阅读说明：本技术 一种宽温域蓝相液晶材料及其制备方法 (Wide-temperature-range blue-phase liquid crystal material and preparation method thereof ) 是由 杨槐 胡威 王萌 张兰英 钟廷珺 于 2018-06-21 设计创作，主要内容包括：本发明属于液晶材料技术领域。具体涉及一种蓝相液晶材料,包括：组分A、组分B、组分C以及组分D。其中,组分A包括一类含联苯结构的双液晶基元混合液晶材料,材料基本结构为两段棒状液晶片段由中间柔韧的碳链相连。组分B包括一类含三联苯结构的双液晶基元混合液晶材料,材料基本结构为两段棒状液晶片段由中间柔韧的碳链相连。组分C包括一类三联苯结构液晶混合材料,此类液晶材料有高的清亮点和高的折射率各向异性。组分D包括一类液晶用手性掺杂剂。采用本发明的蓝相液晶配方,通过合理地混合不同比例的组分A、B、C、D,可以极大的提高蓝相液晶的热力学稳定性,得到温域超宽的蓝相液晶材料。(The invention belongs to the technical field of liquid crystal materials. In particular to a blue phase liquid crystal material, which comprises: component A, component B, component C and component D. The component A comprises a double liquid crystal elementary mixed liquid crystal material containing a biphenyl structure, and the basic structure of the material is that two rod-shaped liquid crystal segments are connected by a flexible carbon chain in the middle. The component B comprises a double liquid crystal elementary mixed liquid crystal material containing a terphenyl structure, and the basic structure of the material is that two rod-shaped liquid crystal segments are connected by a flexible carbon chain in the middle. The component C comprises a liquid crystal mixed material with a terphenyl structure, and the liquid crystal material has a high clearing point and high refractive index anisotropy. Component D comprises a chiral dopant for liquid crystals. By adopting the blue phase liquid crystal formula, the thermodynamic stability of the blue phase liquid crystal can be greatly improved by reasonably mixing the components A, B, C, D in different proportions, and the blue phase liquid crystal material with ultra-wide temperature range can be obtained.)

1. A blue phase liquid crystal material, comprising: the blue phase liquid crystal composite comprises a component A, a component B, a component C and a component D, wherein the total mass of the component A, the component B and the component C accounts for 50-95% of the total mass of the blue phase liquid crystal, and the total mass of the component D accounts for 5-50% of the total mass of the blue phase liquid crystal;

the component A comprises a double liquid crystal elementary mixed liquid crystal material containing a biphenyl structure, and the basic structure of the material is that two rod-shaped liquid crystal segments are connected by a flexible carbon chain in the middle;

the component B comprises a double liquid crystal elementary mixed liquid crystal material containing a terphenyl structure, and the basic structure of the material is that two rod-shaped liquid crystal segments are connected by a flexible carbon chain in the middle;

the component C comprises a liquid crystal mixed material with a terphenyl structure;

component D comprises a chiral dopant for liquid crystals.

2. The blue phase liquid crystal material according to claim 1, wherein the ratio of the total mass of component A plus component B to the mass of component C is 1: 9-9: 1.

3. the blue phase liquid crystal material according to claim 2, wherein the mass ratio of the component A to the component B is 1: 9-9: 1.

4. the blue phase liquid crystal material according to claim 1, wherein component A is a mixture of one or more compounds represented by the following general formula in any ratio:

wherein n is 3, 5, 7, 9, 11, 13, R is F, CN or C_mH_2m+1And m is an integer of 1 to 9.

5. The blue phase liquid crystal material according to claim 1, wherein component B is a mixture of one or more compounds represented by the following general formula in any ratio:

wherein n is 3, 5, 7, 9, 11, 13, R is F, CN or C_mH_2m+1And m is an integer of 1 to 9.

6. The blue phase liquid crystal material according to claim 1, wherein component C is a mixture of one or more compounds represented by the following general formula in any ratio:

wherein, R group is F, CN or C_mH_2m+1And m is an integer of 1 to 9.

7. The blue phase liquid crystal material according to claim 1, wherein component D is a mixture of one or more compounds represented by the following general formula in any ratio:

8. a method of preparing a blue phase liquid crystalline material according to any one of claims 1 to 7, the method comprising the steps of:

1) respectively heating the component A and the component B until the components A and B are clear, and then uniformly mixing the component A and the component B;

2) mixing the component C with the mixture obtained in the step 1), and heating until the mixture is clear to obtain a mixture;

3) adding component D to the mixture obtained in step 2); mixing them uniformly, heating to clear and obtain uniform mixture;

4) filling the mixture obtained in the step 3) into a liquid crystal box, placing the liquid crystal box on a hot table, observing the liquid crystal phase state along with the temperature by using a polarizing microscope, and recording the change temperature of the liquid crystal phase state.

Technical Field

The invention belongs to the field of liquid crystal materials, and particularly relates to a wide-temperature-range blue-phase liquid crystal material and a preparation method thereof.

Background

Blue phase liquid crystal (BP) is a double-helical three-dimensional superstructure material, usually present in high chiral systems. The liquid crystal molecules are self-assembled to form a double-twisted cylinder with a double-helix structure under the twisting force provided by the chiral agent. According to different arrangement modes of the double-twisted cylinders, the blue phase can be roughly divided into three sub-phase states, namely body-centered cubic BP I, simple cubic BP II and irregular atomized phase BP III. Due to the complex three-dimensional structure of the blue phase, liquid crystal molecules have no average director on a macroscopic scale, and therefore, the blue phase liquid crystal has the characteristic of optical isotropy. However, the helical structure of the blue phase liquid crystal forms a periodic distribution of refractive index, resulting in bragg reflection. The Bragg reflection wavelengths of different crystal planes are different, so that a blue phase observed under a polarization microscope presents a color fragment structure.

Blue phase liquid crystals have many excellent optical characteristics, and have attracted more and more attention because of a series of special optical characteristics, such as the ability to selectively reflect visible light and the absence of birefringence, which is common in optics. The blue phase is a stable phase that often occurs in a very small temperature range near the clearing point of high chiral liquid crystal systems. In order to obtain the wide-temperature-range blue-phase liquid crystal, so that the blue-phase liquid crystal can be widely applied, the existing wide-temperature-range blue-phase liquid crystal technology can be mainly divided into two types. The first technique is to stabilize the defects of the blue phase liquid crystal to thereby stabilize the blue phase liquid crystal. For example, the documents Kikuchi H, Yokota M, Hisakado Y, Yang H, Kajiyama T,2002, nat. Mater.1,64 disclose a method for stabilizing the blue phase using a polymer, which yields a blue phase liquid crystal having a blue phase temperature width of up to 60 ℃ at room temperature. The second technology is to synthesize blue phase liquid crystal with wide temperature range through molecular design. For example, the reference Coles HJ, PivneckoMN, Nature,436(18),997, designs and synthesizes fluorine-containing substituted dimer liquid crystal molecules, and has a wide blue phase temperature range of 44 ℃ inclusive of room temperature. Although the existing blue phase liquid crystal technology with wide temperature range solves the problem of wide and narrow blue phase temperature range of the blue phase liquid crystal to a certain extent, the blue phase temperature range of the existing blue phase liquid crystal system is widened and limited, and the blue phase temperature range can be adjusted only within the range of +/-30 ℃ of standard room temperature (25 ℃). That is, the existing blue phase liquid crystal cannot meet the application requirements in high environmental temperature areas and extreme low temperature environmental temperatures (such as high outdoor temperature areas in africa, high altitude environments and ultra-low temperature environments in high altitude areas such as north and south), so the application of the blue phase liquid crystal in extreme environmental temperature conditions is limited. Further intensive studies are required to further broaden the temperature range of the blue phase liquid crystal to a large extent.

Disclosure of Invention

The invention aims to provide a blue phase liquid crystal material which has an ultra-wide blue phase temperature range and completely covers the environmental temperature under extreme conditions.

Another object of the present invention is to provide a method for manufacturing a blue phase liquid crystal material with a wide temperature range, which is simple and has a significant effect.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a blue phase liquid crystal material, which comprises the following components in percentage by mass: the blue phase liquid crystal composite comprises a component A, a component B, a component C and a component D, wherein the total mass of the component A, the component B and the component C accounts for 50-95% of the total mass of the blue phase liquid crystal, and the total mass of the component D accounts for 5-50% of the total mass of the blue phase liquid crystal;

the component A comprises a double liquid crystal elementary mixed liquid crystal material containing a biphenyl structure, and the basic structure of the material is that two rod-shaped liquid crystal segments are connected by a flexible carbon chain in the middle;

the component B comprises a double liquid crystal elementary mixed liquid crystal material containing a terphenyl structure, and the basic structure of the material is that two rod-shaped liquid crystal segments are connected by a flexible carbon chain in the middle;

the component C comprises a liquid crystal mixed material with a terphenyl structure; such liquid crystal materials have a high clearing point and a high refractive index anisotropy.

Component D comprises a chiral dopant for liquid crystals.

Preferably, the mass ratio of the total mass of the component A and the component B to the mass of the component C is 1: 9-9: 1.

preferably, the mass ratio of the component A to the component B is 1: 9-9: 1.

preferably, the component A is prepared by mixing any one or more compounds shown in the following general formula in any proportion:

wherein n is 3, 5, 7, 9, 11, 13, R is F, CN or C_mH_2m+1And m is an integer of 1 to 9.

Preferably, the component B is prepared by mixing any one or more compounds shown in the following general formula in any proportion:

wherein n is 3, 5, 7, 9, 11, 13, R is F, CN or C_mH_2m+1And m is an integer of 1 to 9.

Preferably, the component C is prepared by mixing any one or more compounds shown in the following general formula in any proportion:

wherein, R group is F, CN or C_mH_2m+1And m is an integer of 1 to 9.

Preferably, the structures listed above are representative structural formulas and other similar structures derived from this invention are also within this invention.

Preferably, component D is prepared by mixing any one or more compounds shown in the following general formula in any proportion: preference for use with

Preferably, component D is not limited to these classes of chiral agents, and the use of other chiral agents is also within the scope of the invention.

The invention also provides a preparation method of the blue phase liquid crystal material, which comprises the following steps:

1) respectively heating the component A and the component B until the components A and B are clear, and then uniformly mixing the component A and the component B;

2) mixing the component C with the mixture obtained in the step 1), and heating until the mixture is clear to obtain a uniform mixture;

3) adding component D to the mixture obtained in step 2); mixing them, heating to clear and obtain uniform mixture;

4) filling the mixture obtained in the step 3) into a liquid crystal box, placing the liquid crystal box on a hot table, observing the liquid crystal phase state along with the temperature by using a polarizing microscope, and recording the change temperature of the liquid crystal phase state.

Preferably, when component A, component B or component C is a mixture, the mixture in each component is heated separately and then mixed, and then the mixed component (A, B or C) is mixed with the other components.

Compared with the prior art, the invention has the advantages that:

the blue phase parent liquid crystal obtained by the method provided by the invention before adding the chiral agent (component D) has a super-wide liquid crystal temperature range, so that the system has low requirements on the chiral agent, and a large number of chiral agents can be selected. The widest blue phase temperature range of the existing micromolecule blue phase system is less than 50 ℃, the blue phase temperature range of the polymer stabilizing system is not about 60 ℃, and the practical requirements of the blue phase liquid crystal material are difficult to completely meet.

The blue phase liquid crystal material with ultra-wide temperature range can be obtained by reasonably mixing the four components mentioned in the invention, the temperature of the thermodynamically stable blue phase can be adjusted between-195 ℃ and 100 ℃, and the widest temperature range of the stably existing blue phase can exceed 280 ℃. The blue phase liquid crystal material has wide temperature range, flexibility and adjustability and simple preparation method.

Detailed Description

The present invention will be further described with reference to the following specific examples.

According to the formula of the blue phase liquid crystal material, uniformly mixing all components in the formula to prepare a mixture;

1) in the formula of the liquid crystal material, a component A and a component B are respectively heated to be clear and then are uniformly mixed, wherein the mass ratio of the component A to the component B is 1: 9-9: 1;

2) in the formula of the liquid crystal material, heating a component C to be clear to obtain a uniform mixture, and then mixing a mixture of a component A and a component B with the component C, wherein the mass ratio of the total mass of the component A and the component B to the component C is 1: 9-9: 1.

3) in the formula of the liquid crystal material, the component A, the component B and the component C are mixed according to a certain proportion, and a certain amount of the component D is added into the mixture, wherein the mass of the component D accounts for 5-50% of the total mass of the blue phase liquid crystal. Wherein, the component D can use one chiral agent alone or a plurality of chiral agents in a mixed way.

4) Heating the materials to be clear, mixing uniformly, pouring the materials into a liquid crystal box, placing the liquid crystal box on a hot table, observing the liquid crystal phase on the hot table by using a polarizing microscope, observing the change of the liquid crystal phase along with the temperature, and recording the change temperature of the liquid crystal phase. According to different use requirements, the sample proportion with parameters suitable for application requirements is selected.