Mechanically adjustable polydicyclopentadiene / carene copolymers and methods for making same

Abstract

The application relates to a polydicyclopentadiene / caryophyllene copolymer with adjustable mechanical properties and a preparation method thereof, and belongs to the technical field of polymer materials. The copolymer is prepared by a front-end ring-opening metathesis polymerization method through dicyclopentadiene and caryophyllene monomers. By changing the amount of caryophyllene, the crosslinking degree of polydicyclopentadiene can be adjusted, so that materials with different mechanical properties can be obtained. With the increase of the amount of caryophyllene, the prepared material can be changed from a hard thermosetting plastic to a soft elastomer, so that the mechanical properties of the material can be adjusted. The raw material components used in the application are all liquids and can be mutually soluble in any proportion. The obtained material has adjustable mechanical properties and can meet the demand of polydicyclopentadiene in different application scenarios. Meanwhile, caryophyllene is a biobased source and belongs to renewable resources. The copolymerization of caryophyllene and dicyclopentadiene through the front-end polymerization method is not only easy to operate, but also has low energy consumption, and meets the requirements of low carbon environmental protection and sustainable development.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a polydicyclopentadiene / caryophyllene copolymer with adjustable mechanical properties and its preparation method. Background Technology

[0002] Dicyclopentadiene (DCPD) is a byproduct of steam cracking during ethylene production and can be synthesized into polydicyclopentadiene (PDCPD) via ring-opening metathesis polymerization. PDCPD is a thermosetting engineering plastic with excellent mechanical properties, thermal stability, and chemical resistance, playing an increasingly important role in high-tech fields such as electronics, aerospace, automotive, and flexible electronic circuits. Currently, PDCPD is mainly processed through reaction injection molding (RIM), resin transfer molding (RTM), and vacuum-assisted resin transfer molding (VTRTM). Front-end polymerization (FP) is a promising curing strategy that significantly reduces the manufacturing burden by using the polymerization enthalpy to provide energy for material synthesis. In front-end polymerization, solutions of monomers and potential initiators are locally heated until the initiator is activated to polymerize the monomers, generating heat from the polymerization to further drive the reaction. The auto-activation process generates a propagating reaction wave, rapidly converting available monomers into polymers, offering advantages such as fast reaction speed, energy saving, and continuous reaction process.

[0003] As the application fields of PDCPD continue to expand, its shortcomings of quasi-static mechanical properties and lack of ductility have gradually become apparent. In order to make up for this shortcoming, Quentin Beuguel et al. (Upgrading Toughness and the Glass Transition Temperature of Polydicyclopentadiene upon Addition of Styrene–Ethylene–Butylene–Styrene Thermoplastic Elastomer[J].ACS Applied PolymerMaterials.2022,4(4):2251–2255) used styrene-ethylene-butene-styrene thermoplastic elastomer to toughen PDCPD. However, this method requires the elastomer to be dissolved in DCPD raw material first, and the polymerization reaction can only be carried out after 48 hours of dissolution. This method has the disadvantages of inhomogeneity and long dissolution time, which is not conducive to industrial production and large-scale manufacturing. Gao Feifei et al. (The Functionalized UiO-66 Engineering for the Synergistic Enhancement of Mechanical Properties of Polydicyclopentadiene Nanocomposites[J]. Journal of Inorganic and Organometallic Polymers and Materials, 2023, 33(2):328-336) prepared composite materials with inorganic nanoparticle fillers and DCPD. In order to improve the interaction and compatibility between the filler and the resin, the filler needs to be modified, which is a relatively complicated operation, and the issues of dispersibility and uniformity still need to be considered.

[0004] Against this backdrop, developing a simple, effective, and rapidly prepared method with tunable mechanical properties is of great significance. Therefore, this invention provides a mechanically tunable polydicyclopentadiene / caryophyllene copolymer and its rapid preparation method. Summary of the Invention

[0005] Based on rapid polymerization molding, this invention imparts adjustable mechanical properties to the material, providing a polydicyclopentadiene / caryophyllene copolymer with adjustable mechanical properties and its rapid preparation method, thereby solving the problems of polydicyclopentadiene material having good rigidity but insufficient toughness, and traditional processing methods requiring large equipment and high curing temperatures and long curing times.

[0006] The mechanically tunable polydicyclopentadiene / caryophyllene copolymer of this invention is prepared by using dicyclopentadiene and caryophyllene as raw materials and employing a ruthenium-based catalyst via a front-end ring-opening metathesis polymerization method. This polydicyclopentadiene / caryophyllene copolymer is a thermosetting material, and its general structural formula is as follows:

[0007]

[0008] Where x, y, and z are positive integers;

[0009] The present invention discloses a method for preparing a polydicyclopentadiene / caryophyllene copolymer with adjustable mechanical properties. The method involves mixing dicyclopentadiene and caryophyllene monomers, degassing the mixture for 10–30 minutes, adding a catalyst, and mixing thoroughly. The monomer and catalyst mixture is then locally heated using a front-end triggering device (heating temperature range of 80–300°C) until the catalyst is activated to trigger local polymerization. The heat generated during polymerization further drives the reaction. The automatic activation process generates a propagating exothermic reaction wave that rapidly converts unreacted monomers into polymers. After cooling to room temperature, the polymer is obtained as described in this invention.

[0010] Preferably, dicyclopentadiene is a solid at room temperature and needs to be heated and melted before use, while after adding caryophyllene, the mixture remains liquid at room temperature, and the two monomers are miscible in any proportion.

[0011] Furthermore, the raw material monomers are measured by volume and 100%, wherein the volume content of dicyclopentadiene ranges from 20% to 95%, and the remainder is caryophyllene.

[0012] Furthermore, the catalyst is a ruthenium-based catalyst, preferably a Grubbs series catalyst, such as Grubbs 2 catalyst (commercially available and readily available for purchase). The catalyst can be formulated using common organic reagents such as dichloromethane, chloroform, and cyclohexylbenzene, or it can be dissolved using caryophyllene. The amount of catalyst used is 0.04–0.1 mol% of all monomers.

[0013] Furthermore, the aforementioned front-end triggering device can be a thermocouple wire, a soldering iron, a heating table, or other similar device, which can be quickly removed from the heat source after triggering localized aggregation.

[0014] Furthermore, the preparation method can be carried out in a mold with a certain shape, and the mold material can be one or a combination of silicone, glass, aluminum plate, steel plate, and polytetrafluoroethylene.

[0015] Furthermore, in the preparation process of the copolymer, inorganic materials can be added as fillers, such as chopped carbon fibers, basalt fibers, carbon powder, graphite, silica, montmorillonite, and diatomaceous earth. Natural materials such as cellulose and hemp fibers can also be added as fillers. The fillers do not affect the front-end polymerization effect and play a role in filling and reinforcing modification. The amount of filler used is 0.1% to 30% of the combined mass of dicyclopentadiene and caryophyllene monomers, and more specifically, 3% to 10%.

[0016] The copolymer prepared according to the method described above can have its crosslinking degree adjusted by changing the amount of caryophyllene monomer, achieving adjustable tensile strength from 0.05 to 57.12 MPa and elongation at break from 14.08 to 1160.15%. This transforms the prepared polydicyclopentadiene / caryophyllene copolymer material from a rigid thermosetting plastic to a soft elastomer, meeting diverse application needs such as shock-absorbing parts, cushioning materials, and sealing materials, and thus enabling its application in machinery manufacturing, transportation, and chemical industries. This opens a new path for the application of polydicyclopentadiene materials. Furthermore, caryophyllene is a bio-based, renewable resource. Its copolymerization with dicyclopentadiene via front-end polymerization is not only easy to operate but also consumes less energy, meeting the requirements of low-carbon, environmentally friendly, and sustainable development.

[0017] Meanwhile, this invention employs a front-end polymerization method for curing, in which a self-propagating exothermic reaction wave transforms the liquid monomer into a fully cured polymer. Polymerization kinetics can be precisely controlled at both room and high temperatures, allowing a stable monomer solution to be converted into a fully cured polymer within minutes. Compared to traditional oven or autoclave curing methods, this reduces energy requirements and curing time by several orders of magnitude. The resulting polymers or composites exhibit mechanical properties similar to those obtained through conventional curing. This curing strategy significantly improves the production efficiency of high-performance polymers and composites and can be widely applied in many industries. Attached Figure Description

[0018] Figure 1 Stress-strain curves of copolymers (1) to (7) in Example 1. As can be seen from the figure, the mechanical properties of the copolymers can be adjusted with the change of the amount of caryophyllene.

[0019] Figure 2 Photograph of the front-end polymerization process of the raw materials in Example 3.

[0020] Figure 3 Photograph of the front-end polymerization process of the raw materials in Example 4. Detailed Implementation

[0021] The present invention will be described below through specific embodiments, but is not limited thereto.

[0022] Example 1

[0023] Table 1: Amount data of each raw material used in Example 1

[0024]

[0025]

[0026] Weigh the reactants corresponding to the serial numbers (1) to (7) in Table 1 above, mix them, degas for 30 minutes, then add the catalyst, mix evenly, and pour into the mold. Finally, use a soldering iron to trigger the front end, so that the monomer and initiator solution is locally heated until the initiator is activated to carry out monomer polymerization. Then, the heat generated during polymerization further drives the reaction. The automatic activation process generates a propagating reaction wave, which rapidly converts the unreacted monomer into polymer. After the mold cools down, the material can be removed.

[0027] Example 2

[0028] Table 2: Amount data of each raw material used in Example 2

[0029]

[0030] The nano-silica was dried in an oven at 60°C for 8 hours. Then, the reactants and fillers corresponding to the serial numbers (1) to (4) in the table above were weighed, mixed, and degassed for 30 minutes. Subsequently, the catalyst was added, mixed evenly, and poured into a mold. Finally, the solution of monomer and initiator was locally heated by a soldering iron until the initiator was activated to polymerize the monomer. The heat generated during the polymerization further drove the reaction. The automatic activation process generated a propagating reaction wave, which rapidly converted the unreacted monomer into polymer. After the mold cooled, the material was removed.

[0031] Example 3

[0032] To more intuitively observe the reaction rate of the front-end polymerization, the reaction raw materials can be prepared according to the steps of Example 1. Here, we take the fourth group of Example 1 as an example. The reactants are placed in a test tube, and an electric soldering iron is used as the triggering tool for the front-end polymerization. The polymerization reaction process is recorded by a digital camera, and the reaction rate of the front-end polymerization can be observed.

[0033] Example 4

[0034] To observe the effect of the filler on the reaction rate of the front-end polymerization, the reaction raw materials can be prepared according to the steps of Example 2. Here, the fourth group of Example 2 is selected as an example. The reactants are placed in a test tube, and an electric soldering iron is used as the triggering tool for the front-end polymerization. The polymerization reaction process is recorded by a digital camera, and the reaction rate of the front-end polymerization can be observed.

[0035] Comparing the results of Example 3 and Example 4, it can be seen that the copolymer with added silica filler has a slightly lower front-end polymerization rate, but it can still complete polymerization within 5 minutes. Therefore, the filler does not affect the effect of front-end polymerization.

[0036] Example 5

[0037] The materials obtained in Examples 1 (1) to (7) were used to make tensile specimens, and their mechanical properties were tested. Figure 3 It can be observed that the copolymers prepared according to the above method can achieve tensile strengths of 0.05 to 57.12 MPa and elongation at break of 14.08 to 1160.15% by changing the amount of caryophyllene monomer, as shown in Table 3.

[0038] Table 3: Mechanical property data of materials in Example 1

[0039]

[0040] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. Those skilled in the art can make corresponding changes and substitutions based on the technical solutions and inventive concepts of the present invention, and any modifications or substitutions resulting in the same performance or application should be considered within the scope of protection of the present invention.

Claims

1. A polydicyclopentadiene / caryophyllene copolymer with adjustable mechanical properties, characterized in that: This polydicyclopentadiene / caryophyllene copolymer is a thermosetting material, and its general structural formula is shown below. Where x, y, and z are positive integers.

2. The method for preparing a mechanically tunable polydicyclopentadiene / caryophyllene copolymer according to claim 1, characterized in that: The process involves mixing dicyclopentadiene monomer and caryophyllene monomer, degassing for 10–30 minutes, adding a catalyst, mixing thoroughly, and then using a front-end triggering device to locally heat the monomer and catalyst mixture until the catalyst is activated to trigger local polymerization. The heat generated during polymerization further drives the reaction, and the automatic activation process generates a propagating exothermic reaction wave that rapidly converts unreacted monomers into polymers. After cooling to room temperature, the polymer is obtained.

3. The method for preparing a mechanically tunable polydicyclopentadiene / caryophyllene copolymer as described in claim 2, characterized in that: Dicyclopentadiene is a solid at room temperature and needs to be melted by heating before use; the dicyclopentadiene monomer and caryophyllene monomer are measured by volume and 100%, of which the volume content of dicyclopentadiene ranges from 20% to 95%, and the remainder is caryophyllene.

4. The method for preparing a mechanically tunable polydicyclopentadiene / caryophyllene copolymer as described in claim 2, characterized in that: The catalyst is a ruthenium-based catalyst, which is dissolved in dichloromethane, chloroform, cyclohexylbenzene or caryophyllene. The amount of catalyst used is 0.04 to 0.1% of the sum of the molar amounts of dicyclopentadiene and caryophyllene monomers.

5. The method for preparing a mechanically tunable polydicyclopentadiene / caryophyllene copolymer as described in claim 2, characterized in that: The front-end triggering device is a thermocouple wire, soldering iron, or heating table. After local polymerization is triggered, the front-end triggering device can be quickly removed. The heating temperature range of the front-end triggering device is 80 to 300°C.

6. The method for preparing a mechanically tunable polydicyclopentadiene / caryophyllene copolymer as described in claim 2, characterized in that: In the preparation of the copolymer, inorganic or natural materials are added as fillers. The inorganic materials are one or more of chopped carbon fibers, basalt fibers, carbon powder, graphite, silica, montmorillonite, and diatomaceous earth. The natural materials are one or more of cellulose and hemp fibers. The filler content is 0.1% to 30% of the sum of the mass of dicyclopentadiene and caryophyllene monomers.

7. The method for preparing a mechanically tunable polydicyclopentadiene / caryophyllene copolymer as described in claim 6, characterized in that: The filler dosage is 3 to 10% of the combined mass of dicyclopentadiene and caryophyllene monomers.

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