A photodegradable recycled polydicyclopentadiene thermoset and method of making the same

Abstract

The application discloses a kind of photodegradable recycled polydicyclopentadiene thermosetting material and preparation method thereof, and the selected is dicyclopentadiene (DCPD) monomer and photodegradable cyclic internal olefin monomer is prepared by metathesis copolymerization method, wherein, photodegradable cyclic internal olefin monomer is cyclic internal olefin monomer containing o-nitrobenzyl (o-NB) functional group, in addition, the material after degradation can be further with DCPD by metathesis method to prepare thermosetting material, the mechanical properties of the obtained material are equivalent to original material. Therefore, the polydicyclopentadiene thermosetting material prepared in the application is a new type of photodegradable recycled thermosetting material.

Description

Technical Field

[0001] This invention belongs to the field of polymer material synthesis technology, specifically relating to a method for preparing a novel biodegradable and recyclable polydicyclopentadiene thermosetting material by metathesis copolymerization of an organic compound containing an o-nitrobenzyl (o-NB) functionalized cyclic intraolefin monomer and DCPD monomer. Background Technology

[0002] Thermosetting materials are widely used in various fields, including military and civilian applications, due to their high strength and durability. However, the increasing use of these materials inevitably leads to a large amount of difficult-to-manage and recycle solid waste due to their insoluble and non-melting properties. Furthermore, the amount of waste is increasing dramatically with the rapid increase in usage. Because the cross-linked structure of thermosetting materials is permanently cross-linked and generally does not change or break, it cannot be further processed or reused. Most of this waste is disposed of through incineration or landfill, causing serious environmental problems and placing a significant burden on the natural environment.

[0003] To address this issue, numerous studies on the degradation and recycling of thermosetting materials have been reported. These include the synthesis of a series of silicon-oxygen monomers by Professor Johnson of MIT and Professor Chen Changle of the University of Science and Technology of China, which were metathesis copolymerized with dimercyclopentadiene (DCPD) monomers to form a biodegradable and recyclable thermosetting material. However, the synthesis of these monomers is quite difficult and not suitable for large-scale production. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to obtain a thermosetting material that can be photodegraded and recycled by simply preparing a cyclic endopeptide monomer containing o-nitrobenzyl (o-NB) functionalization and a dimer cyclopentadiene monomer through metathesis copolymerization thermosetting. This type of thermosetting material has excellent and stable mechanical properties, and after photodegradation, the fragmented polymer compound obtained by this material can still be used to prepare a thermosetting material with certain mechanical properties by continuing to metathesis copolymerize thermosetting with DCPD monomer.

[0005] This invention provides a photodegradable and recyclable polydicyclopentadiene thermosetting material, wherein the polydicyclopentadiene thermosetting material is a compound with structural formula (I).

[0006] Equation (I): In the structural formula, c represents the number of double bonds in dicyclopentadiene that are both open, and is a positive integer; fc represents the number of double bonds in dicyclopentadiene that are open, and is a positive integer; x represents the number of monomers inserted that are functionalized with o-nitrobenzyl (o-NB), and is a positive integer.

[0007] Preferably, the structure of the cyclic intraolefin monomer M containing o-nitrobenzyl (o-NB) functionalization used in the copolymerization of the compound of formula (I) is as follows:

[0008] .

[0009] The present invention provides a method for preparing a cyclic intraolefin monomer M containing o-nitrobenzyl (o-NB) functionalization, comprising: reacting a compound of formula (II) and a compound of formula (III) to obtain a cyclic intraolefin monomer M containing o-nitrobenzyl (o-NB) functionalization.

[0010] Formula (II); Formula (III); .

[0011] This invention also provides a method for preparing a compound of formula (I): a dicyclopentadiene (DCPD) monomer and a cyclic intraolefin monomer M containing o-nitrobenzyl (o-NB) functionalization are reacted via a metathesis reaction to obtain a photodegradable and recyclable polydicyclopentadiene thermosetting material.

[0012]

[0013] In this invention, the groups of substituents with the same number in the molecule can be the same or different.

[0014] Preferably, the preparation of the cyclic lactone monomer containing o-nitrobenzyl functionalization includes the following specific steps:

[0015] The compound of structure (III) was dissolved together with triethylamine in dichloromethane solvent at 0 °C, and then the compound of structure (II) was added dropwise. The reaction was carried out at room temperature for 0.5-3 h. The triethylamine hydrochloride was removed by filtration and the intermediate compound P was concentrated. Then, the intermediate compound P was dissolved in dichloromethane solvent, and GII catalyst was added. The reaction was carried out at 100-200 °C for 0.5-3 h. The target monomer product M was obtained by vacuum distillation, which is a cyclic intraolefin monomer containing o-nitrobenzyl functionalization.

[0016] The molar ratio of the compound with structure (II), the compound with structure (III), and triethylamine is 1:(2-3):(2-3).

[0017] The present invention does not limit the vacuum distillation method described herein; any method known to those skilled in the art is acceptable.

[0018] This invention provides a method for preparing photodegradable and recyclable polydicyclopentadiene thermosetting material in situ via metathesis. The preferred method involves dissolving a metathesis catalyst, Grubbs second-generation catalyst (GII), in a small amount of dichloromethane in a glass sample vial. The solvent is then removed under vacuum. Dipolycyclopentadiene and a cyclic intraolefin monomer functionalized with o-nitrobenzyl (o-NB) are added, mixed thoroughly, and poured into a mold. The mixture is then cured at 100-200°C for 0.5-3 hours, and cooled to room temperature to obtain the desired thermosetting material.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This invention provides a monomer containing o-nitrobenzyl (o-NB) functionalization. The structure contains o-NB functional groups, which introduce photodegradable motifs into the main chain of polydicyclopentadiene, causing the thermosetting polydicyclopentadiene material to degrade into soluble fragments under light. Compared with chemical degradation, photodegradation is cleaner, greener, and consumes less energy.

[0021] 2. This invention provides a class of o-nitrobenzyl (o-NB) functionalized cyclic intraolefin monomers. In the olefin metathesis polymerization system, compared with diene monomers, cyclic olefin monomers have higher polymerization efficiency. Therefore, the thermosetting materials prepared have better mechanical properties. The tensile strength of diene thermosetting materials (45-60 MPa) is lower than that of cyclic olefin thermosetting materials (>60 MPa).

[0022] 3. Compared with traditional photodegradation, this invention realizes the recycling of photodegradation products, thereby enabling the closed-loop recycling of experimental photodegradable polymer materials and providing a new approach for the closed-loop degradation and recycling of polydicyclopentadiene thermosetting materials. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a photograph of the photodegradable and recyclable thermosetting material in Embodiment 1 of the present invention;

[0025] Figure 2 These are before-and-after comparison images of the photodegradable thermosetting material in Example 1 of this invention.

[0026] Figure 3 The above are the proton NMR spectra of the photodegradable thermosetting material before and after degradation in Example 1 of this invention.

[0027] Figure 4 This is a comparison of tensile tests on the reuse of photodegradable thermosetting material recycled materials in Example 1 of the present invention;

[0028] PDCPD: Thermosetting material obtained without the addition of degradation and recycling products of dicyclopentadiene; PDCPD-2.5%-recycle: Thermosetting material obtained with a molar ratio of degradation and recycling products to dicyclopentadiene of 2.5%; PDCPD-5%-recycle: Thermosetting material obtained with a molar ratio of degradation and recycling products to dicyclopentadiene of 5.0%.

[0029] Figure 5 Tensile test comparison between the photodegradable thermosetting material in Example 1 of this invention and the PDCPD blank sample;

[0030] PDCPD: thermosetting material derived from dicyclopentadiene; PDCPD-2%-M: thermosetting material containing 2% molar ratio of cyclic endopeptide monomer M with o-nitrobenzyl (o-NB) functionalization to dicyclopentadiene;

[0031] Figure 6 The 1H NMR spectrum of intermediate compound P in Example 1 of this invention;

[0032] Figure 7 The 1H NMR spectrum of the cyclic intraolefin monomer M containing o-nitrobenzyl (o-NB) functionalization in Example 1 of this invention;

[0033] Figure 8 The infrared test image is of the photodegradable and recyclable thermosetting material in Embodiment 1 of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] Step 1: Preparation of cyclic lactone monomer M functionalized with o-nitrobenzyl (o-NB)

[0037]

[0038] Compound III (20.0 mmol) and triethylamine (30.0 mmol) were dissolved in 60 mL of dichloromethane. The temperature was lowered to 0 °C, and then a dichloromethane solution (1 mol / L) of compound II (10.0 mmol) was slowly added dropwise. After the addition was complete, the reaction was allowed to return to room temperature and continue for 2 h. After the reaction was complete, the triethylamine hydrochloride was removed by filtration, and the mixture was concentrated to obtain intermediate compound P. Intermediate compound P (10.0 mmol) was dissolved in 30 mL of dichloromethane, and the filtrate was concentrated. Then, GII catalyst (0.01 mmol) was added, and the reaction was carried out at 100 °C for 1 h. The target monomer product M was obtained by vacuum distillation.

[0039] Step 2: Preparation of thermoset materials

[0040]

[0041] In a glass sample vial, the metathesis catalyst GII (0.002 mmol, 3.4 mg) was dissolved in a small amount of dichloromethane. The solvent was then removed under vacuum. DCPD (40 mmol, 5.3 g) and the cyclic lactone monomer M (0.8 mmol, 0.4 g) functionalized with o-nitrobenzyl (o-NB) were added. After thorough mixing, the mixture was poured into a mold and cured at 140 °C for 30 minutes. After cooling to room temperature, the desired polydicyclopentadiene thermosetting material was obtained. (See [link to relevant documentation]). Figure 1 It is a transparent, photodegradable, and recyclable thermosetting material.

[0042] Example 2

[0043] The difference between this embodiment and Embodiment 1 is that:

[0044] In a glass sample vial, the metathesis catalyst GII (0.002 mmol, 3.4 mg) was dissolved in a small amount of dichloromethane. The solvent was then removed under vacuum. DCPD (80 mmol, 10.6 g) and a cyclic endopeptide monomer M (0.8 mmol, 0.4 g) functionalized with o-nitrobenzyl (o-NB) were added. After mixing thoroughly, the mixture was poured into a mold and cured at 200 °C for 30 minutes. After cooling to room temperature, the desired polydicyclopentadiene thermosetting material was obtained. This material is transparent, photodegradable, and recyclable.

[0045] Example 3

[0046] The difference between this embodiment and Embodiment 1 is that:

[0047] In a glass sample vial, the metathesis catalyst GII (0.002 mmol, 3.4 mg) was dissolved in a small amount of dichloromethane. The solvent was then removed under vacuum. DCPD (80 mmol, 10.6 g) and the cyclic endopeptide monomer M (0.8 mmol, 0.4 g) functionalized with o-nitrobenzyl (o-NB) were added. After mixing thoroughly, the mixture was poured into a mold and cured at 100 °C for 60 minutes. After cooling to room temperature, the desired polydicyclopentadiene thermosetting material was obtained. This material is transparent, photodegradable, and recyclable.

[0048] Example 4

[0049] The difference between this embodiment and Embodiment 1 is that:

[0050] In a glass sample vial, the metathesis catalyst GII (0.002 mmol, 3.4 mg) was dissolved in a small amount of dichloromethane. The solvent was then removed under vacuum. DCPD (80 mmol, 10.6 g) and the thermosetting material recycled dicyclopentadiene (2 mmol, 0.3 g) were then added. After mixing thoroughly, the mixture was poured into a mold and cured at 140 °C for 30 minutes. After cooling to room temperature, the upgraded recycled dicyclopentadiene thermosetting material was obtained.

[0051] Example 5

[0052] The difference between this embodiment and Embodiment 1 is that:

[0053] In a glass sample vial, the metathesis catalyst GII (0.002 mmol, 3.4 mg) was dissolved in a small amount of dichloromethane. The solvent was then removed under vacuum. DCPD (80 mmol, 10.6 g) and the thermosetting material recycled dicyclopentadiene (4 mmol, 0.8 g) were then added. After mixing thoroughly, the mixture was poured into a mold and cured at 140 °C for 30 minutes. After cooling to room temperature, the upgraded recycled dicyclopentadiene thermosetting material was obtained.

[0054] Test Example 1: Degradation and Recycling of Thermosetting Materials

[0055] The thermosetting material prepared in Example 1 was pulverized and placed in a glass bottle. A chloroform-methanol mixture was added, and after irradiation with an ultraviolet lamp (80 W, 365 nm) for 6 hours, the material was completely degraded and dissolved in the solution. The solution was concentrated, methanol was added to precipitate the polymer, and the polymer was dried. The test results are as follows. Figure 3 As shown.

[0056] Test Example 2: Mechanical Properties of Thermosetting Materials

[0057] According to the standard test method ASTM 638, the specimen was a dumbbell-shaped strip 50 mm long, 4 mm wide (at its narrowest point), and 2.0 mm thick. The stress-strain test was conducted at room temperature at a speed of 10 cm / min, and the test results are as follows: Figure 5 As shown.

[0058] In summary:

[0059] Examples 1-3 investigate the preparation of photodegradable polydicyclopentadiene thermosetting materials with o-nitrobenzyl (o-NB) functionalization using different catalyst equivalences and heating times.

[0060] Figure 1 The image shows the preparation of a transparent thermosetting polydicyclopentadiene containing o-nitrobenzyl (o-NB) functionalization, which exhibits good light transmittance. Figure 2 Introducing photodegradable building blocks into the main chain of polydicyclopentadiene allows the thermosetting polydicyclopentadiene material to degrade into soluble fragments under light, laying the foundation for the recycling of photodegradable thermosetting materials. Figure 3 The 1H NMR spectrum of the photodegradation products clearly shows the structure of the photodegradation products and verifies the feasibility of the scheme. Figure 4 For the recycling of photodegradation products, tensile tests showed that the thermosetting materials prepared from the recycled materials had mechanical properties comparable to those of the original materials. Figure 5 Tensile tests show that in the olefin metathesis polymerization system, the polymerization efficiency of cyclic olefin monomers is higher, and the prepared thermoset materials have better mechanical properties. The tensile strength of the original thermoset material is 60 MPa, while the tensile strength of the cyclic olefin provided by this invention is 65 MPa. Figure 6 and Figure 7 The proton NMR spectra of the synthetic intermediate and the ring-shaped monomer were characterized to clarify the monomer structures involved in the scheme. Figure 8 Infrared spectral characterization of polydicyclopentadiene thermosetting materials containing o-nitrobenzyl (o-NB) functionalization was performed. The spectrum showed obvious peaks of carbonyl and nitro functional groups, further clarifying the structure of the thermosetting materials.

[0061] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a photodegradable and recyclable polydicyclopentadiene thermosetting material, characterized in that, Includes the following steps: Dicyclopentadiene monomers and cyclic intracyclic olefin monomers undergo a metathesis reaction with a second-generation Grubbs catalyst to yield a photodegradable and recyclable polydicyclopentadiene thermosetting material. The reaction formula is as follows: In the structural formula, c represents the number of double bonds in dicyclopentadiene that are both open, and is a positive integer; fc represents the number of double bonds in dicyclopentadiene that are open, and is a positive integer; x represents the number of monomers inserted that are functionalized with o-nitrobenzyl, and is a positive integer.

2. The method for preparing a photodegradable and recyclable polydicyclopentadiene thermosetting material according to claim 1, characterized in that, The method for preparing the cyclic lactone monomer containing o-nitrobenzyl functionalization includes: The reaction of compounds of formula (II) and formula (III) yields cyclic intraolefin monomers containing o-nitrobenzyl functionalization; Formula (II): ; Formula (III): .

3. The method for preparing a photodegradable and recyclable polydicyclopentadiene thermosetting material according to claim 2, characterized in that, The preparation of the cyclic lactone monomer containing o-nitrobenzyl functionalization includes the following specific steps: The compound of structure (III) was dissolved together with triethylamine in dichloromethane solvent at 0 °C, and then the compound of structure (II) was added dropwise. The reaction was carried out at room temperature for 0.5-3 h. The triethylamine hydrochloride was removed by filtration and the intermediate compound P was concentrated. Then, the intermediate compound P was dissolved in dichloromethane solvent, and GII catalyst was added. The reaction was carried out at 100-200 °C for 0.5-3 h. The target monomer product M was obtained by vacuum distillation, which is a cyclic intraolefin monomer containing o-nitrobenzyl functionalization.

4. The method for preparing a photodegradable and recyclable polydicyclopentadiene thermosetting material according to claim 3, characterized in that, The molar ratio of the compound with structure (II), the compound with structure (III), and triethylamine is 1:(2-3):(2-3).

5. The method for preparing a photodegradable and recyclable polydicyclopentadiene thermosetting material according to claim 1, characterized in that, The specific steps include the following: In a glass sample vial, the Grubbs second-generation catalyst is dissolved in dichloromethane, the solvent is then removed by vacuum, and then dimercyclopentadiene monomer and cyclic intraolefin monomer containing o-nitrobenzyl functionalization are added. After mixing evenly, the mixture is poured into a mold and cured at 100-200℃ for 0.5-3 hours. After cooling to room temperature, the desired thermosetting material is obtained.

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