Photocuring 3D printing formula of high-strength part containing triphenylene disc-shaped conjugated liquid crystal, high-strength part and preparation method of high-strength part

Abstract

The invention belongs to the technical field of materials, and particularly discloses a photocuring 3D printing formula of a high-strength workpiece containing triphenylene disc-shaped conjugated liquid crystal, the high-strength workpiece and a preparation method of the high-strength workpiece. The printing formula comprises a curing monomer, a cross-linking agent and a photoinitiator; the curing monomer comprises a liquid crystal monomer and a hydrogel monomer, and the cross-linking agent is triphenylene disc-shaped conjugated liquid crystal; the photocuring liquid crystal prepolymer system capable of being used for digital light processing (DLP) 3D printing is prepared according to the formula. DLP 3D printing equipment is used for layer-by-layer curing forming under ultraviolet irradiation, and the subsequent curing treatment and solvent replacement process are combined, so that an intelligent response type printing model with good three-dimensional structure precision, high thermotropic strength performance and a liquid crystal ordered structure is obtained. By regulating and controlling the proportion of the liquid crystal material to the hydrogel material, precise regulation and control of the mechanical strength and the like of a workpiece can be achieved, and the application potential of the disc-shaped liquid crystal material in flexible intelligent devices is expanded.

Description

Technical Field

[0001] The present invention belongs to the field of material technology and relates to the research and development of 3D printing liquid crystal smart materials, and specifically to a light-curing 3D printing formula for a high-strength part containing triphenylene discotic conjugated liquid crystal, a high-strength part, and a preparation method thereof. Background Art

[0002] Triphenylene discotic conjugated liquid crystals are a type of liquid crystal molecular structure composed of multiple rigid aromatic rings symmetrically arranged around a central core. They have a high degree of symmetry and strong π-π stacking ability, and can achieve excellent self-assembly behavior and ordered arrangement characteristics at the molecular level. Due to their discotic conjugated core structure, triphenylene discotic liquid crystals not only have good thermal stability and photoelectric responsiveness, but also exhibit extremely strong anisotropy and long-range order, and can stably form columnar or lamellar liquid crystal phases over a wide temperature range. This highly ordered microstructure can give the material excellent optical, electrical, and mechanical response behaviors, and is particularly suitable for constructing new smart materials with information transmission, high-intensity or directional response functions. In addition, the rich substitution sites in the triphenylene structure provide flexible space for molecular functional modification, making it of important research value and application prospects in the design of high-performance photosensitive liquid crystal monomers.

[0003] Photocuring 3D printing technology, especially digital light processing (DLP) technology, has shown significant advantages in fine structure construction and functional material molding due to its characteristics of fast speed, precision and high spatial resolution. This technology uses a digital micromirror array to control the ultraviolet light irradiation path to achieve layer-by-layer photocrosslinking and curing of photosensitive resins, and can construct components with complex geometry, microscale details and preset functions. DLP technology places higher demands on the structural design of photosensitive materials, requiring the materials to have good photoresponse activity, crosslinking reaction rate and structural stability after curing. Currently, traditional photocurable materials are mostly based on non-ordered resin polymers, which makes it difficult to achieve precision manufacturing with integrated structure and function. The research and development of liquid crystal materials with high self-assembly ability and functional responsiveness and their introduction into the DLP photocuring system has become an important research direction for expanding the performance boundaries of 3D printing materials and realizing the construction of intelligent components. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a light-curing 3D printing formula for high-strength parts containing triphenylene disc-shaped conjugated liquid crystals. The triphenylene disc-shaped conjugated liquid crystals used in the formula have high conjugation and self-assembly properties, and the reactivity and order structure stability of the photosensitive liquid crystal monomers are improved through molecular design; the present invention combines the triphenylene disc-shaped conjugated liquid crystal structure with DLP light-curing 3D printing technology. The organic liquid crystal material can form a highly ordered molecular arrangement in 3D printing, so that the material has anisotropy and programmable deformation ability. Through light-curing technology, the liquid crystal molecular network can achieve reversible deformation under external stimulation, thereby producing a high-strength liquid crystal hydrogel; the present invention realizes the synchronous control of the orderly arrangement of liquid crystal molecules and the precise molding of the three-dimensional structure, significantly improving the structural and functional coupling performance of the light-cured parts, and the obtained parts can be widely used in the fields of flexible electronics and smart materials.

[0005] The present invention is achieved through the following technical solutions:

[0006] A light-curing 3D printing formula for high-strength parts containing triphenylene discotic conjugated liquid crystals is provided, comprising the following components: a curing monomer, a crosslinking agent, and a photoinitiator; the curing monomer comprises a liquid crystal monomer and a hydrogel monomer, and the crosslinking agent is triphenylene discotic conjugated liquid crystals. The structure of the triphenylene discotic conjugated liquid crystals is shown below:

[0007]

[0008] Wherein, X1 to X6 are selected from substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms, X1, X2, X3, X4, X5, and X6 are the same or different, and at least two of X1, X2, X3, X4, X5, and X6 contain a photopolymerizable terminal group, and the photopolymerizable terminal group is one of the following groups:

[0009]

[0010] A further improvement of the present invention is:

[0011] In the curing monomer, the mass ratio or molar ratio of the liquid crystal monomer to the hydrogel monomer is 1:3 to 35;

[0012] The molar ratio of the crosslinking agent to the liquid crystal monomer is 1:10 to 36;

[0013] The mass ratio of the cross-linking agent to the curing monomer is 1:5 to 52;

[0014] The mass ratio of the photoinitiator to the curing monomer is 1:25 to 125.

[0015] Furthermore, the liquid crystal monomer is 6-((4'-cyano-[1,1'-biphenyl]-4-yl)oxy)hexyl acrylate;

[0016] Furthermore, the hydrogel monomer is a mixture of 2-acryloylhydrazide-1-formamide and acrylic acid;

[0017] Furthermore, the photoinitiator is diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide.

[0018] Furthermore, in the hydrogel monomer, the molar ratio of 2-acryloylhydrazide-1-formamide to acrylic acid is 1:1-23.

[0019] A further improvement of the present invention is:

[0020] A method for preparing a high-strength part using the above printing formula comprises the following steps:

[0021] Step (1), mixing the liquid crystal monomer and 2-acryloylhydrazide-1-carboxamide in the hydrogel monomer in an organic solvent and dissolving them completely to form a uniform solution;

[0022] Step (2), adding a photoinitiator to the solution and shaking to dissolve;

[0023] Step (3), adding a crosslinking agent and acrylic acid monomer in the hydrogel monomer, heating and stirring to obtain a transparent printing ink;

[0024] In step (4), the printing ink forms a liquid crystal organic gel product under ultraviolet light irradiation of the DLP 3D printer, and the organic solvent inside the liquid crystal organic gel is replaced with water by a solvent replacement method to obtain a 3D printed high-strength product.

[0025] Furthermore, the organic solvent in step (1) is dimethylformamide or dimethyl sulfoxide or a mixture of the two.

[0026] Furthermore, the heating temperature in step (3) is 50-150°C.

[0027] Furthermore, the wavelength range of the ultraviolet light in step (4) is between 300-450 nm, and the replacement time is 3-15 days.

[0028] A further improvement of the present invention is:

[0029] A high-strength product produced by the above-mentioned production method.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention utilizes a discotic conjugated triphenylene liquid crystal material to form a highly ordered molecular arrangement in 3D printing, endowing the material with anisotropy and programmable deformation capabilities. Through photocuring technology, the liquid crystal molecular network can reversibly deform under external stimulation, resulting in a high-strength liquid crystal hydrogel with broad applications in flexible electronics and smart materials.

[0032] The present invention combines a triphenylene disc-shaped conjugated liquid crystal structure with DLP photocuring 3D printing technology, enabling simultaneous control of the ordered arrangement of liquid crystal molecules and the precise molding of three-dimensional structures, significantly improving the structural-functional coupling performance of photocured parts. Based on the high conjugation and self-assembly properties of triphenylene disc-shaped conjugated liquid crystals, the present invention enhances the reactivity and order structure stability of photosensitive liquid crystal monomers through molecular design, optimizing their photopolymerization reaction rate and molding accuracy during the DLP printing process. During the printing process, the anisotropy and controllable orientation capabilities of the triphenylene disc-shaped conjugated liquid crystal molecules are retained, allowing the final high-strength parts to not only have excellent mechanical response properties, but also achieve reversible deformation and preset shape recovery behavior under specific external stimuli.

[0033] The present invention provides a method for applying triphenylene disc-shaped conjugated liquid crystals to photocuring 3D printing to prepare high-strength parts, breaking through the limitations of traditional photosensitive resins in terms of functionality, structural order and response characteristics. Compared with the existing technology, the preparation process of the present invention introduces triphenylene disc-shaped liquid crystal molecules with high conjugation and self-assembly ability, so that the photosensitive monomers can not only quickly polymerize and cross-link under ultraviolet light irradiation, but also maintain the orderly arrangement of the liquid crystal phase on a microscopic scale, thereby significantly improving the anisotropy, mechanical strength and memory retention ability of the printed structure. By coupling with DLP photocuring technology, the collaborative manufacturing of liquid crystal orientation control and complex three-dimensional structure precision molding is achieved. The high-strength components obtained can quickly respond and restore their original form under external stimuli such as heat and light, showing excellent reversible deformation ability and environmental adaptability. The method of the present invention has the advantages of precise material design, high processing efficiency, strong structural and functional integration, etc. It is suitable for a variety of intelligent manufacturing application scenarios such as flexible electronics, smart medical devices and wearable systems, and has important engineering promotion value and scientific research innovation significance.

[0034] The three-dimensional liquid crystal component constructed by the method of the present invention has structural complexity, response functionality and processing efficiency, providing a new path and key material foundation for the development of multifunctional flexible electronic devices, intelligent driving components and high-performance sensing systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the H NMR spectrum of the triphenylene discotic conjugated liquid crystal used in Example 1;

[0036] Figure 2This is the H NMR spectrum of the triphenylene discotic conjugated liquid crystal used in Example 2;

[0037] Figure 3 These are stress-strain curves of the test specimens printed in Examples 1 and 2 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0038] The present invention will be described in detail below with reference to specific embodiments.

[0039] Example 1

[0040] (1) Preparation of triphenylene discotic conjugated liquid crystal 4a,4b,8a,8b,12a,12b-hexahydrotriphenylene-2,3,6,7,10,11-hexaylhexa(4-((6-(acryloyloxy)hexyl)oxy)benzoate):

[0041]

[0042] Synthesis of intermediate (3)

[0043] Prepare a 50mL single-necked round-bottom flask, dissolve the intermediate 4-(6-hydroxyhexyloxy)benzoic acid (1) (0.5g, 2.0mmol) in 10ml of dichloromethane, then slowly add a solution of acryloyl chloride (0.1g, 1.8mmol) dissolved in 10ml of dichloromethane using an injection syringe, and finally inject triethylamine (0.2g, 2.0mmol). React for 1h in an ice bath, slowly return to room temperature, and continue stirring for 3h. The reaction is confirmed to be complete by plate dot, and the pH value is adjusted to 6-7 with dilute hydrochloric acid. Then, extract with water and dichloromethane three times, and remove water from the organic matter with sodium sulfate. The organic matter is dried by rotary evaporation, and silica gel is added for purification by column chromatography. The elution solvent is petroleum ether and dichloromethane (PE:DCM=5:1-1:1), to obtain a white solid product (intermediate 3) with a yield of 87%.

[0044] Synthesis of Triphenylene Discotic Conjugated Liquid Crystals (5)

[0045] Prepare a 100 mL single-necked round-bottom flask, add the intermediate 2,3,6,7,10,11-hexahydroxytriphenyl (4) (0.2 g, 0.6 mmol), the intermediate 4-(6-(acryloyloxy)hexyloxy)benzoic acid (3) (1.6 g, 5.5 mmol) in 20 ml The reaction mixture was dissolved in DCM, and 4-dimethylaminopyridine (4-DMAP) (11.3 mg, 0.1 mmol), dicyclohexylcarbodiimide (DCC) (0.9 g, 4.4 mmol), and 2,6-di-tert-butyl-p-cresol (0.5 g, 2.2 mmol) were added. The reaction was carried out in a dark environment at 25°C for 72 h. The reaction was completed by plate counting. The salt generated by the reaction was filtered out, and the filtrate was extracted three times with water and dichloromethane. The water in the organic matter was then removed with sodium sulfate. The organic matter was dried on a rotary evaporator and purified by column chromatography with silica gel. The elution solvent was petroleum ether and dichloromethane (PE:Ea=10:1-2:1) to obtain a liquid crystal compound with a reaction yield of 72%.

[0046] 1 H NMR(400MHz,Chloroform-d)δ8.39(s,6H),7.94(d,J=8.6Hz,12H),6.71(d,J=8.5Hz,12H),6.40(dd,J=17.3,1.5Hz,6H),6.11(dd,J=17.3,10.4H z,6H),5.81(dd,J=10.5,1.5Hz,6H),4.17(t,J=6.7Hz,12H),3.93(t,J=6 .4Hz,12H),1.84–1.74(m,12H),1.74–1.67(m,12H),1.55–1.40(m,24H).

[0047] (2) Preparation of 3D printed high-strength parts containing triphenylene discotic conjugated liquid crystals

[0048] 6-((4'-cyano-[1,1'-biphenyl]-4-yl)oxy)hexyl acrylate (1.0 g, 2.8 mmol) and 2-acryloylhydrazide-1-carboxamide (2.0 g, 15.4 mmol) were dissolved in dimethyl sulfoxide and placed on a roller shaker at 80 rpm to completely dissolve;

[0049] Add the photoinitiator diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (0.04 g, 0.1 mmol) to the solution and shake on a roller shaker until TPO is completely dissolved.

[0050] Add the liquid crystal crosslinking agent (5) (0.5 g, 0.2 mmol) prepared in this example and acrylic acid monomer (1.1 g, 15.2 mol), heat and stir at 100° C. to obtain a transparent printing ink;

[0051] The printing ink forms a liquid crystal organogel component under the ultraviolet light (wavelength of 405nm) of the DLP 3D printer. The organic solvent inside the liquid crystal organogel is replaced with water through the solvent replacement method (replacement time is 7 days), thus obtaining a high-strength component.

[0052] Example 2:

[0053] (1) Preparation of triphenylene discotic conjugated liquid crystal 4a,4b,8a,8b,12a,12b-hexahydrotriphenylene-2,3,6,7,10,11-hexaylhexa(4-((5-(acryloyl-12-azanyl)pentyl)oxy)benzoate):

[0054]

[0055] Synthesis of Triphenylene Discotic Conjugated Liquid Crystals (7)

[0056] Prepare a 250 mL single-necked round-bottom flask, add the intermediate 2,3,6,7,10,11-hexahydroxytriphenyl (4) (1.0 g, 3.0 mmol), the intermediate 4-((5-(acryloyl-12-azanyl)pentyl)oxy)benzoic acid (6) (7.5 g, 27.2 mmol) in 40 mL The mixture was dissolved in DCM, and 4-dimethylaminopyridine (4-DMAP) (55.5 mg, 0.4 mmol), dicyclohexylcarbodiimide (DCC) (4.5 g, 21.7 mmol), and 2,6-di-tert-butyl-p-cresol (0.5 g, 2.2 mmol) were added. The reaction was carried out at 25° C. in a dark environment for 72 h. The reaction was completed after the plate was tapped to determine the end of the reaction. The salt generated by the reaction was filtered out, and the filtrate was extracted three times with water and dichloromethane. The water in the organic matter was then removed with sodium sulfate, and the organic matter was dried using a rotary evaporator. Silica gel was added and purified by column chromatography. The elution solvent was petroleum ether and dichloromethane (PE:Ea=5:1-1:1) to obtain a liquid crystal compound with a reaction yield of 70%.

[0057] 1 H NMR(600MHz,Chloroform-d)δ8.08(d,J=8.9Hz,12H),6.96(d,J=8.9Hz,12H),6.40(dd,J=17.3,1.4Hz,6H),6.12(dd,J=17.3,10.4Hz,6H), 5.82(dd,J=10.4,1.5Hz,6H),4.18(t,J=6.6Hz,12H),4.05(t,J=6.4Hz,12H),1.87–1.81(m,12H),1.76–1.69(m,12H),1.57–1.43(m,24H).

[0058] (2) Preparation of 3D printed high-strength parts containing triphenylene discotic conjugated liquid crystals

[0059] The triphenylene discotic conjugated liquid crystal (7) prepared by the above process of this embodiment is used as a crosslinking agent, and the organic solvent is dimethylformamide. Other operations are roughly the same as those in Example 1 and will not be repeated here.

[0060] Comparative Example 1

[0061] In this comparative example, poly(ethylene glycol) diacrylate was used as the cross-linking agent, and other operations were substantially the same as those in Example 1, which will not be described in detail here.

[0062] Example 3: Parts Performance Testing and Comparison

[0063] The parts prepared in Examples 1 and 2 of the present application were tested and compared with the parts prepared in Comparative Example 1. The parts prepared in Examples 1 and 2 and Comparative Example 1 showed obvious differences in mechanical properties (see Figure 1 ), which fully verified the significant role of triphenylene-containing discotic conjugated liquid crystal monomers in improving the performance of printed parts.

[0064] strain / % Stress / MPa Modulus / MPa Example 1 47.99 0.80 2.67 Example 2 41.64 1.18 9.79 Comparative Example 1 31.83 0.24 0.89

[0065] Specifically, the maximum strain of Example 1 is 47.99%, which is a certain improvement over 31.83% of Comparative Example 1, indicating that it has better ductility; its stress reaches 0.80 MPa, which is much higher than 0.24 MPa of Comparative Example 1, indicating that its tensile strength is significantly enhanced; and the modulus reaches 2.67 MPa, which is nearly twice as high as 0.89 MPa of Comparative Example 1, reflecting stronger structural rigidity and mechanical stability. The comprehensive mechanical properties of Example 2 are the best, with a strain of 41.64%, which is slightly lower than that of Example 3, but 10% higher than that of Comparative Example 1, indicating that it still maintains good toughness. The stress and modulus reach 1.18 MPa and 9.79 MPa, respectively, which are the maximum values among the three sets of data, indicating that its structural rigidity and bearing capacity have been effectively enhanced.

[0066] These performance improvements are mainly derived from the special molecular structure of triphenylene disc-shaped conjugated liquid crystal monomers. Triphenylene is a class of highly symmetrical disc-shaped molecules with significant π-π stacking ability and strong intermolecular force. It is easy to form a highly ordered columnar or layered arrangement structure during photopolymerization, thereby building a dense and uniform microstructure in the polymer network, significantly enhancing the overall strength and modulus of the material. In addition, its large-area conjugated structure not only improves the electron density and intermolecular interaction force of the material, but also improves the efficiency of the photosensitive response during the molding process, making polymerization more sufficient and network crosslinking more dense. In the conjugated liquid crystal molecules in Example 2, the original "acryloyloxy" is replaced by "enoyl-12-azoalkyl" structure, the lone pair of electrons on the nitrogen atom enhances the intermolecular force of the conjugated liquid crystal, stabilizes the liquid crystal orientation structure during photopolymerization, and at the same time, the introduction of the azoalkyl chain enhances the hydrogen bonding and polarity force between the molecular chains, making the conjugated liquid crystal more easily form a dense and stable three-dimensional network structure during photopolymerization crosslinking. In contrast, the liquid crystal molecules used in Comparative Example 1 have a simple molecular structure and weak intermolecular interactions, making it difficult to form an ordered arrangement during polymerization, resulting in poor mechanical properties of the resulting molded parts. Consequently, Examples 1 and 2 significantly outperformed Comparative Example 1 in terms of tensile strength and modulus, demonstrating greater structural integrity and load-bearing capacity, fully demonstrating the potential application of triphenylene discotic liquid crystal structures in the development of high-intensity, light-curable 3D printing materials.

[0067] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A light-cured 3D printing formula for high-strength parts containing triphenylene discotic conjugated liquid crystals, characterized in that: The invention is composed of the following components: a curing monomer, a cross-linking agent and a photoinitiator; the curing monomer includes a liquid crystal monomer and a hydrogel monomer, and the cross-linking agent is a triphenylene discotic conjugated liquid crystal. The structure of the triphenylene discotic conjugated liquid crystal is shown in the following formula: Wherein, X1 to X6 are selected from substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms, X1, X2, X3, X4, X5, and X6 are the same or different, and at least two of X1, X2, X3, X4, X5, and X6 contain a photopolymerizable terminal group, and the photopolymerizable terminal group is one of the following groups:

2. A light-curing 3D printing formula for a high-strength component containing triphenylene discotic conjugated liquid crystal according to claim 1, characterized in that: In the curing monomer, the mass ratio or molar ratio of the liquid crystal monomer to the hydrogel monomer is 1:3 to 35; The molar ratio of the crosslinking agent to the liquid crystal monomer is 1:10 to 36; The mass ratio of the cross-linking agent to the curing monomer is 1:5 to 52; The mass ratio of the photoinitiator to the curing monomer is 1:25 to 125.

3. The light-curing 3D printing formula for a high-strength component containing triphenylene discotic conjugated liquid crystal according to claim 1, characterized in that: The liquid crystal monomer is 6-((4'-cyano-[1,1'-biphenyl]-4-yl)oxy)hexyl acrylate; and / or, the hydrogel monomer is a mixture of 2-acryloylhydrazide-1-formamide and acrylic acid; And / or, the photoinitiator is diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide.

4. A light-curing 3D printing formula for a high-strength component containing triphenylene discotic conjugated liquid crystal according to claim 3, characterized in that: In the hydrogel monomer, the molar ratio of 2-acryloylhydrazide-1-formamide to acrylic acid is 1:1-23.

5. A method for preparing a high-strength part using the printing formula according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step (1), mixing the liquid crystal monomer and 2-acryloylhydrazide-1-carboxamide in the hydrogel monomer in an organic solvent and dissolving them completely to form a uniform solution; Step (2), adding a photoinitiator to the solution and shaking it to dissolve; In step (3), a cross-linking agent and acrylic acid monomer in the hydrogel monomer are added, and the mixture is heated and stirred to obtain a transparent printing ink. In step (4), the printing ink is irradiated with ultraviolet light by a DLP 3D printer to form a liquid crystal organic gel product. The organic solvent inside the liquid crystal organic gel is replaced with water by a solvent replacement method, thereby obtaining a 3D printed high-strength product.

6. The method for preparing a high-strength product according to claim 5, characterized in that: The organic solvent in step (1) is dimethylformamide or dimethyl sulfoxide or a mixture of the two.

7. The method for preparing a high-strength product according to claim 5, characterized in that: The heating temperature in step (3) is 50-150°C.

8. The method for preparing a high-strength product according to claim 5, characterized in that: The wavelength range of the ultraviolet light in step (4) is between 300-450 nm, and the replacement time is 3-15 days.

9. A high-strength product produced by the preparation method according to claim 5.

Images