Cathode electrochromic material for automobile reflective mirror

Abstract

A preparation method of the cathode electrochromic material comprises the following steps: dissolving 0.1 mol of 4, 4 '-dipyridyl and 0.1 mol of bromobenzene in 250 ml of acetonitrile solution, heating and refluxing for 24 hours while stirring, cooling in a refrigerator, and filtering after crystals are separated out to obtain about 0.075 mol of 4-benzene ring 4, 4'-dipyridyl derivative (I); carrying out a replacement reaction on 0, 05 mol of the 4-benzene ring 4, 4 '-dipyridyl derivative (I) and 0.05 mol of alkali metal salt in water to obtain a 4, 4'-dipyridyl disubstituted derivative (II); the preparation method comprises the following steps: dissolving a 4, 4 '-dipyridyl disubstituted derivative (II), 0.001 to 0.5 M of dimethyl phenazine and 0.05 to 5 weight percent of polymethyl methacrylate into a propylene carbonate solution; the method has the advantages that substituent groups on viologen adopt benzene ring structures, and the electrified coloring degree is improved, so that the use amount of the viologen is reduced, the cost is saved, and the service life of the product is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of automobile reflector manufacturing, in particular to a cathode electrochromic material used on an automobile reflector. Background Art

[0002] Electrochromism refers to the phenomenon that when driven by an external voltage or current, a substance undergoes an electrochemical redox reaction that causes a color change. That is, under the action of an external electric field, the chemical properties of the substance (transmittance, reflectivity, etc.) undergo stable and reversible changes within the visible light range.

[0003] There is a Chinese invention patent with the patent number CN202080027425.5 and the name "Low-dimerization viologen electrochromic compound and device" which discloses a low-dimerization electrochromic compound used in an electrochromic medium and an electro-optical element including the electrochromic medium. The low-dimerization electrochromic compound is represented by formula (I):

[0004]

[0005] Each R1 is independently an alkyl, a hydroxyalkyl or an alkyl substituted by at least one polymerizable functional group; each R2 is hydrogen; each R3 is independently hydrogen or an alkyl; and each R4 is independently hydrogen, an alkyl or a hydroxyalkyl; and X- is an anion. However, the electrification coloring effect of the material still has room for improvement, so the material needs to be further improved. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a cathode electrochromic material for automobile reflectors, which can save the production cost of electrochromic materials and has good coloring effect when the material is electrified, in view of the above-mentioned existing technical status.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: the cathode electrochromic material used for automobile reflectors is characterized in that: its preparation method comprises the following steps:

[0008] 1. Dissolve 0.1 mol of 4,4'-bipyridine and 0.1 mol of bromobenzene in 250 ml of acetonitrile solution, heat and reflux for 24 hours under stirring, cool in a refrigerator, filter after crystals precipitate, and obtain about 0.075 mol of 4-phenyl ring 4,4'-bipyridine derivative (Ⅰ);

[0009] 2. 0.05 mol of the above 4-phenyl ring 4,4'-bipyridine derivative (I) is subjected to a displacement reaction with 0.05 mol of an alkali metal salt in water to obtain a 4,4'-bipyridine disubstituted derivative (II);

[0010] 3. Dissolve 4,4'-bipyridine disubstituted derivative (II), 0.001-0.5M dimethylphenazine, and 0.05-5wt% polymethyl methacrylate in propylene carbonate solution.

[0011] As an improvement, in step 1, the structural formula of the 4-phenyl ring 4,4'-bipyridine derivative (Ⅰ) is,

[0012]

[0013] As an improvement, in step 2, the alkali metal salt may preferably be a sodium salt or a lithium salt.

[0014] Further improvement, in step 2, when sodium salt is used, the sodium salt refers to NaR1, wherein R1 refers to ClO4 - , BF4 - , PF4 - , one of (CFSO3)N, (CFCFSO)N.

[0015] Further improvement, in step 2, when lithium salt is used, the lithium salt refers to LiR1, wherein R1 refers to ClO4 - , BF4 - , PF4 - , (CFSO3)N, (CFCFSO)N

[0016] As an improvement, in step 2, the structural formula of the 4,4'-bipyridine disubstituted derivative (II) is:

[0017]

[0018] Where X is Na or Li, R1 is ClO4 - , BF4 - , PF4 - , one of (CFSO3)N, (CFCFSO)N.

[0019] As an improvement, in step three, an additive that can accelerate the movement of electrons in the liquid may be preferably added to the prepared solution.

[0020] As a further improvement, the additive may preferably be ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt.

[0021] As a further improvement, the molar ratio of the additive to the disubstituted 4,4'-bipyridine derivative (II) may preferably be 0.8 to 1.5.

[0022] Further improvement, the structural formula of the ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt is:

[0023]

[0024] Compared with the prior art, the advantages of the present invention are as follows: the substituent of the viologen is changed from the traditional straight-chain alkane to a benzene ring, which can effectively improve the coloring degree of the material; the coloring effect of the benzene ring group on the viologen when electrified is 2 to 3 times that of the straight-chain alkane, thereby greatly reducing the usage of the viologen and saving the production cost of the electrochromic material; because the amount of viologen added is reduced when the same color-changing effect is achieved, the electron migration phenomenon caused by material aggregation when the product is electrified for a long time is more effectively reduced; with the aid of suitable additives, such as plasma, the movement of electrons can be accelerated, and the aggregation of the color-changing material can be reduced after the product is electrified for a long time, thereby extending the service life of the product and achieving a good use effect. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with specific embodiments.

[0026] The cathode electrochromic material used for the automobile reflector of this embodiment is prepared by a method comprising the following steps:

[0027] 1. Dissolve 0.1 mol of 4,4'-bipyridine and 0.1 mol of bromobenzene in 250 ml of acetonitrile solution, heat and reflux for 24 hours under stirring, cool in a refrigerator, filter after crystals precipitate, and obtain about 0.075 mol of 4-phenyl ring 4,4'-bipyridine derivative (Ⅰ);

[0028] 2. 0.05 mol of the above 4-phenyl ring 4,4'-bipyridine derivative (I) is subjected to a displacement reaction with 0.05 mol of an alkali metal salt in water to obtain a 4,4'-bipyridine disubstituted derivative (II);

[0029] 3. Dissolve 4,4'-bipyridine disubstituted derivative (II), 0.001-0.5M dimethylphenazine, and 0.05-5wt% polymethyl methacrylate (PMMA) in propylene carbonate solution.

[0030] In step 1, the structural formula of the 4-phenyl ring 4,4'-bipyridine derivative (Ⅰ) is:

[0031]

[0032] In step 2, the alkali metal salt may be preferably a sodium salt or a lithium salt. When a sodium salt is used, the sodium salt refers to NaR1, and when a lithium salt is used, the lithium salt refers to LiR1, wherein R1 refers to ClO4 - , BF4 - , PF4 - , one of (CFSO3)N, (CFCFSO)N.

[0033] The structural formula of the disubstituted 4,4'-bipyridine derivative (II) is:

[0034]

[0035] Where X is Na or Li, R1 is ClO4 - , BF4 - , PF4 - , one of (CFSO3)N, (CFCFSO)N.

[0036] In step 3, an additive that can accelerate the electron migration in the liquid is added to the prepared solution. The additive is ethyl-3-methylimidazolium bis-trifluoromethanesulfonyl imide salt. The molar ratio of the additive to the 4,4'-bipyridine disubstituted derivative (II) is 0.8 to 1.5. The structural formula of ethyl-3-methylimidazolium bis-trifluoromethanesulfonyl imide salt is,

[0037]

[0038] The following table shows the comparison of the optical data of the final product and the viologen substituent as a straight-chain alkane. It can be seen that the substituent as a benzene ring can greatly improve the coloring degree, thereby effectively reducing the amount of viologen used.

[0039] Table 3.1 Optical data of bipyridyl radical cations.

[0040]

Claims

1. A cathode electrochromic material for automobile reflectors, characterized in that: The preparation method thereof comprises the following steps:

1. Dissolve 0.1 mol of 4,4'-bipyridine and 0.1 mol of bromobenzene in 250 ml of acetonitrile solution, heat and reflux for 24 hours under stirring, cool in a refrigerator, filter after crystals precipitate, and obtain about 0.075 mol of 4-phenyl ring 4,4'-bipyridine derivative (Ⅰ); 2. 0.05 mol of the above 4-phenyl ring 4,4'-bipyridine derivative (I) is subjected to a displacement reaction with 0.05 mol of an alkali metal salt in water to obtain a 4,4'-bipyridine disubstituted derivative (II); 3. Dissolve 4,4'-bipyridine disubstituted derivative (II), 0.001-0.5M dimethylphenazine, and 0.05-5wt% polymethyl methacrylate in propylene carbonate solution.

2. The cathode electrochromic material according to claim 1, characterized in that: In step 1, the structural formula of the 4-phenyl ring 4,4'-bipyridine derivative (Ⅰ) is:

3. The cathode electrochromic material according to claim 1, characterized in that: In step 2, the alkali metal salt is a sodium salt or a lithium salt.

4. The cathode electrochromic material according to claim 3, characterized in that: In step 2, when sodium salt is used, the sodium salt refers to NaR1, wherein R1 refers to ClO4 - , BF4 - , PF4 - , one of (CFSO3)N, (CFCFSO)N.

5. The cathode electrochromic material according to claim 3, characterized in that: In step 2, when a lithium salt is used, the lithium salt refers to LiR1, wherein R1 refers to ClO4 - , BF4 - , PF4 - , one of (CFSO3)N, (CFCFSO)N.

6. The cathode electrochromic material according to any one of claims 3 to 5, characterized in that: In step 2, the structural formula of the 4,4'-bipyridine disubstituted derivative (II) is: Where X is Na or Li, R1 is ClO4 - , BF4 - , PF4 - , one of (CFSO3)N, (CFCFSO)N.

7. The cathode electrochromic material according to claim 1, characterized in that: In step three, an additive that can accelerate the movement of electrons in the liquid is added to the prepared solution.

8. The cathode electrochromic material according to claim 7, characterized in that: The additive is ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt.

9. The cathode electrochromic material according to claim 8, characterized in that: The molar ratio of the additive to the 4,4'-bipyridine disubstituted derivative (II) is 0.8 to 1.

5.

10. The cathode electrochromic material according to claim 8, characterized in that: The structural formula of the ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is:

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