A two-component liquid crystal polymer resin material and its preparation method

Abstract

This invention relates to a two-component liquid crystal polymer resin material and its preparation method, belonging to the field of intelligent polymer materials technology. The liquid crystal polymer resin obtained by this invention features simple preparation steps and rapid reaction. Preparing a liquid crystal elastomer sample only requires mixing and reacting the two components, followed by stretching and light irradiation, without the need to remove the solvent. The entire process can be completed in as little as a few hours, greatly improving production efficiency. The two-component liquid crystal polymer resin material of this invention includes component A and component B; component A is a liquid crystal oligomer, prepared by reacting a diacrylate-terminated liquid crystal monomer, a dithiol chain extender, and a catalyst; component B includes a dithiol chain extender, a crosslinking agent, a catalyst, and a photoinitiator.

Description

Technical Field

[0001] This invention belongs to the field of intelligent polymer materials technology, specifically relating to a two-component liquid crystal polymer resin material and its preparation method. Background Technology

[0002] Smart materials are a class of functional materials that can undergo macroscopic deformation under changing external conditions. They have been widely used in fields such as deformable structures and intelligent robots, including traditional shape memory alloys, shape memory polymers, dielectric elastomers, smart hydrogels, and liquid crystal elastomers. Compared to traditional smart materials, liquid crystal elastomers have advantages such as anisotropic shrinkage, strong deformation capacity, fast response speed, mild stimulation conditions, and good reversible cycling performance. Furthermore, liquid crystal elastomers can achieve different deformation modes through processing methods such as molding, coating, and 3D printing, meeting the diverse needs of the smart field for high-performance smart soft materials, attracting widespread attention, and possessing broad development potential.

[0003] Liquid crystal elastomers are generally prepared through methods such as liquid crystal cell orientation curing, mechanical stretching, electrospinning, and extrusion 3D printing. The most widely used method for preparing liquid crystal elastomer devices is mechanical stretching followed by curing. However, this method requires adding a solvent to the liquid crystal monomer solid powder, heating it to a high temperature to dissolve it, and then reacting it with other components. After the reaction is complete, the solvent needs to be removed by heating in an oven. The reaction steps are cumbersome and time-consuming; preparing a single oriented liquid crystal elastomer sample takes three days. Chinese patent CN115710354B discloses a method of dissolving liquid crystal monomers, crosslinking agents, and chain extenders in an organic solvent, mixing them evenly, adding an ionic liquid, mixing evenly to form a mixture, and then initiating a crosslinking reaction. This method can produce liquid crystal elastomer composite films with excellent mechanical properties. However, the solvent needs to be removed during film preparation, resulting in a long preparation cycle, making it unsuitable for 3D printing. CN114851551B describes a method for preparing liquid crystal elastomer 3D printing ink by mixing and melting liquid crystal macromolecular monomers with photoinitiators, crosslinking agents, thermal initiators, and thiols at room temperature. However, the reaction time is long, requiring 3-48 hours to ensure complete reaction, which affects printing efficiency. CN113977943A discloses a method of selectively curing the molded material by extruding and depositing liquid crystal elastomer material using ultraviolet light sweeping to control the total ultraviolet irradiation dose received by different regions, thereby controlling the crosslinking density of different regions of the material. This method focuses on the subsequent 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 its preparation method. The liquid crystal polymer resin obtained by the present invention has the characteristics of simple preparation steps and rapid reaction. To prepare a liquid crystal elastomer sample, it is only necessary to mix and react the two components, stretch and irradiate them, without removing the solvent. At the same time, the entire process can be completed in as little as a few hours (as short as 3 hours under laboratory conditions), which greatly improves production efficiency.

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

[0006] 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.

[0007] Component B includes dithiol chain extenders, crosslinking agents, catalysts, and photoinitiators.

[0008] Optionally, the acrylate liquid crystal monomer is 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, or 4-((6-(acryloyloxy)hexyl)oxy)phenyl4-((6-(acryloyloxy)hexyl)oxy)benzoate.

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

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

[0011] Optionally, the crosslinking agent is pentaerythritol tetrakis(3-mercaptopropionic acid) ester.

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

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

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

[0015] Step 1: Dissolve the diacrylate-terminated liquid crystal monomer in an organic solvent, add dithiol chain extender and catalyst, and stir the reaction at room temperature to obtain a liquid crystal oligomer solution; remove the organic solvent from the solution to obtain component A;

[0016] Step 2: Mix the dithiol chain extender, crosslinking agent, catalyst and photoinitiator evenly to obtain component B;

[0017] Step 3: Mix component A and component B thoroughly;

[0018] Step 4: Remove air bubbles using vacuum.

[0019] Step 5: Pour into a mold and cure to obtain a multi-domain liquid crystal elastomer;

[0020] Step 6: After stretching and fixing the multi-domain liquid crystal elastomer, irradiate it 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 single-domain liquid crystal elastomers from two-component liquid crystal polymer resins proposed in this invention has the advantages of being solvent-free, simple to operate, and having a short preparation cycle; and the prepared liquid crystal elastomers have good stability and excellent actuation and mechanical properties.

[0023] (2) By simply changing the ratio and amount of components A and B, the present invention can control the actuation and mechanical properties of liquid crystal elastomers, which has good adjustability and excellent processing performance, especially in molding and stretching processes. Attached Figure Description

[0024] Figure 1 Photographs of the AB components of this invention;

[0025] Figure 2 The stress-strain curves of the liquid crystal elastomers prepared in Examples 1-4 of this invention are shown.

[0026] Figure 3 These are the actuation strain test diagrams of the liquid crystal elastomers prepared in Examples 1-4 of this invention;

[0027] Figure 4 The diagram shows the reversible deformation cycle of the liquid crystal elastomers prepared in Examples 1-4 of this invention. Detailed Implementation

[0028] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0029] A specific embodiment of the present invention, such as Figures 1-4 A two-component liquid crystal polymer resin material is disclosed, comprising component A and component B;

[0030] Component A is a liquid crystal oligomer, which is prepared by reacting acrylate liquid crystal monomers, dithiol chain extenders and catalysts.

[0031] 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), 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (RM257) or 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), with RM257 being preferred.

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

[0033] The catalyst is di-n-propylamine (DPA).

[0034] Component B includes dithiol chain extenders, crosslinking agents, catalysts, and photoinitiators;

[0035] The dithiol chain extender is 3,6-dioxa-1,8-octanedithiol (EDDET); the crosslinking 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-methylphenylacetone (I2959).

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

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

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

[0039] (2) Mix 8.18g of component A and 1.03g of component B evenly at 80℃;

[0040] (3) Vacuum removal of air bubbles;

[0041] (4) Pour into a mold and cure at 80°C for 3 hours to obtain a multi-domain liquid crystal elastomer;

[0042] (5) Stretch the multi-domain liquid crystal elastomer to λ=2 and fix it, then irradiate it with ultraviolet light for 30 min to obtain a single-domain liquid crystal elastomer.

[0043] Results: The tensile modulus of the final prepared liquid crystal elastomer can reach 9 MPa, 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 as follows:

[0045] Step 1: Dissolve the acrylate liquid crystal monomer in dichloromethane, add dithiol chain extender and catalyst, and stir the reaction at room temperature to obtain a liquid crystal oligomer solution; remove the 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), 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (RM257), or 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), preferably RM257.

[0047] Further, the dithiol is 1,3-propanedithiol, 3,6-dioxa-1,8-octanedithiol (EDDET), or 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 catalyst accounts for 0.1% to 0.4% of the total mass of the acrylate liquid crystal monomer and dithiol, preferably 0.3%.

[0051] Step 2: Mix the chain extender, crosslinking agent, catalyst and photoinitiator evenly to obtain component B;

[0052] Furthermore, the chain extender is 3,6-dioxa-1,8-octanedithiol (EDDET); the crosslinking 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-methylphenylacetone (I2959).

[0053] Their structural formulas are as follows:

[0054]

[0055] Furthermore, the molar ratio of chain extender to crosslinker 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 crosslinking agent, preferably 2%.

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

[0058] Step 3: Mix component A and component B thoroughly;

[0059] Furthermore, the mass ratio of components A and B is A:B = 6 to 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 as follows:

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

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

[0063] Furthermore, the mixing temperature is 80℃~100℃, preferably 80℃.

[0064] Step 4: Remove air bubbles using vacuum.

[0065] Step 5: Pour into a mold and cure to obtain a multi-domain liquid crystal elastomer;

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

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

[0068] Step 6: After stretching and fixing the multi-domain liquid crystal elastomer, irradiate it with ultraviolet light to obtain a single-domain liquid crystal elastomer (i.e., a two-component liquid crystal polymer resin material).

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

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

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

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

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

[0074] To illustrate the effectiveness of the method proposed in this invention, the following four specific embodiments are provided to describe the above technical solution in detail. The specific implementation steps are as follows:

[0075] Example 1

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

[0077] (1) Mix 8.18g of component A and 1.12g of component B (EDDET:PETMP = 0.57:1) at 80℃ until homogeneous;

[0078] (2) Vacuum removal of air bubbles;

[0079] (3) Pour into a mold and cure at 80°C for 3 hours to obtain a multi-domain liquid crystal elastomer;

[0080] (4) Stretch the multi-domain liquid crystal elastomer to λ=2 and fix it, then irradiate it with ultraviolet light for 30 min to obtain a single-domain liquid crystal elastomer.

[0081] The sample was labeled LCE15.

[0082] Example 2

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

[0084] (1) Mix 8.18g of component A and 1.06g of component B (EDDET:PETMP = 1.43:1) at 80℃ until homogeneous;

[0085] (2) Vacuum removal of air bubbles;

[0086] (3) Pour into a mold and cure at 80°C for 3 hours to obtain a multi-domain liquid crystal elastomer;

[0087] (4) Stretch the multi-domain liquid crystal elastomer to λ=2 and fix it, then irradiate it with ultraviolet light for 30 min to obtain a single-domain liquid crystal elastomer.

[0088] The sample was labeled LCE11.

[0089] Example 3

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

[0091] (1) Mix 8.18g of component A and 1.03g of component B (EDDET:PETMP = 2.29:1) at 80℃ until homogeneous;

[0092] (2) Vacuum removal of air bubbles;

[0093] (3) Pour into a mold and cure at 80°C for 3 hours to obtain a multi-domain liquid crystal elastomer;

[0094] (4) Stretch the multi-domain liquid crystal elastomer to λ=2 and fix it, then irradiate it with ultraviolet light for 30 min to obtain a single-domain liquid crystal elastomer.

[0095] The sample was labeled LCE9.

[0096] Example 4

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

[0098] (1) Mix 8.18g of component A and 1.01g of component B (EDDET:PETMP = 3.14:1) at 80℃ until homogeneous;

[0099] (2) Vacuum removal of air bubbles;

[0100] (3) Pour into a mold and cure at 80°C for 3 hours to obtain a multi-domain liquid crystal elastomer;

[0101] (4) Stretch the multi-domain liquid crystal elastomer to λ=2 and fix it, then irradiate it with ultraviolet light for 30 min to obtain a single-domain liquid crystal elastomer.

[0102] The sample was labeled LCE4.

[0103] Performance testing

[0104] (1) Mechanical property testing

[0105] The liquid crystal elastomer samples prepared in Examples 1-4 were subjected to uniaxial tensile tests on a WANCE electronic universal testing machine. The sample dimensions were 30 mm × 10 mm × 0.5 mm, and the tensile rate was 0.2 min. -1 The result is as follows Figure 2 As shown. By simply changing the ratio and amount of component B, the mechanical properties of the liquid crystal elastomer can be well adjusted. In Examples 1-4, 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 1-4 were subjected to actuated strain tests on a hot stage at 120°C. The sample dimensions were 40mm × 10mm × 0.5mm. The results are as follows: Figure 3 As shown. By simply changing the ratio and amount of component B, the actuation properties of the liquid crystal elastomer also exhibit excellent adjustability. In Examples 1-4, 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 1-4 were subjected to reversible actuation cycle tests on a hot stage at 120°C. The sample size was 40mm × 10mm × 0.5mm, and the number of cycles was 20. The results are as follows. Figure 4 As shown, the liquid crystal elastomer samples prepared in Examples 1-4 exhibited essentially unchanged actuation strain during 20 heating and cooling cycles, demonstrating that the liquid crystal elastomer prepared in this invention possesses good stability.

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

[0111] Chinese patent CN115710354B discloses a method for preparing a liquid crystal elastomer composite film by dissolving liquid crystal monomers, crosslinking agents, and chain extenders in an organic solvent, mixing them evenly, adding an ionic liquid, mixing evenly to form a mixture, and then initiating a crosslinking reaction. However, the solvent needs to be removed during the film preparation process, and the preparation time is no less than 8 hours. In contrast, the two-component liquid crystal polymer resin of this application can prepare liquid crystal elastomers in as little as 3 hours, greatly improving production efficiency.

[0112] 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 changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a two-component liquid crystal polymer resin material, characterized in that, Two-component liquid crystal polymer resin materials include component A and component B; 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. Component B includes dithiol chain extenders, crosslinking agents, catalysts, and photoinitiators; The specific steps of the preparation method are as follows: Step 1: Dissolve the diacrylate-terminated liquid crystal monomer in an organic solvent, add dithiol chain extender and catalyst, and stir the reaction at room temperature to obtain a liquid crystal oligomer solution; remove the organic solvent from the solution to obtain component A; Step 2: Mix the dithiol chain extender, crosslinking agent, catalyst and photoinitiator evenly to obtain component B; Step 3: Mix component A and component B thoroughly; Step 4: Remove air bubbles using vacuum. Step 5: Pour into a mold and cure to obtain a multi-domain liquid crystal elastomer; Step 6: After stretching and fixing the multi-domain liquid crystal elastomer, irradiate it with ultraviolet light to obtain a two-component liquid crystal polymer resin material.

2. The preparation method according to claim 1, characterized in that, The bisacrylate-terminated liquid crystal monomers are 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, or 4-((6-(acryloyloxy)hexyl)oxy)phenyl4-((6-(acryloyloxy)hexyl)oxy)benzoate.

3. The preparation method according to claim 1, characterized in that, The dithiol chain extender is 3,6-dioxa-1,8-octanedithiol, 1,3-propanedithiol, or 1,5-pentanedithiol.

4. The preparation method according to claim 1, characterized in that, The catalyst is di-n-propylamine.

5. The preparation method according to claim 1, characterized in that, The crosslinking agent is pentaerythritol tetrakis(3-mercaptopropionic acid) ester.

6. The preparation method according to claim 1, characterized in that, The photoinitiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylphenylacetone.

7. The preparation method according to any one of claims 1-6, characterized in that, The molar ratio of dithiol chain extender to crosslinking agent in component B is 0.5 to 6:1.

Images