CN118290712B - Liquid crystal polymer with low mechanical anisotropy and preparation method and application thereof - Google Patents
Liquid crystal polymer with low mechanical anisotropy and preparation method and application thereof Download PDFInfo
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- 229920000106 Liquid crystal polymer Polymers 0.000 title claims abstract description 97
- 239000004977 Liquid-crystal polymers (LCPs) Substances 0.000 title claims abstract description 85
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000004973 liquid crystal related substance Substances 0.000 claims abstract description 11
- 238000001125 extrusion Methods 0.000 claims abstract description 7
- 239000000126 substance Substances 0.000 claims abstract description 5
- 239000000178 monomer Substances 0.000 claims description 40
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 claims description 33
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 14
- 238000006243 chemical reaction Methods 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 8
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 7
- 238000006640 acetylation reaction Methods 0.000 claims description 6
- 239000000835 fiber Substances 0.000 claims description 6
- 150000003384 small molecules Chemical class 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 5
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 4
- 238000004891 communication Methods 0.000 claims description 3
- 230000009477 glass transition Effects 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 239000013307 optical fiber Substances 0.000 claims description 3
- 239000002861 polymer material Substances 0.000 claims description 3
- QKIUAMUSENSFQQ-UHFFFAOYSA-N dimethylazanide Chemical group C[N-]C QKIUAMUSENSFQQ-UHFFFAOYSA-N 0.000 claims description 2
- 238000005086 pumping Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 17
- 230000003098 cholesteric effect Effects 0.000 abstract description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 30
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 15
- 238000000034 method Methods 0.000 description 15
- 229910052757 nitrogen Inorganic materials 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 11
- 238000006116 polymerization reaction Methods 0.000 description 10
- GHMLBKRAJCXXBS-UHFFFAOYSA-N resorcinol Chemical compound OC1=CC=CC(O)=C1 GHMLBKRAJCXXBS-UHFFFAOYSA-N 0.000 description 10
- 239000004986 Cholesteric liquid crystals (ChLC) Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- NEQFBGHQPUXOFH-UHFFFAOYSA-N 4-(4-carboxyphenyl)benzoic acid Chemical group C1=CC(C(=O)O)=CC=C1C1=CC=C(C(O)=O)C=C1 NEQFBGHQPUXOFH-UHFFFAOYSA-N 0.000 description 5
- KLDXJTOLSGUMSJ-JGWLITMVSA-N Isosorbide Chemical compound O[C@@H]1CO[C@@H]2[C@@H](O)CO[C@@H]21 KLDXJTOLSGUMSJ-JGWLITMVSA-N 0.000 description 5
- 239000004988 Nematic liquid crystal Substances 0.000 description 5
- 239000006227 byproduct Substances 0.000 description 5
- 239000007795 chemical reaction product Substances 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 229960002479 isosorbide Drugs 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 4
- 125000000304 alkynyl group Chemical group 0.000 description 3
- 125000003118 aryl group Chemical group 0.000 description 3
- 125000000596 cyclohexenyl group Chemical group C1(=CCCCC1)* 0.000 description 3
- 239000013078 crystal Substances 0.000 description 2
- 229920006351 engineering plastic Polymers 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229920006254 polymer film Polymers 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- FBPFZTCFMRRESA-KVTDHHQDSA-N D-Mannitol Chemical class OC[C@@H](O)[C@@H](O)[C@H](O)[C@H](O)CO FBPFZTCFMRRESA-KVTDHHQDSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 125000000113 cyclohexyl group Chemical group [H]C1([H])C([H])([H])C([H])([H])C([H])(*)C([H])([H])C1([H])[H] 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
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- Polyesters Or Polycarbonates (AREA)
Abstract
The application belongs to the technical field of liquid crystal polymers, and discloses a liquid crystal polymer with low mechanical anisotropy, and a preparation method and application thereof. The repeating unit of the liquid crystal polymer has a chemical structure shown in the following formula, wherein X is a rod-shaped structure consisting of rigid groups; y is a non-liquid crystal structure consisting of a flexible chain, a heterogeneous rigid group or a kinking group; z is a chiral group; a. b and c are the molar ratios X, Y and Z respectively, a, b and c are each independently selected from any ratio between 0.1% and 90%, and the sum of a, b and c is 100%. The application combines chiral groups with liquid crystal polymers to prepare novel liquid crystal polymers with cholesteric phase molecule spiral arrangement structures, wherein isotropically arranged liquid crystal molecules realize low mechanical anisotropy of the liquid crystal polymers. After extrusion molding, the material can form preferred orientation of molecules, maintain a certain degree of molecular spiral arrangement and realize low mechanical anisotropy of the material.
Description
Technical Field
The application belongs to the technical field of liquid crystal polymers, and particularly relates to a liquid crystal polymer with low mechanical anisotropy, and a preparation method and application thereof.
Background
The liquid crystal polymer is a polymer material having both liquid crystal properties. Currently, commercial liquid crystal polymers are mainly formed by connecting aromatic rings through ester bonds and connecting the aromatic rings through rigid rod-shaped molecular units. When the liquid crystal is cooled from a liquid crystal state to a solid state, the highly oriented arrangement of molecular chains is kept, the expansion coefficient of the liquid crystal is similar to that of a metal material, and even negative values can occur, so that the liquid crystal polymer product hardly has the problem of shrinkage in the forming process, and the liquid crystal polymer product has high dimensional stability and far more high temperature resistance than that of general engineering plastics, and is known as super engineering plastics. In addition, a large number of aromatic ring structures in the main chain structure of the liquid crystal polymer also endows the liquid crystal polymer with excellent mechanical properties, excellent chemical resistance and excellent electrical stability, so that the liquid crystal polymer has wide application in the industries of aerospace, electronic appliances, national defense and military industry and the like.
In the extrusion molding process of the liquid crystal polymer, the highly regular arrangement of the molecules can be realized by only a small amount of shearing stress. Therefore, the liquid crystal polymer has very high mechanical strength in the molecular long axis direction, but has poor mechanical property and high brittleness in the direction perpendicular to the long axis direction, and is extremely easy to break; the high mechanical anisotropy severely limits the application of the liquid crystal polymer material.
It is highly desirable to synthesize liquid crystal polymers having low mechanical anisotropy.
Disclosure of Invention
The application provides a liquid crystal polymer with low mechanical anisotropy, a preparation method and application thereof, and solves the problems of poor mechanical property, high brittleness and extremely easy fracture caused by high mechanical anisotropy of the existing liquid crystal polymer.
In order to achieve the above purpose, the present application is realized by the following technical scheme.
In a first aspect of the present application, there is provided a liquid crystal polymer having low mechanical anisotropy, wherein the repeating unit has a chemical structure represented by the following formula:
Wherein X is a rod-shaped structure formed by rigid groups;
y is a non-liquid crystal structure consisting of a flexible chain, a heterogeneous rigid group or a kinking group;
Z is a chiral group;
a. b and c are the molar ratios X, Y and Z respectively, a, b and c are each independently selected from any ratio between 0.1% and 90%, and the sum of a, b and c is 100%.
In some embodiments, X is selected from structures represented by formulas (1) - (10):
。
In some embodiments, Y is selected from structures represented by formulas (11) - (16):
wherein m and n are integers, m is more than or equal to 0, and n is more than or equal to 0.
In some embodiments, Z is selected from structures represented by formulas (17) - (19):
。
In some embodiments of the present invention, in some embodiments,
The structural formula of X is as follows:
The structural formula of Y is as follows:
the structural formula of Z is:
c is selected from 1.37% -5.26%.
In some embodiments, the low mechanical anisotropy liquid crystalline polymer has a molecular weight > 5000 and a glass transition temperature above room temperature.
In a second aspect of the present application, there is provided a method for preparing the liquid crystal polymer having low mechanical anisotropy, comprising:
Dissolving a monomer II, a monomer III and acetic anhydride in a solvent for acetylation reaction; then adding a first monomer, and reacting at 110-130 ℃; vacuum pumping is carried out after the reaction to remove small molecules, thus obtaining the liquid crystal polymer with low mechanical anisotropy;
Or:
Mixing the second monomer and the third monomer with acetic anhydride, and performing an acetylation reaction at 140-150 ℃; then adding a first monomer, heating the reaction solution to 310-330 ℃, and vacuumizing to remove small molecules after the reaction to obtain a liquid crystal polymer with low mechanical anisotropy;
Wherein the structural general formula of the monomer I is HOOC-X-COOH;
The general formula of the monomer II is HO-Y-OH;
the structural general formula of the monomer III is HO-Z-OH.
In some embodiments, the solvent is N, N-dimethylamide or pyridine.
In a third aspect of the present application, there is provided an isotropic liquid crystal polymer material in the form of a fiber or a film, which is produced from the liquid crystal polymer having low mechanical anisotropy by extrusion molding.
In a fourth aspect of the present application, there is provided an application of the isotropic liquid crystal polymer material in a 5G antenna, a high frequency communication device, an electronic device or an optical fiber cladding.
In a third aspect of the present application, there is provided the use of the liquid crystal polymer having low mechanical anisotropy in liquid crystal polymer fibers and/or liquid crystal polymer films.
Compared with the prior art, the application has the beneficial effects that:
The application creatively combines chiral groups with liquid crystal polymers to prepare novel liquid crystal polymers with cholesteric phase molecule spiral arrangement structures, wherein isotropically arranged liquid crystal molecules realize low mechanical anisotropy of the liquid crystal polymers.
The liquid crystal polymer material with low mechanical anisotropy can form the preferred orientation of molecules after extrusion molding, and can maintain the molecular helical arrangement to a certain extent, thereby realizing the low mechanical anisotropy of the material on the premise of ensuring the high strength and regular molecular orientation of the material.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art.
FIG. 1 is a texture diagram of a cholesteric chiral liquid crystal polymer prepared in example 1 under a polarizing microscope;
FIG. 2 is a texture diagram of a nematic achiral liquid crystal polymer prepared in comparative example 1 under a polarizing microscope;
FIG. 3 is a schematic diagram showing the arrangement of polymer networks and liquid crystal molecules after stretching of cholesteric liquid crystal polymers and nematic liquid crystal polymers;
FIG. 4 is a graph showing the biaxial mechanical strength test of liquid crystal polymers with different chiral molecule contents.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It will be apparent that the described embodiments are some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the following description of the present embodiment, the terms "include," "comprise," "have," "contain," and the like are open-ended terms, meaning including, but not limited to.
In the following description of the present embodiment, the term "and/or" is used to describe an association relationship of association objects, which means that three relationships may exist, for example, a and/or B may mean: a alone, B alone and both a and B. Wherein A, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship.
In the following description of the present embodiments, the term "at least one" means one or more, and "a plurality" means two or more. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c" may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be understood by those skilled in the art that, in the following description of the present embodiment, the sequence number does not mean that the execution sequence is sequential, and some or all of the steps may be executed in parallel or sequentially, and the execution sequence of each process should be determined by its functions and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.
It will be understood by those skilled in the art that the numerical ranges in the embodiments of the present application are to be understood as specifically disclosing each intermediate value between the upper and lower limits of the ranges. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the application. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless otherwise defined, technical/scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
In a first aspect, the present application provides a liquid crystal polymer having low mechanical anisotropy, wherein the repeating unit has a chemical structure represented by the following formula:
Wherein X is a rod-shaped structure formed by rigid groups;
y is a non-liquid crystal structure consisting of a flexible chain, a heterogeneous rigid group or a kinking group;
Z is a chiral group;
a. b and c are the molar ratios X, Y and Z respectively, a, b and c are each independently selected from any ratio between 0.1% and 90%, and the sum of a, b and c is 100%. Preferably c is selected from 1.37% to 5.26%.
In the present application, X comprises a group which cannot rotate freely in the molecular structure, or is rotation-limited, such as phenyl, cyclohexenyl or alkynyl. In the present application, X preferably comprises phenyl, cyclohexyl, phenyl and cyclohexenyl, phenyl and alkynyl or cyclohexenyl and alkynyl.
In the present application, X is particularly preferably a structure represented by the formulas (1) to (10):
In the present application, Y is a non-liquid crystalline structure composed of a flexible chain, a heterogeneous rigid group or a kinking group, and preferably Y is a structure represented by formulae (11) to (16):
wherein m and n are integers, m is more than or equal to 0, and n is more than or equal to 0.
In the application, Z is a chiral group, and Z is selected from structures shown in formulas (17) - (19):
In the present application, the liquid crystal polymer with low mechanical anisotropy is preferably
The structural formula of X is as follows:
The structural formula of Y is as follows:
the structural formula of Z is:
c is selected from 1.37% -5.26%; the structural formula is as follows:
wherein c is selected from 1.37% -5.26%, and the sum of a, b and c is 100%.
In the present application, it is preferable that the molecular weight of the liquid crystal polymer having low mechanical anisotropy is > 5000, and the glass transition temperature thereof is higher than room temperature.
The liquid crystal polymer with low mechanical anisotropy has a chiral nematic temperature range, and in the temperature range, the liquid crystal polymer presents a spiral molecular arrangement and has a cholesteric liquid crystal molecular spiral structure. Due to the molecular arrangement of each homoproperty, the liquid crystal polymer material with low mechanical anisotropy can form the preferred orientation of molecules and can maintain the molecular spiral arrangement to a certain extent after extrusion molding, so that the low mechanical anisotropy of the material is realized on the premise of ensuring the high strength and regular molecular orientation of the material.
In a second aspect, the present application provides a method for preparing the liquid crystal polymer having low mechanical anisotropy. The preparation method comprises a solution method and a melting method, wherein the solution method comprises the following steps:
dissolving a monomer II, a monomer III and acetic anhydride in a solvent for acetylation reaction; then adding a first monomer, and reacting at 110-130 ℃; and (3) vacuumizing to remove small molecules after the reaction to obtain the liquid crystal polymer with low mechanical anisotropy.
Wherein the structural general formula of the monomer I is HOOC-X-COOH; the general formula of the monomer II is HO-Y-OH; the structural general formula of the monomer III is HO-Z-OH.
The melting method comprises the following steps:
Mixing the second monomer and the third monomer with acetic anhydride, and performing an acetylation reaction at 140-150 ℃; then adding a first monomer, heating the reaction solution to 310-330 ℃, and vacuumizing to remove small molecules after the reaction to obtain a liquid crystal polymer with low mechanical anisotropy;
Wherein the structural general formula of the monomer I is HOOC-X-COOH; the general formula of the monomer II is HO-Y-OH; the structural general formula of the monomer III is HO-Z-OH.
The preparation method of the application has the following synthetic reaction formula:
The preparation method disclosed by the application is simple in process, and the prepared liquid crystal polymer is easy to mold and process and has low mechanical anisotropy.
The liquid crystal polymer with low mechanical anisotropy can be used for preparing liquid crystal polymer fibers with mechanical isotropy or liquid crystal polymer films with mechanical isotropy through extrusion molding. In the liquid crystal polymer fiber or the crystal polymer film, molecules are orderly oriented, high strength and regular arrangement of the molecules can be maintained, and the liquid crystal polymer fiber or the crystal polymer film can be used in the fields of 5G antennas, high-frequency communication devices, electronic devices, optical fiber wrapping layers and the like.
The application is further illustrated by the following examples.
Example 1
In this example, a liquid crystal polymer having low mechanical anisotropy is provided, in which X is a structure represented by formula (1), Y is a structure represented by formula (12), Z is a structure represented by formula (17), a=51.67%, b=46.97%, and c=1.37%.
The preparation method comprises the following steps:
1. 0.1 mol resorcinol, 0.0029 mol isosorbide and 0.15mol acetic anhydride were dissolved in 200 ml pyridine, the solution was injected into a 500 ml flask, and 100 min was reacted to fully acetylate the monomers;
2. Introducing nitrogen into a flask for protection, adding 0.11mol of 4, 4' -dicarboxyl biphenyl into the flask, gradually heating to 120 ℃, reacting for 10 hours for polymerization, collecting acetic acid generated in the polymerization process, and gradually stopping nitrogen protection;
3. Vacuumizing and stirring the reacted flask for 30 minutes to remove unreacted micromolecule monomers and micromolecule byproducts;
4. and placing the reaction product under the protection of nitrogen for 12 h, and then cooling to room temperature to obtain the liquid crystal polymer with low mechanical anisotropy.
Example 2
In this example, a liquid crystal polymer having low mechanical anisotropy is provided, in which X is a structure represented by formula (1), Y is a structure represented by formula (12), Z is a structure represented by formula (17), a= 50.97%, b=46.33%, and c=2.7%.
The preparation method comprises the following steps:
1. 0.1 mol resorcinol, 0.0058 mol isosorbide and 0.15mol acetic anhydride were dissolved in 200 ml pyridine, the solution was injected into a 500 ml flask, reacted 100 min to fully acetylate the monomers;
2. introducing nitrogen into a flask for protection, adding 0.11 mol of 4, 4' -dicarboxyl biphenyl into the flask, gradually heating to 120 ℃, reacting for 10 hours for polymerization, collecting acetic acid generated in the polymerization process, and gradually stopping nitrogen protection;
3. Vacuumizing and stirring the reacted flask for 30 minutes to remove unreacted micromolecule monomers and micromolecule byproducts;
4. and placing the reaction product under the protection of nitrogen for 12 h, and then cooling to room temperature to obtain the liquid crystal polymer with low mechanical anisotropy.
Example 3
In this example, a liquid crystal polymer having low mechanical anisotropy is provided, in which X is a structure represented by formula (1), Y is a structure represented by formula (12), Z is a structure represented by formula (17), a=50.3%, b=45.7%, and c=4%.
The preparation method comprises the following steps:
1. 0.1 mol resorcinol, 0.0087 mol isosorbide and 0.15 mol acetic anhydride are dissolved in 200 ml pyridine, the solution is injected into a 500 ml flask, and 100 min is reacted to fully acetylate the monomers;
2. introducing nitrogen into a flask for protection, adding 0.11 mol of 4, 4' -dicarboxyl biphenyl into the flask, gradually heating to 120 ℃, reacting for 10 hours for polymerization, collecting acetic acid generated in the polymerization process, and gradually stopping nitrogen protection;
3. Vacuumizing and stirring the reacted flask for 30 minutes to remove unreacted micromolecule monomers and micromolecule byproducts;
4. and placing the reaction product under the protection of nitrogen for 12 h, and then cooling to room temperature to obtain the liquid crystal polymer with low mechanical anisotropy.
Example 4
In this example, a liquid crystal polymer having low mechanical anisotropy is provided, in which X is a structure represented by formula (1), Y is a structure represented by formula (12), Z is a structure represented by formula (17), a= 49.63%, b=45.11%, and c=5.26%.
The preparation method comprises the following steps:
1. Resorcinol of 0.1 mol, isosorbide of 0.01165 mol and acetic anhydride of 0.15 mol are dissolved in 200 ml pyridine, the solution is injected into a 500 ml flask, and 100 min is reacted to fully acetylate the monomers;
2. introducing nitrogen into a flask for protection, adding 0.11 mol of 4, 4' -dicarboxyl biphenyl into the flask, gradually heating to 120 ℃, reacting for 10 hours for polymerization, collecting acetic acid generated in the polymerization process, and gradually stopping nitrogen protection;
3. Vacuumizing and stirring the reacted flask for 30 minutes to remove unreacted micromolecule monomers and micromolecule byproducts;
4. and placing the reaction product under the protection of nitrogen for 12 h, and then cooling to room temperature to obtain the liquid crystal polymer with low mechanical anisotropy.
Comparative example
The comparative example provides a nematic achiral liquid crystal polymer, X is a structure shown in formula (1), Y is a structure shown in formula (12), and Z is a structure shown in formula (17).
In the comparative example, a chiral molecule providing a Z structure was replaced with a half chiral molecule and a half racemic chiral molecule to obtain a nematic achiral liquid crystal polymer, in which the structure was a=51.67%, b=46.97%, c=0. The preparation method comprises the following steps:
1. 0.1 mol resorcinol, 0.005 mol isosorbide, 0.005 mol dehydrated mannitol and 0.15 mol acetic anhydride are dissolved in 200 ml pyridine, the solution is injected into a 500 ml flask, and 100 min is reacted to fully acetylate the monomers;
2. introducing nitrogen into a flask for protection, adding 0.11 mol of 4, 4' -dicarboxyl biphenyl into the flask, gradually heating to 120 ℃, reacting for 10 hours for polymerization, collecting acetic acid generated in the polymerization process, and gradually stopping nitrogen protection;
3. Vacuumizing and stirring the reacted flask for 30 minutes to remove unreacted micromolecule monomers and micromolecule byproducts;
4. and placing the reaction product under the protection of nitrogen for 12 h, and then cooling to room temperature to obtain the liquid crystal polymer with low mechanical anisotropy.
The texture of the liquid crystal polymer prepared in example 1 was observed by a polarizing microscope, as shown in FIG. 1. As can be seen from fig. 1, the liquid crystal polymer prepared in example 1 has a typical cholesteric liquid crystal temperature range.
The texture of the liquid crystal polymer prepared in comparative example 1 was observed with a polarizing microscope, as shown in FIG. 2. As can be seen from fig. 2, the liquid crystal polymer prepared in the comparative example has a typical nematic liquid crystal temperature domain.
FIG. 3 is a schematic diagram showing the mechanical anisotropy mechanism of the cholesteric liquid crystal polymer prepared in example 1 and the nematic liquid crystal polymer prepared in comparative example. As can be seen from fig. 1, the cholesteric liquid crystal polymer prepared in example 1 has a helical structure; as can be seen from fig. 2, the nematic liquid crystal polymer prepared in the comparative example has a linear structure; as can be seen from fig. 3, the nematic liquid crystal polymer of the comparative example forms a preferred orientation of molecules after stretching, but the molecular chains are approximately parallel, have no helical structure, have high tensile stress in the molecular orientation direction, and have low tensile stress in the direction perpendicular to the molecular orientation direction, and have high mechanical anisotropy; after the cholesteric liquid crystal polymer prepared in the embodiment 1 is stretched, the preferential orientation of molecules can be formed, and the molecular helical arrangement can be maintained to a certain extent, so that the low mechanical anisotropy of the material is realized on the premise of ensuring the high strength and regular molecular orientation of the material.
The tensile stress of the liquid crystal polymer materials prepared in examples 1 to 4 and comparative example was measured, and the results are shown in FIG. 4.
As is clear from FIG. 4, the comparative example shows that the liquid crystal polymer has a tensile stress of 130MPa in the molecular alignment direction, and a tensile stress of only 14MPa in the perpendicular direction, and has high mechanical anisotropy. As the molar ratio of chiral groups in the raw material of the liquid crystal polymer increases, the tensile stress of the liquid crystal polymer in the molecular alignment direction gradually decreases, and the tensile stress in the direction perpendicular to the molecular alignment direction rapidly increases, as in examples 1 to 4. When the molar ratio of chiral groups is 5.26%, the tensile stress in the molecular orientation direction is 100MPa, and the tensile stress in the vertical direction is 80MPa, and the mechanical anisotropy is low.
According to the application, by introducing chiral groups, the tensile stress of the liquid crystal polymer in the direction perpendicular to the molecular orientation can be improved, so that the tensile stress in the direction of the molecular orientation is reduced, and the mechanical anisotropy of the liquid crystal polymer is reduced.
While the application has been described in detail in this specification with reference to the general description and the specific embodiments thereof, it will be apparent to one skilled in the art that modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the application and are intended to be within the scope of the application as claimed.
Claims (8)
1. A liquid crystal polymer with low mechanical anisotropy is characterized in that the repeating unit has a chemical structure shown in the following formula:
Wherein X is a rod-shaped structure formed by rigid groups;
y is a non-liquid crystal structure consisting of a flexible chain, a heterogeneous rigid group or a kinking group;
Z is a chiral group;
b. c is the molar ratio of X, Y and Z respectively, a, b, c are each independently selected from any ratio between 0.1% and 90%, and the sum of a, b and c is 100%;
The preparation method comprises the following steps:
dissolving a monomer 2, a monomer 3 and acetic anhydride in a solvent for acetylation reaction; then adding the monomer 1, and reacting at 110-130 ℃; vacuum pumping is carried out after the reaction to remove small molecules, thus obtaining the liquid crystal polymer with low mechanical anisotropy;
Or:
Mixing the monomer 2 and the monomer 3 with acetic anhydride, and performing acetylation reaction at 140-150 ℃; then adding the monomer 1, heating the reaction solution to 310-330 ℃, and vacuumizing to remove small molecules after the reaction to obtain the liquid crystal polymer with low mechanical anisotropy;
wherein the structural general formula of the monomer 1 is HOOC-X-COOH;
The general formula of the monomer 2 is HO-Y-OH;
the structural general formula of the monomer 3 is HO-Z-OH;
the solvent is N, N-dimethylamide or pyridine.
2. The liquid crystal polymer having low mechanical anisotropy according to claim 1, wherein X is selected from structures represented by formulae (1) to (10):
。
3. the liquid crystal polymer having low mechanical anisotropy according to claim 1, wherein Y is selected from structures represented by formulae (11) to (16):
wherein m and n are integers, m is more than or equal to 0, and n is more than or equal to 0.
4. The liquid crystal polymer having low mechanical anisotropy according to claim 1, wherein Z is selected from structures represented by formulae (17) to (19):
。
5. the liquid crystal polymer having low mechanical anisotropy according to claim 1, wherein,
The structural formula of X is as follows: The structural formula of Y is as follows: the structural formula of Z is: c is selected from 1.37% -5.26%.
6. The liquid crystal polymer having low mechanical anisotropy according to claim 1, wherein,
The molecular weight of the liquid crystal polymer with low mechanical anisotropy is more than 5000, and the glass transition temperature is higher than room temperature.
7. An isotropic liquid crystalline polymer material in the form of a fiber or film prepared from the liquid crystalline polymer having low mechanical anisotropy according to any one of claims 1 to 6 by extrusion molding.
8. Use of the isotropic liquid crystalline polymer material according to claim 7 in 5G antennas, high frequency communication devices, electronic devices or optical fiber packages.
Priority Applications (1)
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| DE19643277A1 (en) * | 1996-10-21 | 1998-04-23 | Clariant Gmbh | Colored cholesteric liquid crystal polymers with optically variable properties |
| JP4925709B2 (en) * | 2006-04-10 | 2012-05-09 | Ｊｘ日鉱日石エネルギー株式会社 | Liquid crystalline composition with improved adhesiveness, liquid crystal film comprising the composition, and liquid crystal display device equipped with the film |
| JP4994309B2 (en) * | 2008-06-06 | 2012-08-08 | Ｊｘ日鉱日石エネルギー株式会社 | Tilted phase difference film, method for producing tilted phase difference film, polarizing plate and liquid crystal display device |
| WO2023237572A1 (en) * | 2022-06-10 | 2023-12-14 | Merck Patent Gmbh | Polymerisable liquid crystal medium and polymerised liquid crystal film |
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