Two-component liquid crystal polymer resin material and preparation method thereof

Abstract

The invention relates to a two-component liquid crystal polymer resin material and a preparation method thereof, and belongs to the technical field of intelligent polymer materials. The obtained liquid crystal polymer resin has the characteristics of simple preparation steps and rapid reaction, and a liquid crystal elastomer sample can be prepared only by mixing two components for reaction and then stretching and illuminating without removing a solvent. And the whole process only needs several hours at the fastest speed, so that the production efficiency is greatly improved. The two-component liquid crystal polymer resin material comprises a component A and a component B, the component A is a liquid crystal oligomer which is prepared by reacting a diacrylate-terminated liquid crystal monomer, a dithiol chain extender and a catalyst; the component B comprises a dithiol chain extender, a cross-linking agent, a catalyst and a photoinitiator.

Description

Technical Field

[0001] The invention belongs to the technical field of intelligent polymer materials, and specifically relates to a two-component liquid crystal polymer resin material and a preparation method thereof. Background Art

[0002] Smart materials are a type of functional materials that can undergo macroscopic deformation when external conditions change. They have been widely used in the fields of deformable structures, intelligent robots, etc., including traditional shape memory alloys, shape memory polymers, dielectric elastomers, smart hydrogels, liquid crystal elastomers, etc. Compared with traditional smart materials, liquid crystal elastomers have the advantages of anisotropic contraction, strong deformation ability, fast response speed, mild stimulation conditions, and good reversible cycle performance. In addition, liquid crystal elastomers can achieve different deformation modes through molding, scraping, 3D printing and other processing and manufacturing methods, which meets the multi-faceted needs of the intelligent field for high-performance smart soft materials, has attracted widespread attention, and has broad development potential.

[0003] Liquid crystal elastomers are generally prepared by methods such as liquid crystal box orientation curing, mechanical stretching, electrostatic spinning, extrusion 3D printing, etc. The most widely used method for preparing liquid crystal elastomer devices is to use a method of curing after mechanical stretching. However, this method requires adding a solvent to the liquid crystal monomer solid powder and heating it to high temperature to dissolve it, and then reacting with other components. After the reaction is completed, the solvent needs to be heated and removed in an oven. The reaction steps are cumbersome and time-consuming. It takes 3 days to prepare an oriented liquid crystal elastomer sample. Chinese patent CN115710354B discloses a method of dissolving liquid crystal monomers, crosslinking agents and chain extenders in an organic solvent, mixing them evenly, continuing to add ionic liquids and mixing them evenly to form a mixed solution, and then initiating and performing a crosslinking reaction. This method can produce a liquid crystal elastomer composite film with excellent mechanical properties. However, the solvent needs to be removed during the film preparation process, the preparation cycle is long, and it is not suitable for 3D printing. CN114851551B prepares liquid crystal elastomer 3D printing ink by mixing liquid crystal macromolecular monomers with photoinitiators, crosslinking agents, thermal initiators and thiols at room temperature, melting and reacting. However, the reaction time is long, requiring 3-48 hours to ensure complete reaction, which affects the printing efficiency. CN113977943A discloses a method of selectively curing the molding material by ultraviolet light scanning after extruding and depositing the liquid crystal elastomer material, so as to control the total ultraviolet light irradiation dose received by different regions, thereby controlling the crosslinking density of different regions of the material. This method focuses on the later printing process and does not involve the preparation of the material. Summary of the invention

[0004] In view of the above problems, the present invention provides a two-component liquid crystal polymer resin material and a preparation method thereof. The liquid crystal polymer resin obtained by the present invention has the characteristics of simple preparation steps and fast reaction. To prepare a liquid crystal elastomer sample, it is only necessary to mix the two components and then stretch and illuminate them without removing the solvent. At the same time, the entire process only takes a few hours at the fastest (the fastest is as short as 3 hours under laboratory conditions), which greatly improves the production efficiency.

[0005] The present invention provides a two-component liquid crystal polymer resin material, comprising component A and component B;

[0006] Wherein, component A is a liquid crystal oligomer, which is prepared by reaction of a diacrylate-terminated liquid crystal monomer, a dithiol chain extender and a catalyst;

[0007] Component B includes a dithiol chain extender, a crosslinker, a catalyst and a photoinitiator.

[0008] Optionally, the acrylic acid ester liquid crystal monomer is 1,4-bis-[4-(3-acryloxypropoxy)benzoyloxy]-2-methylbenzene, 1,4-bis-[4-(6-acryloxyhexyloxy)benzoyloxy]-2-methylbenzene or 4-((6-(acryloxy)hexyl)oxy)phenyl 4-((6-(acryloxy)hexyl)oxy)benzoate.

[0009] Optionally, the dithiol chain extender is 3,6-dioxa-1,8-octanedithiol or 1,3-propanedithiol or 1,5-pentanedithiol.

[0010] Optionally, the catalyst is di-n-propylamine.

[0011] Optionally, the cross-linking agent is pentaerythritol tetrakis(3-mercaptopropionate).

[0012] Optionally, the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

[0013] Optionally, the molar ratio of the dithiol chain extender to the cross-linking agent in component B is 0.5 to 6:1.

[0014] Another aspect of the present invention further discloses a method for preparing a two-component liquid crystal polymer resin material, which is used to prepare the aforementioned two-component liquid crystal polymer resin material, and the specific steps are:

[0015] Step 1, dissolving a diacrylate-terminated liquid crystal monomer in an organic solvent, adding a dithiol chain extender and a catalyst, and stirring the mixture at room temperature to obtain a liquid crystal oligomer solution; removing the organic solvent from the solution to obtain component A;

[0016] Step 2, mixing the dithiol chain extender, the cross-linking agent, the catalyst and the photoinitiator to obtain component B;

[0017] Step 3, mix component A and component B evenly;

[0018] Step 4: Vacuum to remove air bubbles;

[0019] Step 5, pouring into a mold and curing to obtain a multi-domain liquid crystal elastomer;

[0020] Step 6: After the multi-domain liquid crystal elastomer is stretched and fixed, it is irradiated with ultraviolet light to obtain a two-component liquid crystal polymer resin material.

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

[0022] (1) The method for preparing a single-domain liquid crystal elastomer using a two-component liquid crystal polymer resin proposed in the present invention has the advantages of being solvent-free, simple to operate, and having a short preparation cycle. In addition, the prepared liquid crystal elastomer has good stability and excellent actuation performance and mechanical properties.

[0023] (2) The present invention can adjust the actuation performance and mechanical properties of the liquid crystal elastomer by simply changing the ratio and dosage of components A and B, and has good adjustability, especially during molding and stretching processing, and has excellent processing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a photo of the AB component of the present invention;

[0025] Figure 2 The stress-strain curves of the liquid crystal elastomers prepared in Examples 1 to 4 of the present invention;

[0026] Figure 3 The actuation strain test diagram of the liquid crystal elastomer prepared in Examples 1 to 4 of the present invention;

[0027] Figure 4 The reversible deformation cycle diagram of the liquid crystal elastomer prepared in Examples 1 to 4 of the present invention. DETAILED DESCRIPTION

[0028] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0029] A specific embodiment of the present invention, as Figure 1-Figure 4 , discloses a two-component liquid crystal polymer resin material, including component A and component B;

[0030] Wherein, component A is a liquid crystal oligomer, which is prepared by reaction of an acrylate liquid crystal monomer, a dithiol chain extender and a catalyst;

[0031] The acrylic ester liquid crystal monomer is a liquid crystal unit terminated with different diacrylates, such as 4-((6-(acryloyloxy)hexyl)oxy)phenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate (C6BAPE), 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (RM257) or 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), preferably RM257.

[0032] The dithiol chain extender is 1,3-propanedithiol, 3,6-dioxa-1,8-octanedithiol (EDDET) or 1,5-pentanedithiol, etc., preferably EDDET.

[0033] Wherein, the catalyst is di-n-propylamine (DPA).

[0034] Component B includes a dithiol chain extender, a cross-linking agent, a catalyst and a photoinitiator;

[0035] Among them, the dithiol chain extender is 3,6-dioxa-1,8-octanedithiol (EDDET); the cross-linking agent is pentaerythritol tetrakis(3-mercaptopropionic acid) ester (PETMP); the catalyst is di-n-propylamine (DPA) and the photoinitiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (I2959).

[0036] In order to illustrate the effectiveness of the two-component liquid crystal polymer resin material proposed in the present invention, the above technical solution is described in detail through experiments below. The specific implementation steps are as follows:

[0037] (1) 7.06 g of liquid crystal element RM257 reacts with 1.09 g of dithiol chain extender EDDET and 0.03 g of catalyst DPA to obtain component A;

[0038] (2) 0.44 g EDDET, 0.51 g PETMP, 0.05 g I2595 and 0.03 g DPA were mixed to obtain component B;

[0039] (2) 8.18 g of component A and 1.03 g of component B were mixed at 80°C;

[0040] (3) Vacuum to remove air bubbles;

[0041] (4) pouring into a mold and curing at 80° C. for 3 h to obtain a multi-domain liquid crystal elastomer;

[0042] (5) The multi-domain liquid crystal elastomer is stretched to λ=2 and fixed, and irradiated with ultraviolet light for 30 min to obtain a mono-domain liquid crystal elastomer.

[0043] Effect: The tensile modulus of the liquid crystal elastomer finally prepared can reach 9MPa, and the actuation strain is 30.0%.

[0044] Another aspect of the present invention discloses a method for preparing a two-component liquid crystal polymer resin material, the specific steps of which are:

[0045] Step 1, dissolving an acrylate liquid crystal monomer in dichloromethane, adding a dithiol chain extender and a catalyst, and stirring the mixture at room temperature to obtain a liquid crystal oligomer solution; removing dichloromethane from the solution by rotary evaporation to obtain component A;

[0046] Furthermore, the acrylate liquid crystal monomer is a different diacrylate-terminated liquid crystal unit such as 4-((6-(acryloyloxy)hexyl)oxy)phenyl 4-((6-(acryloyloxy)hexyl)oxy)benzoate (C6BAPE) or 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (RM257) or 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), preferably RM257.

[0047] Furthermore, the dithiol is 1,3-propanedithiol, 3,6-dioxa-1,8-octanedithiol (EDDET), 1,5-pentanedithiol, etc., preferably EDDET.

[0048] Furthermore, the catalyst is di-n-propylamine.

[0049] Furthermore, the molar ratio of dithiol to acrylate liquid crystal monomer is 1-7:2-8, preferably 1:2.

[0050] Furthermore, the mass of the catalyst accounts for 0.1% to 0.4% of the total mass of the acrylate liquid crystal monomer and the dithiol, and preferably 0.3%.

[0051] Step 2, uniformly mixing the chain extender, the crosslinking agent, the catalyst and the photoinitiator to obtain component B;

[0052] Further, the chain extender is 3,6-dioxa-1,8-octanedithiol (EDDET); the crosslinker is pentaerythritol tetrakis(3-mercaptopropionate) (PETMP); the catalyst is di-n-propylamine (DPA) and the photoinitiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (I2959).

[0053] The structural formulas are:

[0054]

[0055] Furthermore, the molar ratio of the chain extender to the crosslinking agent in component B is 0.5 to 6:1, preferably 4:1.

[0056] Furthermore, the mass of the catalyst in component B accounts for 1% to 3% of the total mass of the chain extender and the cross-linking agent, preferably 2%.

[0057] Furthermore, the mass of the photoinitiator in component B accounts for 4.5% to 9% of the total mass of the chain extender and the crosslinking agent, preferably 4.5%.

[0058] Step 3, mix component A and component B evenly;

[0059] Furthermore, the mass ratio of components A and B is: A:B=6-9:1, preferably 8:1.

[0060] Furthermore, the relationship between the mass ratio of components A and B and the tensile modulus of the liquid crystal elastomer is:

[0061] y=3.3*10 4 -1.3*10 4 x+1.7*10 3 x 2 -7.4*10 1 x 3 .

[0062] Wherein, x is the mass ratio of components A and B, and y is the tensile modulus of the liquid crystal elastomer finally prepared.

[0063] Furthermore, the mixing temperature is 80°C to 100°C, preferably 80°C.

[0064] Step 4: Vacuum to remove air bubbles;

[0065] Step 5, pouring into a mold and curing to obtain a multi-domain liquid crystal elastomer;

[0066] The curing temperature is -80°C to 25°C, preferably 80°C.

[0067] The curing time is 3 hours to 24 hours, preferably 12 hours.

[0068] Step 6: After the multi-domain liquid crystal elastomer is stretched and fixed, it is irradiated with ultraviolet light to obtain a single-domain liquid crystal elastomer (ie, a two-component liquid crystal polymer resin material).

[0069] The stretching ratio is λ=1.8-2.5, preferably λ=2.

[0070] The wavelength of ultraviolet light is 200 to 400 nm, preferably 365 nm.

[0071] The ultraviolet light power is 20-30W, preferably 20W.

[0072] The irradiation distance is 5 cm-20 cm, preferably 15 cm.

[0073] The irradiation time is 20 min-60 min, preferably 30 min.

[0074] In order to illustrate the effectiveness of the method proposed in the present invention, the above technical solution of the present invention is described in detail through four specific embodiments below, and the specific implementation steps are as follows:

[0075] Example 1

[0076] A method for preparing a two-component liquid crystal elastomer comprises the following steps:

[0077] (1) 8.18 g of component A and 1.12 g of component B (EDDET:PETMP=0.57:1) were mixed at 80°C;

[0078] (2) Vacuum to remove air bubbles;

[0079] (3) pouring into a mold and curing at 80° C. for 3 h to obtain a multi-domain liquid crystal elastomer;

[0080] (4) The multi-domain liquid crystal elastomer is stretched to λ=2 and fixed, and irradiated with ultraviolet light for 30 min to obtain a mono-domain liquid crystal elastomer.

[0081] This sample was labeled LCE15.

[0082] Example 2

[0083] A method for preparing a two-component liquid crystal elastomer comprises the following steps:

[0084] (1) 8.18 g of component A and 1.06 g of component B (EDDET:PETMP=1.43:1) were mixed at 80°C;

[0085] (2) Vacuum to remove air bubbles;

[0086] (3) pouring into a mold and curing at 80° C. for 3 h to obtain a multi-domain liquid crystal elastomer;

[0087] (4) The multi-domain liquid crystal elastomer is stretched to λ=2 and fixed, and irradiated with ultraviolet light for 30 min to obtain a mono-domain liquid crystal elastomer.

[0088] This sample is labeled LCE11.

[0089] Example 3

[0090] A method for preparing a two-component liquid crystal elastomer comprises the following steps:

[0091] (1) 8.18 g of component A and 1.03 g of component B (EDDET:PETMP=2.29:1) were mixed at 80°C;

[0092] (2) Vacuum to remove air bubbles;

[0093] (3) pouring into a mold and curing at 80° C. for 3 h to obtain a multi-domain liquid crystal elastomer;

[0094] (4) The multi-domain liquid crystal elastomer is stretched to λ=2 and fixed, and irradiated with ultraviolet light for 30 min to obtain a mono-domain liquid crystal elastomer.

[0095] This sample was labeled LCE9.

[0096] Example 4

[0097] A method for preparing a two-component liquid crystal elastomer comprises the following steps:

[0098] (1) 8.18 g of component A and 1.01 g of component B (EDDET:PETMP=3.14:1) were mixed at 80°C.

[0099] (2) Vacuum to remove air bubbles;

[0100] (3) pouring into a mold and curing at 80° C. for 3 h to obtain a multi-domain liquid crystal elastomer;

[0101] (4) The multi-domain liquid crystal elastomer is stretched to λ=2 and fixed, and irradiated with ultraviolet light for 30 min to obtain a mono-domain liquid crystal elastomer.

[0102] This sample was labeled LCE4.

[0103] Performance Testing

[0104] (1) Mechanical properties test

[0105] The liquid crystal elastomer samples prepared in Examples 1 to 4 were subjected to uniaxial tensile testing on an electronic universal testing machine (WANCE), with a sample size of 30 mm×10 mm×0.5 mm and a tensile rate of 0.2 min. -1 , the results are as follows Figure 2 By simply changing the ratio and amount of component B, the mechanical properties of the liquid crystal elastomer are also well adjustable. In Examples 1 to 4, the tensile strength of the liquid crystal elastomer can reach up to 5.92 MPa, the elongation at break can reach up to 58%, and the modulus can reach up to 15.4 MPa.

[0106] (2) Actuation performance test

[0107] The liquid crystal elastomer samples prepared in Examples 1 to 4 were subjected to an actuation strain test on a hot stage at 120° C. The sample size was 40 mm×10 mm×0.5 mm. The results are as follows: Figure 3 By simply changing the ratio and amount of component B, the actuation performance of the liquid crystal elastomer is also well adjustable. In Examples 1 to 4, the actuation strain of the liquid crystal elastomer can reach up to 32.5%.

[0108] (3) Cyclic performance test

[0109] The liquid crystal elastomer samples prepared in Examples 1 to 4 were subjected to a reversible actuation cycle test on a hot stage at 120°C. The sample size was 40 mm×10 mm×0.5 mm. The number of cycles was 20. The results are as follows: Figure 4 The actuation strain of the liquid crystal elastomer samples prepared in Examples 1 to 4 remained substantially unchanged during 20 heating and cooling cycles, which proves that the liquid crystal elastomer prepared in the present invention has good stability.

[0110] (4) Comparative test between the prior art and the present application

[0111] Chinese patent CN115710354B discloses a method of preparing a liquid crystal elastomer composite film by dissolving a liquid crystal monomer, a crosslinking agent and a chain extender in an organic solvent, mixing them evenly, and then adding an ionic liquid to mix evenly to form a mixed solution, and then initiating a crosslinking reaction. However, the solvent needs to be removed during the film preparation process, and the preparation time is not less than 8 hours. The two-component liquid crystal polymer resin of the present application only takes 3 hours at the shortest to prepare a liquid crystal elastomer, which greatly improves production efficiency.

[0112] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A two-component liquid crystal polymer resin material, characterized in that: It includes component A and component B; Wherein, component A is a liquid crystal oligomer, which is prepared by reaction of a diacrylate-terminated liquid crystal monomer, a dithiol chain extender and a catalyst; Component B includes a dithiol chain extender, a crosslinker, a catalyst and a photoinitiator.

2. The two-component liquid crystal polymer resin material according to claim 1, characterized in that: The acrylic acid ester liquid crystal monomer is 1,4-bis-[4-(3-acryloxypropoxy)benzoyloxy]-2-methylbenzene, 1,4-bis-[4-(6-acryloxyhexyloxy)benzoyloxy]-2-methylbenzene or 4-((6-(acryloxy)hexyl)oxy)phenyl 4-((6-(acryloxy)hexyl)oxy)benzoate.

3. The two-component liquid crystal polymer resin material according to claim 1, characterized in that: The dithiol chain extender is 3,6-dioxa-1,8-octanedithiol or 1,3-propanedithiol or 1,5-pentanedithiol.

4. The two-component liquid crystal polymer resin material according to claim 1, characterized in that: The catalyst is di-n-propylamine.

5. The two-component liquid crystal polymer resin material according to claim 1, characterized in that: The crosslinking agent is pentaerythritol tetrakis(3-mercaptopropionate).

6. The two-component liquid crystal polymer resin material according to claim 1, characterized in that: The photoinitiator was 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone.

7. The two-component liquid crystal polymer resin material according to any one of claims 1 to 6, characterized in that: The molar ratio of the dithiol chain extender to the crosslinking agent in component B is 0.5 to 6:

1.

8. A method for preparing a two-component liquid crystal polymer resin material, used for preparing the two-component liquid crystal polymer resin material according to any one of claims 1 to 7, characterized in that: The specific steps are: Step 1, dissolving a diacrylate-terminated liquid crystal monomer in an organic solvent, adding a dithiol chain extender and a catalyst, and stirring the mixture at room temperature to obtain a liquid crystal oligomer solution; removing the organic solvent from the solution to obtain component A; Step 2, mixing the dithiol chain extender, the cross-linking agent, the catalyst and the photoinitiator to obtain component B; Step 3, mix component A and component B evenly; Step 4: Vacuum to remove air bubbles; Step 5, pouring into a mold and curing to obtain a multi-domain liquid crystal elastomer; Step 6: After the multi-domain liquid crystal elastomer is stretched and fixed, it is irradiated with ultraviolet light to obtain a two-component liquid crystal polymer resin material.

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