Preparation of biodegradable and recyclable thermosetting materials based on 7-oxo-2,3-diazanorbornene monomer

Abstract

The present invention provides a cross-linked polymer P-MX-DCPD based on the monomers 7-oxygen-2,3-diazanorbornene (MX) and DCPD. The resulting cross-linked polymer uses industrially scalable raw materials, 7-oxygen-2,3-diazanorbornene and DCPD, so the cross-linked polymer P-MX-DCPD can also be industrially produced at significantly lower production costs than existing degradable and recyclable cross-linked polymers. More importantly, the cross-linked polymer of the present application is degradable under acidic conditions, and the degradation product can be reused, significantly improving the degradation and recycling difficulties of existing cross-linked polymers.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of degradable polymers, and in particular relates to the synthesis of a degradable and recyclable thermosetting material based on 7-oxo-2,3-diazanorbornene. Background Art

[0002] In the more than 100 years since Hermann Staudinger proposed the macromolecular hypothesis, our society has benefited from the ubiquity of synthetic polymers with outstanding thermal, optical, mechanical, and chemical properties. Thermosets, polymers that retain a permanent shape upon curing, play a key role in the modern plastics and rubber industries, accounting for approximately 20% of today's polymer manufacturing and producing approximately 65 million tons annually worldwide. However, with the increasing production of thermosets and their inherent insolubility and infusibility, the disposal of end-of-life thermoset waste has become a serious problem. Numerous strategies have been proposed to address this issue, including conventional recycling, biodegradation, polymer synthesis from biorenewable resources, and various upcycling technologies. Among these, the development of degradable and recyclable thermosets has garnered significant attention, as synthetic chemistry allows for structurally modifying the crosslinking properties of thermosets.

[0003] Ring-opening metathesis polymerization (ROMP) has become one of the most versatile polymerization methods due to its mild reaction conditions and broad functional group compatibility. Using dicyclopentadiene (DCPD) monomer, ROMP polymerization can directly yield the thermosetting cross-linked polymer material PDCPD, which exhibits exceptional mechanical strength and is increasingly being used as a specialty material in areas such as bulletproofing, wind turbine blades, and automobile bumpers. However, like other thermosetting materials, PDCPD is a cross-linked structure composed of chemically stable C—C bonds, which presents significant challenges in post-service recycling and reuse. By introducing degradable functional groups into the monomer and copolymerizing the degradable monomer with DCPD, degradable thermosetting PDCPD materials can be obtained, providing a new approach for the preparation of degradable and recyclable thermosetting materials. However, one of the current limitations of this strategy is the need for specially designed degradable monomers. Furthermore, known degradable monomers either require multi-step synthesis, resulting in an extremely complex preparation process, or suffer from insufficient monomer ring tension, making it difficult to achieve a controlled distribution of degradable groups during DCPD copolymerization. Summary of the Invention

[0004] In order to prepare a degradable and recyclable thermosetting material, the present invention provides a cross-linked polymer based on 7-oxo-2,3-diazanorbornene monomer. Under the action of a ruthenium complex catalyst, the monomer 7-oxo-2,3-diazanorbornene and dicyclopentadiene DCPD are copolymerized to obtain a degradable and recyclable thermosetting material.

[0005] The present invention first provides the following cross-linked polymer P-MX-DCPD based on 7-oxo-2,3-diazanorbornene monomer MX and DCPD:

[0006]

[0007] Among them, R 1 , R 2 The same or different, independently selected from C 1-12 Alkyl, C 1-12 Alkoxy chain formed by replacing 1-6 carbon atoms on the alkyl group with O, -(CH2) p C 6-20 Aryl, p is an integer greater than or equal to 0.

[0008] According to an embodiment of the present invention, the cross-linked polymer P-MX-DCPD structure is as follows:

[0009]

[0010] R 1 , R 2 Having the above definition; (x+y), z are the same or different and are independently an integer from 2 to 200,000.

[0011] According to an embodiment of the present invention, R 1 , R 2 The same or different, independently selected from C 1-6 Alkyl, C 1-6 Alkoxy chain formed by replacing 1-3 carbon atoms on the alkyl group with O, -(CH2) p C 6-12 Aryl, p is an integer of 1-6;

[0012] (x+y), z are the same or different and are independently an integer from 10 to 20,000, for example, an integer from 20 to 2,000.

[0013] According to an embodiment of the present invention, R 1 , R 2 is the same and is selected from methyl, ethyl, propyl, isopropyl, benzyl, butyl, isobutyl or tert-butyl.

[0014] In one embodiment, the cross-linked polymer P-MX-DCPD has the following structure:

[0015]

[0016] wherein (x+y) and z are the same or different and are independently 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 1000 or 2000.

[0017] According to an embodiment of the present invention, the cross-linked polymer P-MX-DCPD is a thermosetting material.

[0018] The present invention also provides a method for preparing the cross-linked polymer P-MX-DCPD, comprising the following steps:

[0019] 7-Oxo-2,3-diazanorbornene monomer MX and DCPD undergo cross-linking polymerization reaction in the presence of ruthenium complex catalyst.

[0020] According to an embodiment of the present invention, the cross-linked polymer reaction is:

[0021]

[0022] According to an embodiment of the present invention, the ruthenium complex catalyst is a common olefin metathesis catalyst containing a ruthenium-carbene structure, wherein the most preferred catalyst is selected from one of the following G1, G2 or G3:

[0023]

[0024] According to an embodiment of the present invention, the reaction is carried out in an inert gas atmosphere, for example, in a nitrogen atmosphere.

[0025] According to an embodiment of the present invention, the molar ratio of monomer MX, DCPD to ruthenium complex catalyst is (2-200000): (2-200000): 1; when the molar ratio of monomer MX, DCPD to catalyst is 100:2000:1, a polymer having a repeating unit number z of 100 and (x+y) of 2000 is obtained; when the molar ratio of monomer MX, DCPD to catalyst is 400:2000:1, a polymer having a repeating unit number z of 400 and (x+y) of 2000 is obtained; and so on.

[0026] According to an embodiment of the present invention, the preparation method of the cross-linked polymer P-MX-DCPD is specifically performed as follows: DCPD and a certain proportion of 7-oxo-2,3-diazanorbornene monomer MX are added to a reaction bottle, and a toluene solution of the G2 catalyst is added under vigorous stirring.

[0027] According to an embodiment of the present invention, during the reaction, depending on the type and proportion of the added monomers, the reaction is stirred for 5-30 minutes, then transferred to a shaped mold, the reaction temperature is controlled to be below 20°C for 2-24 hours, and then reacted at a high temperature for 0.5-2 hours; finally, it is cooled to room temperature and the material is taken out to obtain a recyclable thermosetting material.

[0028] The present invention also provides a method for degrading the P-MX-DCPD thermosetting material, comprising the following steps:

[0029] The cross-linked polymer P-MX-DCPD degrades under acidic conditions.

[0030] According to an embodiment of the present invention, the acidic condition is provided by hydrochloric acid or trifluoroacetic acid. The pH of the acidic condition is <7.0.

[0031] The present invention also provides the use of the cross-linked polymer P-MX-DCPD in preparing a high-strength thermosetting material. The high-strength thermosetting material is mainly used in the fields of construction materials, vehicles, aerospace, electronic and electrical equipment, or sports equipment.

[0032] Beneficial effects

[0033] This application provides a cross-linked polymer based on a class of 7-oxo-2,3-diazanorbornene and DCPD monomers. The resulting cross-linked polymer uses industrially produced raw materials, 7-oxo-2,3-diazanorbornene and DCPD. Therefore, the cross-linked polymer P-MX-DCPD can also be industrially produced, and the production cost is significantly lower than that of existing degradable and recyclable cross-linked polymers. More importantly, the cross-linked polymer of this application is degradable under acidic conditions, and the degradation product can be reused, significantly improving the degradation and recycling difficulties of existing cross-linked polymers.

[0034] Definitions and Explanations of Terms

[0035] The term "C 1-12 “Alkyl” is understood as meaning a linear or branched, saturated, monovalent hydrocarbon radical having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 carbon atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl or their isomers. In particular, said radical has 1, 2, 3 or 4 carbon atoms (“C1-4 alkyl), such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl, sec-butyl, tert-butyl, more particularly, said radicals having 1, 2 or 3 carbon atoms ("C 1-3 "alkyl"), for example methyl, ethyl, n-propyl or isopropyl.

[0036] The term "C 1-12 The C in the alkoxy chain formed by the substitution of 1-6 carbon atoms on the alkyl group by O 1-12 Alkyl has the same meaning as above. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 For P-M1 100 -s-DCPD 1000 TGA curve of .

[0038] Figure 2 For P-M3 200 -s-DCPD 2000 TGA curve of .

[0039] Figure 3 For P-M1 400 -s-DCPD 2000 , P-M1 200 -s-DCPD 2000 , P-M1 100 -s-DCPD 2000 and P-DCPD 2000 DSC curve of .

[0040] Figure 4 For P-M1 400 -s-DCPD 2000 , P-M2 400 -s-DCPD 2000 , P-M3 400 -s-DCPD 2000 and P-M4 400 -s-DCPD 2000 DSC curve of .

[0041] Figure 5 For P-M1 200 -s-DCPD 2000 GPC of the degradation products in hydrochloric acid tetrahydrofuran solution.

[0042] Figure 6 For P-M1 200 -s-DCPD 2000 Schematic diagram of degradation in trifluoroacetic acid in tetrahydrofuran.

[0043] Figure 7 For polymer P-M1200 -s-DCPD 2000 and P-DCPD 2000 photos. DETAILED DESCRIPTION

[0044] The preparation method of the present invention will be described in further detail below with reference to specific examples. It should be understood that the following examples are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection intended by the present invention.

[0045] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the reagents, materials, etc. used in the following examples are all commercially available unless otherwise specified.

[0046] Example 1

[0047]

[0048] Diethyl azodicarboxylate (20mmol, 3.5g) and furan (60mmol, 4.4ml) were placed in a 20ml reaction flask equipped with a magnet and stirred at 25°C for 2.0h until the color changed from orange-red to almost colorless. After removing excess furan by rotary evaporation, no further purification was required. The resulting light yellow or colorless transparent oil was the target product, 7-oxo-2,3-di(ethyl azoacetate)heteronorbornene monomer M1. When the reaction was further amplified, an exothermic phenomenon occurred. An ice-water bath was required to cool the reaction at the beginning, and the prepared monomer was stored in a refrigerator at low temperature. In addition, monomers M2, M3, and M4 were also prepared. The structures of monomers M2, M3, and M4 are shown below:

[0049]

[0050] Example 2

[0051]

[0052] Under room temperature and air conditions, 26.5 g (200 mmol) of DCPD and 2.5 g (10.0 mmol) of 7-oxo-2,3-diazanorbornene monomer M1 were added to the reaction flask, and 0.5 mL of toluene solution prepared by 73 mg of G2 catalyst was added under vigorous stirring. The reaction was continued with stirring for 20 minutes to obtain a thermosetting polymer P-M1. 100 -s-DCPD 2000 Then transfer it to a shaped mold and react at 90℃ for 1.0h. Finally, cool it to room temperature and take out the material, which is the recyclable thermosetting material P-M1. 100 -s-DCPD 2000 .

[0053] In addition, a recyclable thermosetting material P-M1 was prepared 100 -s-DCPD 1000 , and its TGA test results are as follows Figure 1 shown.

[0054] Example 3

[0055] The operation method is the same as that of Example 2, using 26.5g DCPD and 5g 7-oxo-2,3-diazanorbornene monomer M1 to obtain polymer P-M1 200 -s-DCPD 2000 .

[0056] Example 4

[0057] The operation method is the same as that of Example 2, using 26.5g DCPD and 10g 7-oxo-2,3-diazanorbornene monomer M1 to obtain polymer P-M1 400 -s-DCPD 2000 .

[0058] Example 5

[0059] The operation method is the same as that of Example 2, using 26.5g DCPD and 5g 7-oxo-2,3-diazanorbornene monomer M2 to obtain polymer P-M2 200 -s-DCPD 2000 In addition, P-M2 was prepared by increasing the amount of monomer M2 to 10g. 400 -s-DCPD 2000 .

[0060] Example 6

[0061] The operation method is the same as that of Example 2, using 26.5g DCPD and 7.5g 7-oxo-2,3-diazanorbornene monomer M3 to obtain polymer P-M3 200 -s-DCPD 2000 In addition, P-M3 was prepared by increasing the amount of monomer M3 to 15g. 400 -s-DCPD 2000 .

[0062] Example 7

[0063] The operation method is the same as that of Example 2, using 26.5g DCPD and 6.0g 7-oxo-2,3-diazanorbornene monomer M4 to obtain polymer P-M4 400 -s-DCPD 2000 .

[0064] Comparative Example 1

[0065] Under room temperature and air conditions, 26.5 g of DCPD was added to the reaction bottle, and the toluene solution of G2 catalyst was added under vigorous stirring. The reaction was continued for 2 minutes, and then transferred to a shaped mold and reacted at 90 ° C for 1.0 hour to obtain a thermosetting polymer P-DCPD. 2000 Finally, cool it to room temperature and take out the material, which is the thermosetting material P-DCPD. 2000 .

[0066] Example 8

[0067] The thermosetting polymer P-M1 obtained in Example 3 200 -s-DCPD 2000 Soaked in THF, no degradation. Soaked in THF with acid (hydrochloric acid and TFA, respectively), degraded into a soluble polymer, see Figure 5 and Figure 6 The degradation and the obtained polymer were analyzed by GPC, and the molecular weight and distribution of the polymer fragments after degradation were verified to be M n =2.7kDa, PDI=2.3. Therefore, it can be confirmed that the thermosetting polymer P-M1 200 -s-DCPD 2000 The degradation yielded P-DCPD polymer fragments.

[0068] The thermosetting polymer P-DCPD obtained in Comparative Example 1 2000 There was no degradation when soaked in the same THF and acidic THF mentioned above.

[0069] Example 9

[0070] The polymers obtained in Examples 2-7 and Comparative Example 1 were subjected to DSC analysis, which confirmed that their glass transition temperatures could be regulated according to the types and amounts of the added degradable monomers M1, M2, M3 and M4 ( Figure 3 and 4 ).

[0071] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. Cross-linked polymer P-MX-DCPD based on 7-oxo-2,3-diazanorbornene monomer MX and DCPD: in, R 1 , R 2 The same or different, independently selected from C 1-12 Alkyl, C 1-12 Alkoxy chain formed by replacing 1-6 carbon atoms on the alkyl group with O, -(CH2) p C 6-20 Aryl, p is an integer greater than or equal to 0.

2. The cross-linked polymer P-MX-DCPD according to claim 1, wherein The cross-linked polymer P-MX-DCPD structure is shown below: R 1 , R 2 It has the definition of claim 1; (x+y), z are the same or different and are independently an integer of 2-200000.

3. cross-linked polymer P-MX-DCPD according to claim 2, is characterized in that, R 1 , R 2 The same or different, independently selected from C 1-6 Alkyl, C 1-6 Alkoxy chain formed by replacing 1-3 carbon atoms on the alkyl group with O, -(CH2) p C 6-12 Aryl, p is an integer of 1-6; (x+y), z are the same or different and are independently an integer of 10-20,000.

4. The cross-linked polymer P-MX-DCPD according to claim 3, characterized in that R 1 , R 2 is the same and is selected from methyl, ethyl, propyl, isopropyl, benzyl, butyl, isobutyl or tert-butyl.

5. The cross-linked polymer P-MX-DCPD according to any one of claims 1 to 4, characterized in that The cross-linked polymer P-MX-DCPD has the following structure: wherein (x+y) and z are the same or different and are independently 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 1000 or 2000.

6. The method for preparing the cross-linked polymer P-MX-DCPD according to any one of claims 1 to 4, characterized in that: The steps include: 7-Oxo-2,3-diazanorbornene monomer MX and DCPD undergo cross-linking polymerization reaction in the presence of ruthenium complex catalyst.

7. The preparation method according to claim 6, characterized in that The cross-linked polymer reaction is:

8. The method for degrading the cross-linked polymer P-MX-DCPD according to any one of claims 1 to 5, characterized in that: The steps include: The cross-linked polymer P-MX-DCPD degrades under acidic conditions.

9. The degradation method according to claim 8, characterized in that: The acidic condition is provided by hydrochloric acid or trifluoroacetic acid.

10. Use of the cross-linked polymer P-MX-DCPD according to any one of claims 1 to 5 in the preparation of a high-strength thermosetting material, wherein the high-strength thermosetting material is mainly used in the fields of construction materials, vehicles, aerospace, electronic and electrical equipment, or sports equipment.

Images