CN112457466B

CN112457466B - Preparation method of colorless and transparent high-dielectric-constant flexible polyurethane

Info

Publication number: CN112457466B
Application number: CN202011218713.7A
Authority: CN
Inventors: 梁国正; 李旦一; 顾嫒娟; 袁莉
Original assignee: Suzhou University
Current assignee: Suzhou University
Priority date: 2019-02-11
Filing date: 2019-02-11
Publication date: 2022-04-15
Anticipated expiration: 2039-02-11
Also published as: CN112457466A; CN112375199A; CN109776753B; CN112375199B; CN109776753A

Abstract

The invention discloses a preparation method of colorless and transparent high-dielectric-constant flexible polyurethane. Mixing hydroxyl-terminated polyalkylene carbonate diol, diisocyanate, 2' -dithiodiethanol, dibutyltin dilaurate and chloroalkane, and reacting to obtain isocyanate-terminated oligomer solution; adding a polyol cross-linking agent, lithium bistrifluoromethanesulfonimide and 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt into an isocyanate-terminated oligomer solution, and reacting at 40-60 ℃ for 0.5-1.5 h; after the reaction is finished, the solvent is removed, and the colorless and transparent flexible polyurethane with high dielectric constant is obtained. The polyurethane provided by the invention has high tensile strength and high elongation at break, and has outstanding bending capability and high dielectric constant.

Description

Preparation method of colorless and transparent high-dielectric-constant flexible polyurethane

The invention belongs to colorless and transparent high-dielectric-constant flexible polyurethane and a self-repairing method thereof, and divisional application of invention application with application number of 2019101104674 and application date of 2019, 2 and 11, and belongs to a part of a product preparation method.

Technical Field

The invention relates to polyurethane (polyurethane film) and a preparation method thereof, in particular to a preparation method of colorless and transparent high-dielectric-constant flexible polyurethane.

Background

Flexibility is a current trend in the development of electronic devices. Electronic devices tend to be multi-layer structures, where glass is widely used to make transparent covers for electronic devices due to its outstanding mechanical properties and colorless transparency. However, glass is rigid, resulting in a device with very limited flexibility. Although the bending ability of the glass can be improved by reducing the thickness, the height is very limited and the glass is more easily damaged, thereby greatly hindering the progress of the flexibility of the electronic device.

In the face of the great trend of electronic device flexibility, people adopt high molecular materials to replace glass to obtain flexibility, but the polycarbonate/polymethyl methacrylate (PC/PMMA) materials widely used at present have excellent optical transparency, but the flexibility is still limited, and the large-scale bending function cannot be realized. On the other hand, the polymer material used for the cover plate of the capacitive touch display screen should not only have the characteristics of no color and high transmittance, but also have a relatively high dielectric constant in order to ensure high sensitivity of the touch device. Whereas colorless and transparent polymers tend to have dielectric constants less than 4.5.

At present, a basic method for preparing a high dielectric constant polymer material is to add a conductor or high dielectric constant ceramic into a polymer, but the addition of a functional body often causes the transparent polymer to lose high transparency and change from colorless to colored, so that the condition for preparing a touch screen cannot be met.

On the other hand, the polymer material is inevitably subjected to external forces such as scraping and impact in the using process, so that the using performance of the device is reduced or the device is failed, and therefore, the research and development of the high dielectric material with the self-repairing capability have important application value while the colorless, transparent and flexible properties of the material are ensured. However, no polymeric materials having such a combination of properties have been reported to date.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides colorless and transparent flexible polyurethane with high dielectric constant, such as a polyurethane film, and a preparation method and a self-repairing method thereof. The polyurethane disclosed by the invention has the characteristics of no color, high transparency, good flexibility, high dielectric constant, self-repairing property, easiness in processing and the like, thereby having wide application prospect, in particular to a flexible capacitive touch display device.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a colorless and transparent high dielectric constant flexible polyurethane is prepared by the following steps:

(1) mixing hydroxyl-terminated polyalkylene carbonate diol, diisocyanate, 2' -dithiodiethanol, dibutyltin dilaurate and chloroalkane, and reacting at 40-60 ℃ for 0.5-3 h to obtain isocyanate-terminated oligomer solution;

(2) adding a polyol cross-linking agent, lithium bistrifluoromethanesulfonimide and 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt into an isocyanate-terminated oligomer solution, and reacting at 40-60 ℃ for 0.5-1.5 h; after the reaction is finished, the solvent is removed, and the colorless and transparent flexible polyurethane with high dielectric constant is obtained.

A preparation method of colorless and transparent high-dielectric-constant flexible polyurethane comprises the following steps:

In the invention, after the reaction is finished, the reaction solution containing polyurethane is obtained, polyurethane with various structures can be obtained by drying and removing the solvent, and polyurethane with various shapes can be obtained by changing the shape and the size of the mould, for example, a polyurethane film can be obtained by adopting a film forming mode, a polyurethane plate can be obtained by adopting a deposition mode, and the like. Preferably, after the reaction is finished, the solvent is removed from the reaction solution to form a film, and a colorless and transparent flexible polyurethane film with high dielectric constant is obtained.

The invention also discloses a self-repairing method of the colorless and transparent high-dielectric-constant flexible polyurethane film, which comprises the following steps of fixing and tightly attaching the damaged surface of the damaged colorless and transparent high-dielectric-constant flexible polyurethane film by using a clamp, and then heating the film for 0.5 to 2 hours at the temperature of 80 to 150 ℃ to complete the self-repairing of the colorless and transparent high-dielectric-constant flexible polyurethane film; the preparation method of the colorless and transparent high-dielectric-constant flexible polyurethane film comprises the following steps:

(2) adding a polyol cross-linking agent, lithium bistrifluoromethanesulfonimide and 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt into an isocyanate-terminated oligomer solution, and reacting at 40-60 ℃ for 0.5-1.5 h; and after the reaction is finished, removing the solvent from the reaction solution to form a film, thus obtaining the colorless and transparent flexible polyurethane film with high dielectric constant.

The invention further discloses application of the colorless and transparent high-dielectric-constant flexible polyurethane in preparation of high-dielectric-constant and/or self-repairing materials.

In the invention, the chloroalkane is one or the combination of dichloromethane, trichloromethane and 1, 2-dichloroethane; the diisocyanate compound is one or the combination of isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexyl methane diisocyanate; the polyalcohol crosslinking agent is one or the combination of trimethylolpropane and triethanolamine; the hydroxyl terminated polyalkylene carbonate diol has a molecular weight of 2000.

In the invention, the mass ratio of hydroxyl-terminated polyalkylene carbonate diol, diisocyanate, 2' -dithiodiethanol, dibutyltin dilaurate, a polyol crosslinking agent, lithium bistrifluoromethanesulfonylimide and 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonylimide is 100: 50-105: 23-46: 0.01-0.03: 4-11: 10-40.

Compared with the prior art, the invention has the beneficial effects that:

1. the polyurethane provided by the invention contains multiple acting forces, including dynamic ion-dipole interaction, dynamic hydrogen bond crosslinking, permanent chemical crosslinking and the like, thereby having high tensile strength and high elongation at break and having outstanding bending capability (flexibility).

2. In view of the fact that the polyurethane provided by the invention has good flexibility and is not easy to crack compared with glass and hard plastics, when the polyurethane is applied to a capacitive touch screen cover plate, the sensitivity of a capacitive touch screen can be effectively improved by reducing the thickness.

3. The polyurethane and polyurethane film provided by the invention have colorless and high-transparency optical properties, because the ionic liquid and the lithium salt have good compatibility in the polyurethane matrix, the reduction of the transparency of the material caused by phase separation and precipitation can not occur, and the material does not develop color after being dispersed in resin, so that the final material is colorless and has high transmittance.

4. The colorless and transparent high-dielectric-constant flexible polyurethane film provided by the invention realizes reversible self-repair of materials by regulating and controlling the formation/dissociation of dynamic hydrogen bonds and dynamic ion-dipole interaction and the exchange rate of disulfide bonds through temperature, and the repair effect is obvious (> 90%).

5. In the colorless and transparent high-dielectric-constant flexible polyurethane provided by the invention, the ionic liquid and the lithium salt are dispersed in the polyurethane to form a plurality of micro capacitors, so that the dielectric constant of the material is effectively improved.

6. The preparation method of the polyurethane and the polyurethane film provided by the invention has the characteristics of simple operation process, rich raw material sources, low manufacturing cost and wide applicability.

Drawings

FIG. 1 is an infrared spectrum of a colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention;

FIG. 2 is a thermogravimetric curve (nitrogen atmosphere, heating rate of 10 deg.C/min) of a colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention;

FIG. 3 is a UV-visible spectrum of a colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention;

FIG. 4 is a digital photograph of a colorless and transparent high dielectric constant flexible polyurethane film and a commercial polyimide film (which are currently widely used for flexible devices) prepared in example 1 of the present invention, folded in half, and heated by a blower (about 80 ℃ C.) for 3 min;

FIG. 5 is a tensile stress-strain curve of an intact colorless transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention and its self-healing at break;

FIG. 6 is a graph showing the effect of a digital photo of an intact colorless transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention and its fracture self-repaired film;

FIG. 7 is a graph of the bending effect of a perfect colorless transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention after self-healing of fractures;

FIG. 8 shows the dielectric constants at typical frequencies before and after self-healing of a colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention;

FIG. 9 is a photomicrograph of a colorless, transparent, high dielectric constant, flexible polyurethane film made according to example 1 of the present invention and a disulfide bond-free polyurethane film made according to comparative example 1 after breaking and after self-healing;

FIG. 10 is dielectric constants at typical frequencies for a colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention, a polyurethane film without disulfide bonds prepared in comparative example 1, and a polyurethane film without bis (trifluoromethanesulfonylimide) salt prepared in comparative example 2;

FIG. 11 is a dielectric constant-frequency curve of a colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention and a polyurethane film prepared in comparative example 2.

Detailed Description

The technical solution of the present invention is further described with reference to the accompanying drawings and examples.

Example 1

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 67g of isophorone diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 500g of methylene chloride were mixed at room temperature; then the temperature is raised to 55 ℃, and the reaction is carried out for 1h under the condition of heat preservation, thus obtaining the oligomer solution which is blocked by isocyanate and is marked as solution B.

(2) Adding 4g of trimethylolpropane, 20g of lithium bistrifluoromethanesulfonimide and 20g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt into the solution B at room temperature, and then reacting for 1h at the temperature of 60 ℃; and then pouring the mixture into a mold, drying and forming a film to obtain a colorless and transparent high-dielectric-constant flexible polyurethane film, wherein an infrared spectrum, a thermal weight loss curve, an ultraviolet-visible light spectrum, digital photos before and after folding and after heating by a blower, a tensile stress-strain curve, a digital photo for showing a curling effect and dielectric constants under typical frequencies are respectively shown in the attached

drawings

1,2, 3, 4, 5, 6, 7 and 8.

(3) The self-repairing method of the colorless, transparent and high-flexibility high-dielectric polyurethane composite material comprises the following steps: a self-repairing method after fracture. Fully contacting the fracture surfaces of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surfaces are tightly attached, and then heating for 1h at the temperature of 100 ℃. The tensile stress-strain curve, the digital picture for showing the curling effect and the dielectric constant of the polyurethane film after fracture repair are shown in the attached drawings. The microphotographs after the polyurethane film was broken and repaired are shown in FIG. 9.

Referring to FIG. 1, there is shown a schematic diagram of example 1 of the present inventionAnd the infrared spectrogram of the prepared colorless and transparent high-dielectric-constant flexible polyurethane film containing the disulfide bonds. From this, a characteristic peak of stretching vibration of-NH- (3389 cm)^-1) And bending vibration peak (1538 cm)^-1) However, the characteristic peak of-NCO (2260 cm) was not observed^-1) This indicates that isophorone diisocyanate has been reacted with 2,2' -dithiodiethanol, a hydroxyl terminated polyalkylene carbonate diol to chain extend and complete the building of a crosslinked network by reaction with trimethylolpropane.

Referring to fig. 2, it is a thermal weight loss diagram of a colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention. From this, the initial thermal decomposition temperature (temperature at 5wt% weight loss, T) of a colorless transparent high dielectric constant flexible polyurethane film was known_di) At 270 ℃ in polyurethane T_di(250 ℃ C.) and 300 ℃ C.

Referring to fig. 3, it is a uv-vis spectrum of a colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention. The transmittance of a film with the thickness of 0.2mm under the wavelength of 800nm and 300 ℃ is tested by taking air as a base line, the transmittance of the film in the range of the visible light wavelength of 780nm and 380 ℃ is more than 90.2 percent, and the transmittance of the film is equivalent to the transmittance of Corning fifth generation gorilla glass widely applied to a cover plate of a mobile phone touch screen in the market.

Referring to FIG. 4, there are shown digital photographs of colorless transparent high dielectric constant flexible polyurethane films and commercial polyimide films prepared in example 1 of the present invention as they were, after folding in half, and after heating with a blower (about 80 ℃ C.) for 3 min. It can be seen that the colorless and transparent flexible polyurethane film with high dielectric constant prepared in example 1 of the present invention has shallow crease mark after being folded in half, and can eliminate crease under the action of a blower, and the repaired sample is flat. In sharp contrast, the mark of the fold was not erased by the blower and the sample was warped after folding the polyimide film in half, indicating that the colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 did not have the disadvantages of the polyimide film.

Referring to fig. 5, it is the tensile stress-strain curve before and after the self-repairing of the colorless transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention. As can be seen, the initial tensile strength and elongation at break of the polyurethane film were 23.54. + -. 1.52 MPa and 390.6. + -. 10.24%, respectively. After repair, the tensile strength and the elongation at break of the material are respectively 22.13 +/-1.24 MPa and 358.36 +/-11.24%, and the corresponding repair efficiencies are respectively 94.01% and 91.74%.

Referring to fig. 6, it is a digital photograph of the self-healing effect of the colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention. As shown in the figure, the complete colorless and transparent high-dielectric constant flexible polyurethane film is cut off, and the sections are tightly attached together; and then keeping the temperature at 100 ℃ for 1h, and reconnecting the completely broken two-part film into a whole, wherein the repaired material still has excellent optical transparency.

Referring to fig. 7, it is a digital photograph showing the curling and bending effects before and after the repair of the colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention. As can be seen, the intact original polyurethane film was able to be bent into an S-shape and achieved a curl, with better flexibility than PMMA. In addition, the self-repaired polyurethane film still keeps excellent flexibility.

Referring to FIG. 8, the dielectric constants of the colorless transparent high dielectric constant flexible polyurethane film prepared in example 1 of the present invention at typical frequencies before and after self-healing are shown. It can be seen that the dielectric constant of the material at different frequencies remains substantially unchanged after the heating treatment, indicating that the self-repairing effect of the material is excellent.

Comparative example 1

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 67g of isophorone diisocyanate, 24g of 1, 6-hexanediol, 0.02g of dibutyltin dilaurate and 500g of methylene chloride were mixed at room temperature; after heating to 60 ℃, the reaction was carried out for 1.5h with heat preservation to obtain an isocyanate terminated polycarbonate solution without disulfide bonds, which was designated as solution C.

(2) Adding 4g of trimethylolpropane, 20g of lithium bistrifluoromethanesulfonimide and 20g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution C at room temperature, and then reacting at 60 ℃ for 1 hour; then pouring into a mould, and drying to obtain the polyurethane film, wherein the dielectric constant-frequency diagram of the polyurethane film is shown in figure 10.

(3) And fully contacting two sections of the damaged polyurethane film to ensure that the two sections are tightly attached, then heating at 100 ℃ for 1h for repairing, wherein micrographs of the broken film and the repaired film are shown in figure 9, after treatment, the sections can not be bonded, and the repairing efficiency is 0. Since there is no repair, the dielectric constant after repair cannot be tested under the same conditions.

Referring to FIG. 9, there are shown photomicrographs of the colorless, transparent, high dielectric constant, flexible polyurethane film (0.2 mm thick) prepared in example 1 of the present invention and the polyurethane film (0.2 mm thick) prepared in comparative example 1 after breaking and after self-healing. A section with the width of about 50 mu m is manufactured on the surface of a colorless and transparent high-dielectric-constant flexible polyurethane film by using a surgical blade, the section is placed on a hot table at 100 ℃ to be heated for 1h after being effectively contacted, and after the repair is finished, the originally strip-shaped opaque black area becomes transparent and only a little scar similar to the healed human wound is left. In contrast, the polyurethane film prepared in comparative example 1 did not achieve crack healing and the black stripe areas did not disappear under the same repair conditions, which indicates that even if the temperature was raised to 100 ℃, the mobility of the segments of the material was still greatly limited due to the presence of the permanent chemical cross-linking network. The novel colorless and transparent high dielectric constant flexible polyurethane film disclosed by the invention can be self-repaired.

Comparative example 2

(1) Solution B was prepared according to the procedure in example 1.

(2) At room temperature, 4g of trimethylolpropane is added to the solution B, and then the mixture is reacted at 60 ℃ for 1 hour, poured into a mold and dried to obtain a polyurethane film, and the dielectric constant-frequency curve of the polyurethane film is shown in FIG. 10.

(3) The self-repairing method of the polyurethane film comprises the following steps: a self-repairing method after fracture. And fully contacting the fracture surfaces of the colorless and transparent polyurethane film to ensure that the fracture surfaces are tightly attached, and then heating for 1h at the temperature of 100 ℃. The tensile strength and the elongation at break of the finished film are 26.45 +/-2.40 MPa and 358.24 +/-9.5 percent respectively, and the tensile strength and the elongation at break of the repaired film are 23.35 +/-4.22 MPa and 321.55 +/-12.5 percent respectively, so that the repairing efficiency of the tensile strength and the elongation at break is 88.28 percent and 89.75 percent respectively.

Referring to fig. 10 and 11, there are shown dielectric constants of colorless and transparent high dielectric constant flexible polyurethane films prepared in example 1 of the present invention, polyurethane films prepared in comparative example 1, and polyurethane films prepared in comparative example 2 at typical frequencies. It can be seen that the colorless and transparent high dielectric constant flexible polyurethane film prepared in example 1 has dielectric constants of 109.7, 7.4 and 6.5 at 100Hz, 500kHz and 1MHz, which are improved by 32 times, 1.8 times and 1.7 times as compared with the polyurethane film prepared in comparative example 2.

Example 2

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 50g of hexamethylene diisocyanate, 23g of 2,2' -dithiodiethanol, 0.01g of dibutyltin dilaurate, 500g of methylene chloride and 500g of chloroform were mixed at room temperature; then heating to 60 ℃ and then keeping the temperature to react for 0.5h to obtain an isocyanate-terminated oligomer solution which is marked as solution D.

(2) Adding 9g of trimethylolpropane, 10g of lithium bistrifluoromethanesulfonimide and 40g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution D at room temperature, and then reacting at 60 ℃ for 1 hour; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. The fracture surfaces of the colorless and transparent high-dielectric-constant flexible polyurethane film are fully contacted to ensure that the film is tightly attached, then the film is heated for 2 hours at the temperature of 80 ℃, the two completely fractured parts of the film are connected into a whole again, the repaired material still has excellent optical transparency, and the repair efficiencies corresponding to the tensile strength and the elongation at break of the material are 93.89% and 91.12% respectively.

Example 3

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 105g of cyclohexylmethane diisocyanate, 35g of 2,2' -dithiodiethanol, 0.03g of dibutyltin dilaurate, 300g of methylene chloride and 300g of 1, 2-dichloroethane were mixed at room temperature; then heating to 60 ℃ and then keeping the temperature for reaction for 1h to obtain an isocyanate-terminated oligomer solution which is marked as solution E.

(2) Adding 11g of trimethylolpropane, 40g of lithium bistrifluoromethanesulfonimide and 30g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution E at room temperature, and then reacting at 40 ℃ for 1 hour; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating for 0.5h at the temperature of 150 ℃.

Example 4

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 33g of isophorone diisocyanate and 25g of hexamethylene diisocyanate, 31g of 2,2' -dithiodiethanol, 0.01g of dibutyltin dilaurate and 500g of methylene chloride and 300g of chloroform were mixed at room temperature; then the temperature is raised to 40 ℃ and the reaction is carried out for 3 hours under the condition of heat preservation, thus obtaining the oligomer solution which is blocked by isocyanate and is marked as solution F.

(2) Adding 4g of trimethylolpropane, 25g of lithium bistrifluoromethanesulfonimide and 10g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution F at room temperature, and then reacting at 60 ℃ for 0.5 h; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating the film for 1.2 hours at the temperature of 120 ℃.

Example 5

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 33g of isophorone diisocyanate and 39g of dicyclohexylmethane diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 1500g of methylene chloride were mixed at room temperature; then heating to 60 ℃ and then keeping the temperature for reaction for 1h to obtain an isocyanate-terminated oligomer solution which is marked as solution G.

(2) Adding 4G of trimethylolpropane, 25G of lithium bistrifluoromethanesulfonimide and 25G of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution G at room temperature, and then reacting at 60 ℃ for 1 hour; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surfaces of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surfaces are tightly attached, and then heating for 1h at the temperature of 100 ℃.

Example 6

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 22g of isophorone diisocyanate, 17g of hexamethylene diisocyanate and 26g of dicyclohexylmethane diisocyanate, 31g of 2,2' -dithiodiethanol, 0.03g of dibutyltin dilaurate, 500g of dichloromethane and 300g of trichloromethane were mixed at room temperature; then heating to 55 ℃, and then keeping the temperature to react for 1H to obtain an isocyanate-terminated oligomer solution which is marked as solution H.

(2) Adding 4g of trimethylolpropane, 30g of lithium bistrifluoromethanesulfonimide and 25g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution H at room temperature, and then reacting at 60 ℃ for 0.5H; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surfaces of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surfaces are tightly attached, and then heating the film for 1.2 hours at the temperature of 100 ℃.

Example 7

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 67g of isophorone diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 500g of methylene chloride were mixed at room temperature; then heating to 40 ℃ and then keeping the temperature for reaction for 3h to obtain an isocyanate-terminated oligomer solution which is marked as solution I.

(2) Adding 5g of triethanolamine, 20g of lithium bistrifluoromethanesulfonimide and 20g of 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt into the solution I at room temperature, and then reacting for 1.5h at the temperature of 45 ℃; and then pouring the mixture into a mold, and drying to obtain a colorless and transparent high-dielectric-constant flexible polyurethane film, wherein the dielectric constants of the polyurethane film under 100Hz, 500kHz and 1MHz are 102.9, 7.3 and 6.4 respectively.

Example 8

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 67g of isophorone diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 500g of methylene chloride were mixed at room temperature; then the temperature is raised to 55 ℃ and the reaction is carried out for 2.5h under the condition of heat preservation, thus obtaining the oligomer solution which is blocked by isocyanate and is marked as solution J.

(2) Adding 2g of trimethylolpropane, 2.5g of triethanolamine, 20g of lithium bistrifluoromethanesulfonimide and 20g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution J at room temperature, and then reacting at 60 ℃ for 1.5 hours; and then pouring the mixture into a mold, and drying to obtain a colorless and transparent high-dielectric-constant flexible polyurethane film, wherein the dielectric constants of the polyurethane film at 100Hz, 500kHz and 1MHz are 106.7, 7.3 and 6.1 respectively.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. The fracture surfaces of the colorless and transparent high-dielectric-constant flexible polyurethane film are fully contacted to ensure that the film is tightly attached, then the film is heated for 1.5 hours at the temperature of 100 ℃, the two completely fractured films are connected into a whole again, the repaired material still has excellent optical transparency, and the repair efficiencies corresponding to the tensile strength and the elongation at break of the material are 93.15 percent and 91.06 percent respectively.

Example 9

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 79g of dicyclohexylmethane diisocyanate, 31g of 2,2' -dithiodiethanol, 0.01g of dibutyltin dilaurate, 850g of methylene chloride and 160g of 1, 2-dichloroethane were mixed at room temperature; then heating to 55 ℃, and then keeping the temperature to react for 2 hours to obtain an isocyanate terminated oligomer solution which is marked as solution K.

(2) Adding 5g of triethanolamine, 25g of lithium bistrifluoromethanesulfonimide and 20g of 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt into the solution K at room temperature, and then reacting for 1h at the temperature of 40 ℃; and then pouring the mixture into a mold, and drying to obtain a colorless and transparent flexible polyurethane film with high dielectric constant, wherein the dielectric constants under 100Hz, 500kHz and 1MHz are 103.3, 7.5 and 6.4 respectively.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surfaces of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surfaces are tightly attached, and then heating for 1.2h at the temperature of 96 ℃.

Example 10

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 79g of dicyclohexylmethane diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate, 150g of trichloromethane and 875g of methylene chloride were mixed at room temperature; then heating to 60 ℃ and then keeping the temperature to react for 1.5h to obtain the oligomer solution which is blocked by isocyanate and is marked as solution L.

(2) Adding 5g of triethanolamine, 10g of lithium bistrifluoromethanesulfonimide and 10g of 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt into the solution L at room temperature, and then reacting for 0.75h at the temperature of 60 ℃; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating for 1h at the temperature of 108 ℃.

Example 11

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 50g of hexamethylene diisocyanate, 31g of 2,2' -dithiodiethanol, 0.03g of dibutyltin dilaurate, 175g of 1, 2-dichloroethane and 915g of chloroform were mixed at room temperature; then heating to 60 ℃ and then keeping the temperature to react for 0.5h to obtain the oligomer solution of the end capping of the isocyanate, which is marked as solution M.

(2) Adding 5g of triethanolamine, 12.5g of lithium bistrifluoromethanesulfonimide and 15g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt into the solution M at room temperature, and then reacting for 1.25h at 55 ℃; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

Example 12

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 79g of dicyclohexylmethane diisocyanate, 31g of 2,2' -dithiodiethanol, 0.01g of dibutyltin dilaurate, 500g of dichloromethane, 500g of chloroform and 500g of 1, 2-dichloroethane were mixed at room temperature; then heating to 45 ℃ and then keeping the temperature to react for 2.5h to obtain the oligomer solution with the end capped by isocyanate, which is marked as solution N.

(2) Adding 5g of triethanolamine, 15g of lithium bistrifluoromethanesulfonimide and 17.5g of 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt into the solution N at room temperature, and then reacting for 0.8h at the temperature of 60 ℃; and then pouring the mixture into a mold, and drying to obtain a colorless and transparent flexible polyurethane film with high dielectric constant, wherein the dielectric constants under 100Hz, 500kHz and 1MHz are 101.7, 6.0 and 5.9 respectively.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. The fracture surfaces of the colorless and transparent high-dielectric-constant flexible polyurethane film are fully contacted to ensure that the film is tightly attached, then the film is heated for 0.75h at the temperature of 143 ℃, the two completely fractured films are connected into a whole again, the repaired material still has excellent optical transparency, and the repair efficiencies corresponding to the tensile strength and the fracture elongation of the material are 92.98% and 91.02% respectively.

Example 13

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 50g of hexamethylene diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 1200g of methylene chloride were mixed at room temperature; then heating to 50 ℃ and keeping the temperature to react for 0.5h to obtain the oligomer solution blocked by the isocyanate, which is marked as solution O.

(2) Adding 5g of triethanolamine, 17.5g of lithium bistrifluoromethanesulfonimide and 12.5g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution O at room temperature, and then reacting at 50 ℃ for 1 hour; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating for 1.2h at the temperature of 90 ℃.

Example 14

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 50g of hexamethylene diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 740g of chloroform were mixed at room temperature; then heating to 60 ℃ and then keeping the temperature for reaction for 1h to obtain an isocyanate-terminated oligomer solution which is marked as solution P.

(2) Adding 2g of trimethylolpropane, 2.5g of triethanolamine, 15g of lithium bistrifluoromethanesulfonimide and 30g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution P at room temperature, and then reacting at 55 ℃ for 1.5 hours; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating for 1.25h at the temperature of 100 ℃.

Example 15

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 79g of dicyclohexylmethane diisocyanate, 31g of 2,2' -dithiodiethanol, 0.01g of dibutyltin dilaurate and 1050g of methylene chloride were mixed at room temperature; then heating to 60 ℃ and then keeping the temperature for reaction for 1h to obtain an isocyanate-terminated oligomer solution which is marked as a solution Q.

(2) Adding 2g of trimethylolpropane, 2.5g of triethanolamine, 20g of lithium bistrifluoromethanesulfonimide and 20g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution Q at room temperature, and then reacting at 48 ℃ for 1.25 hours; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating for 1h at the temperature of 115 ℃.

Example 16

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 33g of isophorone diisocyanate and 25g of hexamethylene diisocyanate, 31g of 2,2' -dithiodiethanol, 0.01g of dibutyltin dilaurate and 1025g of 1, 2-dichloroethane were mixed at room temperature; then heating to 50 ℃ and keeping the temperature to react for 1.5h to obtain the oligomer solution of the end capping of the isocyanate, which is marked as solution R.

(2) Adding 5g of triethanolamine, 15g of lithium bistrifluoromethanesulfonimide and 15g of 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt into the solution R at room temperature, and then reacting for 0.75h at the temperature of 56 ℃; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating for 0.8h at the temperature of 120 ℃.

Example 17

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 33g of isophorone diisocyanate and 39g of dicyclohexylmethane diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 760g of methylene chloride were mixed at room temperature; then heating to 57 ℃, and then preserving the temperature for 1h to obtain an isocyanate-terminated oligomer solution which is marked as solution S.

(2) Adding 1.25g of triethanolamine, 3g of trimethylolpropane, 20g of lithium bistrifluoromethanesulfonimide and 20g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution S at room temperature, and then reacting at 60 ℃ for 0.5 h; and then pouring the mixture into a mold, and drying to obtain a colorless and transparent flexible polyurethane film with high dielectric constant, wherein the dielectric constants of the polyurethane film under 100Hz, 500kHz and 1MHz are 105.9, 7.2 and 6.2 respectively.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating for 0.75h at the temperature of 150 ℃.

Example 18

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 22g of isophorone diisocyanate, 17g of hexamethylene diisocyanate and 26g of dicyclohexylmethane diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 645g of trichloromethane were mixed at room temperature; then heating to 65 ℃ and then keeping the temperature for reaction for 1h to obtain an isocyanate-terminated oligomer solution which is marked as a solution T.

(2) Adding 1.25g of triethanolamine, 3g of trimethylolpropane, 25g of lithium bistrifluoromethanesulfonimide and 25g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution T at room temperature, and then reacting at 55 ℃ for 1 hour; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating for 1.5h at the temperature of 80 ℃.

Example 19

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 67g of isophorone diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 765g of methylene chloride were mixed at room temperature; then heating to 60 ℃ and then keeping the temperature for reaction for 1h to obtain an isocyanate-terminated oligomer solution which is marked as solution U.

(2) 4g of trimethylolpropane, 12.5g of lithium bistrifluoromethanesulfonimide and 12.5g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt were added to the solution U at room temperature, followed by reaction at 46 ℃ for 0.75 h; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surface of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surface is tightly attached, and then heating for 0.75h at the temperature of 128 ℃.

Example 20

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 89g of isophorone diisocyanate, 46g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 800g of methylene chloride were mixed at room temperature; then the temperature is raised to 58 ℃ and the reaction is carried out for 3h under the condition of heat preservation, thus obtaining the oligomer solution which is blocked by isocyanate and is marked as solution V.

(2) Adding 4g of trimethylolpropane, 16g of lithium bistrifluoromethanesulfonimide and 19g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt to the solution V at room temperature, and then reacting at 60 ℃ for 0.5 h; and then pouring the mixture into a mold, and drying to obtain a colorless and transparent flexible polyurethane film with high dielectric constant, wherein the dielectric constants under 100Hz, 500kHz and 1MHz are 104.8, 7.2 and 6.0 respectively.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. Fully contacting the fracture surfaces of the colorless and transparent high-dielectric constant flexible polyurethane film to ensure that the fracture surfaces are tightly attached, and then heating for 1h at the temperature of 110 ℃.

Example 21

(1) 100g of a hydroxyl-terminated polyalkylene carbonate diol (molecular weight 2000), 67g of isophorone diisocyanate, 31g of 2,2' -dithiodiethanol, 0.02g of dibutyltin dilaurate and 855g of methylene chloride were mixed at room temperature; then the temperature is raised to 55 ℃, and the reaction is carried out for 1.5h under the condition of heat preservation, thus obtaining the oligomer solution which is blocked by isocyanate and is marked as solution W.

(2) 4g of trimethylolpropane, 22.5g of lithium bistrifluoromethanesulfonimide and 15.5g of 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonimide salt were added to the solution W at room temperature, followed by reaction at 52 ℃ for 1.5 hours; and then pouring the mixture into a mold, and drying to obtain the colorless and transparent high-dielectric-constant flexible polyurethane film.

(3) The self-repairing method of the colorless, transparent and highly flexible high-dielectric polyurethane composite material is a self-repairing method after fracture. The fracture surfaces of the colorless and transparent high-dielectric-constant flexible polyurethane film are fully contacted to ensure that the film is tightly attached, then the film is heated for 1.5 hours at the temperature of 99 ℃, the two completely fractured films are connected into a whole again, the repaired material still has excellent optical transparency, and the repair efficiencies corresponding to the tensile strength and the fracture elongation of the material are respectively 92.59 percent and 91.07 percent.

The polyurethane film provided by the invention has multiple functions, and under room temperature, the film has multi-scale acting forces such as ion-dipole action, dynamic cross-linking of hydrogen bonds, permanent chemical cross-linking and the like, so that the film has high mechanical strength and high flexibility; under the heating condition, the ion-dipole and the hydrogen bond are dissociated, the exchange rate of disulfide bonds is accelerated, and the structural changes enable the polyurethane to have good reversible self-repairing performance. In the polyurethane film prepared by the invention, the ionic liquid/lithium salt and the polymer matrix have good compatibility and do not develop color, and the modified polyurethane does not develop color and does not reduce the transmittance caused by component phase separation or precipitation. Particularly, the polyurethane film prepared by the invention has high dielectric property on the basis of transparency, solves the problem of poor dielectric property of the existing transparent film, and the lithium salt and the ionic liquid which are effectively dispersed in the polymer matrix construct a plurality of micro-capacitors, thereby greatly improving the dielectric constant of the material. In addition, the preparation method of the polyurethane film has the characteristics of wide raw material source, simple process, good product applicability and strong practicability.

Claims

1. A preparation method of colorless and transparent flexible polyurethane with high dielectric constant is characterized by comprising the following steps:

(2) adding a polyol cross-linking agent, lithium bistrifluoromethanesulfonimide and 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt into an isocyanate-terminated oligomer solution, and reacting at 40-60 ℃ for 0.5-1.5 h; after the reaction is finished, removing the solvent to obtain colorless and transparent flexible polyurethane with high dielectric constant;

the mass ratio of the hydroxyl-terminated polyalkylene carbonate diol to the diisocyanate to the 2,2' -dithiodiethanol to the dibutyltin dilaurate to the polyol crosslinking agent to the lithium bistrifluoromethanesulfonimide to the 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt is 100: 50-105: 23-46: 0.01-0.03: 4-11: 10-40.

2. The method of preparing the colorless and transparent flexible polyurethane with high dielectric constant as claimed in claim 1, wherein: the chloroalkane is one or the combination of dichloromethane, trichloromethane and 1, 2-dichloroethane; the diisocyanate compound is one or the combination of isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexyl methane diisocyanate; the polyalcohol crosslinking agent is one or the combination of trimethylolpropane and triethanolamine; the hydroxyl terminated polyalkylene carbonate diol has a molecular weight of 2000.

3. The method of preparing the colorless and transparent flexible polyurethane with high dielectric constant as claimed in claim 1, wherein: in the step (2), after the reaction is finished, removing the solvent from the reaction solution to form a film, and obtaining the colorless and transparent flexible polyurethane film with high dielectric constant.

4. The method of preparing the colorless and transparent flexible polyurethane with high dielectric constant of claim 3, wherein: and removing the solvent by adopting a drying mode.