintained for 3 hours and then released to normal pressure to obtain the final PMMA solid.

[0057] Embodiment 11

[0058] Apply pressure to 9 GPa at a rate of 0.4 GPa / s, then immediately release the pressure to 7 GPa at a rate of 0.4 GPa / s. Continue to release the pressure to 0.5 GPa at a rate of 0.4 GPa / s to make the sample liquid. Maintain this pressure for 1 hour, and release the pressure to normal pressure to obtain the final PMMA solid.

[0059] Example 12

[0060] The pressure was applied to 9 GPa at a rate of 0.4 GPa / s, and then immediately released to 7 GPa at a rate of 0.4 GPa / s. The pressure was further released to 0.5 GPa at a rate of 0.4 GPa / s to make the sample liquid. This pressure was maintained for 48 hours, and the pressure was released to normal pressure to obtain the final PMMA solid.

[0061] Test Example 1

[0062] Characterization was performed using Raman spectroscopy with a resolution of <1 cm -1 , Raman shift range is 1400-1800cm -1 The excitation light source is 532nm laser, the spectrum acquisition rate is 1 frame per second, and 20 frames are collected under the same conditions and superimposed to obtain the final Raman spectrum.

[0063] A high-speed camera and a microscope were used to observe the changes in sample morphology during the reaction.

[0064] The conversion rate of the reaction was calculated based on the change in the peak intensity ratio of the C=C peak to the C=O peak in the Raman spectrum.

[0065] Figure 1 This is a comparison chart of the conversion rates of the polymerization reactions of Examples 1-12 of the present application. Figure 1 It can be seen that when the pressure increase and decompression amplitude is constant, too few or too many pressure increase and decompression cycles will reduce the conversion rate. In order to obtain a higher conversion rate, the number of pressure increase and decompression can be controlled to 10 times, or the pressure increase and decompression cycle amplitude can be increased, or the pressure holding time of the sample in the liquid state can be extended. The pressure increase and decompression rate and the pressure holding time of the sample at the first threshold pressure have no obvious effect on the conversion rate.

[0066] Figure 2 The three columns from left to right correspond to the MMA sample just loaded into the DAC, the sample after decompression to the second threshold pressure and pressure maintenance, and the sample taken out after complete decompression. Figure 2 It can be seen that when the pressure-adding and unloading amplitude is 7-9 GPa, using too few (1 time) or too many (100 times) times will not ultimately produce a complete product. However, using a moderate number (10 times) can produce a complete product. In addition, when the pressure-adding and unloading amplitude is increased to 0.5-9 GPa, the product is more complete and harder. This shows that the first threshold pressure, the second threshold pressure, and the holding time of the sample at the second threshold pressure all have an impact on the morphology of the product.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0068] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polymerization method for methyl methacrylate (MMA), comprising the following steps: The polymethyl methacrylate (PMMA) is prepared by pressurizing methyl methacrylate from normal pressure to a first threshold pressure, then releasing the pressure to a second threshold pressure, maintaining the pressure, and then releasing the pressure to normal pressure; the first threshold pressure is above 8 GPa; the second threshold pressure is 0.2 GPa-0.5 GPa.

2. The polymerization method according to claim 1, wherein The first threshold pressure is 8 GPa-15 GPa.

3. The polymerization method according to claim 1 or 2, wherein In the process of pressurizing from normal pressure to the first threshold pressure, the pressurizing rate is 0.1 GPa / s-10 GPa / s; in the process of pressurizing from normal pressure to the first threshold pressure, the waveform of the pressurized pressure changing with time is a sine waveform, a triangular waveform, a rectangular waveform or an irregular waveform; And / or, during the process of unloading pressure from the first threshold pressure to the second threshold pressure, the rate of unloading pressure is 0.1 GPa / s-10 GPa / s; during the process of unloading pressure from the first threshold pressure to the second threshold pressure, the waveform of the pressure unloading pressure changing with time is a sine waveform, a triangular waveform, a rectangular waveform or an irregular waveform; And / or, during the process of unloading the pressure to normal pressure after pressure maintenance, the rate of pressure unloading is 0.1GPa / s-10GPa / s; during the process of unloading the pressure to normal pressure after pressure maintenance, the waveform of the pressure unloading changing with time is a sine waveform, a triangular waveform, a rectangular waveform or an irregular waveform.

4. The polymerization method according to any one of claims 1 to 3, wherein After pressurizing from normal pressure to the first threshold pressure, the pressure is maintained for more than 0 hours, such as 0-3 hours.

5. The polymerization method according to any one of claims 1 to 4, wherein The pressure holding time is more than 1 hour, such as more than 3 hours, for example, 3 hours to 48 hours.

6. The polymerization method according to any one of claims 1 to 5, wherein The polymerization method further comprises the following steps: After methyl methacrylate is pressurized from normal pressure to a first threshold pressure, a repeated pressurization and depressurization step is performed, and then the pressure is depressurized to a second threshold pressure.

7. The polymerization method according to claim 6, wherein The number of repeated pressure addition and release is more than 1 time, for example, 1-100 times. Preferably, the pressure range of the repeated pressurization and unloading is 0.5 GPa-9 GPa. Preferably, the maximum pressure range of the repeated pressurization and unloading is 8 GPa-10 GPa, and the minimum pressure range is 0.5 GPa-7 GPa.

8. The polymerization method according to claim 6 or 7, wherein During the repeated pressure increase and unloading process, the pressure increase and unloading rate is 0.1-10GPa / s; during the repeated pressure increase and unloading process, the waveform of the pressure changing with time during the repeated pressure increase and unloading is a sine waveform, a triangular waveform, a rectangular waveform or an irregular waveform. Preferably, the pressure holding time of the repeated pressure-adding and pressure-releasing process is more than 0 hours, such as 0-3 hours.

9. The polymerization method according to any one of claims 1 to 7, wherein: The polymerization method comprises the following steps: The polymethyl methacrylate is prepared by pressurizing methyl methacrylate to above 8 GPa, then reducing the pressure to 0.2 GPa-0.5 GPa, maintaining the pressure for more than 3 hours, and then reducing the pressure to normal pressure.

10. The polymerization method according to any one of claims 1 to 9, wherein The polymerization method comprises the following steps: After methyl methacrylate is pressurized to above 8 GPa, it is repeatedly pressurized and released within a pressure range of 0.5 GPa-9 GPa for 1-100 times, then the pressure is released to 0.2 GPa-0.5 GPa, the pressure is maintained for more than 1 hour, and then the pressure is released to normal pressure to prepare the polymethyl methacrylate.

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