CN109293821B - A kind of dye-doped liquid crystal microcapsule material and preparation method thereof - Google Patents

Abstract

The invention discloses a preparation method of a dye-doped liquid crystal microcapsule, belonging to the technical field of fine chemical engineering and material science. The dye-doped liquid crystal prepared by the method has a multilayer structure, the outer dye-doped liquid crystal and the polymer shell layer are used as color development layers to be subjected to subtractive color matching with the core material dye-doped liquid crystal microcapsule, and are simultaneously used as protective layers to protect the inner dye-doped liquid crystal from being polluted by the external environment. The liquid crystal microcapsule prepared by the method has the advantages of gorgeous and variable color, low driving voltage, good solvent resistance and water resistance, original color performance after processing treatment, capability of meeting the requirements of people on individuation and diversity of liquid crystal color development in flexible display and intelligent textiles, and wide application prospect.

Description

A kind of dye-doped liquid crystal microcapsule material and preparation method thereof

technical field

The invention belongs to the technical fields of fine chemical industry and material science, and particularly relates to a dye-doped liquid crystal microcapsule material and a preparation method thereof.

Background technique

Liquid crystal displays are widely used in practice due to their excellent optical properties and electro-optical effects. At the same time, in order to expand the application of liquid crystal in specific needs, such as flexible display technology, smart fiber preparation, etc., the liquid crystal microencapsulation process has played a crucial role in this. On the one hand, the dispersion, protection and stabilization of the liquid crystal are realized through the coating, which prevents the liquid crystal from flowing during the deflection process of the device, thereby ensuring the feasibility of flexible liquid crystal display; on the other hand, by controlling the size and size of the microcapsules and distribution to adjust the size of liquid crystal droplets in the system, thereby improving the electro-optical performance of the display device. In recent years, Hanyang University has made great breakthroughs in liquid crystal microcapsules and explored the application of nematic liquid crystal microcapsule products in PDLC. Fuji Xerox Co., Ltd reported a class of liquid crystal microcapsules with an internal alignment layer structure. By regulating the molecular arrangement of liquid crystal droplets inside the microcapsules, the LC/polymer system exhibits good electro-optical properties, and the device displays a high contrast ratio. 40:1. Jiangnan University Guan Yu et al. prepared cholesteric liquid crystal microcapsules by complex coagulation method, and prepared thermochromic smart fibers with a response temperature between 35-38 °C by electrospinning technology.

However, the reports on liquid crystal microencapsulation so far are mainly concentrated in a few regions and companies, and the preparation method of liquid crystal microcapsules is mainly based on the shell-core structure. For the electrochromic liquid crystal microcapsules prepared by these methods, when cholesteric liquid crystal is used as the core material, the driving voltage of the liquid crystal microcapsule is higher; however, when the dichroic dye-doped nematic liquid crystal is used as the core material, it cannot be achieved Multi-colored color rendering of a single liquid crystal microcapsule; if a variety of single color changing liquid crystal microcapsules are used in combination, due to the difference in the particle size of the liquid crystal microcapsules, the light scattering effect is obvious, and the color rendering effect is not good. Therefore, how to prepare a liquid crystal microcapsule with excellent physicochemical and optical properties and satisfying low driving voltage and colorful color-changing properties is an urgent problem to be solved in the industry.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention designs a dye-doped liquid crystal microcapsule with a multi-layer structure, and realizes a liquid crystal microcapsule with good light transmittance, high mechanical strength and chemical corrosion resistance prepared by using nematic liquid crystal. At the same time, the liquid crystal microcapsules need to meet the lower driving voltage and colorful electrochromic ability. The specific preparation method of the multi-layer structure dye-doped liquid crystal microcapsules was explored. By screening suitable monomers, liquid crystals, dichroic dyes and surfactants, the multi-layer structure dye-doped type was prepared by seed emulsion polymerization. Liquid crystal microcapsules.

The first object of the present invention is to provide a method for preparing dye-doped liquid crystal microcapsules, the method comprising:

(1) fully mixing the dichroic dye and the nematic liquid crystal to prepare dye-doped liquid crystal materials with different color changes respectively;

(2) Mix the organic monomers of one color dye-doped liquid crystal material evenly. The organic monomers include soft monomers, hard monomers, cross-linking monomers and organic monomers with low surface energy and high adhesion. Add Non-ionic surfactants make uniformly dispersed emulsion dispersions;

(3) adding an initiator to initiate polymerization to prepare liquid crystal microcapsules of polymer-coated dye-doped liquid crystal material, and purifying the emulsion after the reaction to obtain a dye-doped liquid crystal microcapsule emulsion with uniform particle size distribution;

(4) using the dye-doped liquid crystal microcapsules prepared in the above (3) as seeds, mixing another dye-doped liquid crystal material with a different color with a soft monomer and a hard monomer to obtain an oil phase and adding it to the emulsion, The mass fraction of the soft monomer to the hard monomer is 50-200%, and the temperature (warming up to the cloud point of the surfactant first, and then cooling down to the emulsification temperature) and rotational speed are controlled, so that the binding ability of the surfactant and water molecules changes, So that the oil phase is evenly adsorbed on the microcapsule seeds;

(5) adding an initiator to heat up to initiate polymerization, so that the oil phase adsorbed on the surface of the inner liquid crystal microcapsules undergoes a polymerization reaction, and a phase separation process is initiated to prepare a polymer-coated dye-doped liquid crystal-coated polymer-coated dye. Multilayer structure dye-doped liquid crystal microcapsules of doped liquid crystal.

In an embodiment of the present invention, in the step (1), the mass fraction of the dichroic dye against the nematic liquid crystal is 0.1-6%.

In an embodiment of the present invention, in the step (2), the mass fraction of the soft monomer to the hard monomer is 50-200%, and the mass fraction of the crosslinking agent to the total amount of the soft and hard monomers is 10-50% , the mass fraction of organic monomers with low surface energy and high adhesion to the total amount of soft and hard monomers is 5-30%.

In an embodiment of the present invention, in the step (2), the dye-doped liquid crystal accounts for 1-15% of the total system mass fraction of the emulsion dispersion.

In an embodiment of the present invention, in the step (2), the content of the emulsifier in the emulsion dispersion is 10-50% to the mass fraction of the dye-doped liquid crystal.

In an embodiment of the present invention, in the step (2), the mass fraction of the mixed monomer to the dye-doped liquid crystal is 10-400%.

In an embodiment of the present invention, in the step (2), the mass fraction of the crosslinking agent to the total amount of soft and hard monomers is 10-50%.

In an embodiment of the present invention, the mass fraction of the organic monomer with low surface energy and high adhesion to the total amount of soft and hard monomers in the step (2) is 5-30%.

In one embodiment of the present invention, 0.1-15% of the initiator to the total amount of monomers is added dropwise during the coating reaction.

In one embodiment of the present invention, the initiator is one of potassium persulfate, ammonium persulfate, azobisisobutyl cyanide or azobisisobutylamidine hydrochloride.

In one embodiment of the present invention, the soft monomer includes ethyl acrylate, butyl acrylate, isooctyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, methyl acrylate One or both of n-octyl acrylate.

In an embodiment of the present invention, the soft monomer includes acrylates with chain lengths of 2-8 carbon atoms.

In one embodiment of the present invention, the hard monomers include styrene, methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, vinyl acetate, methyl vinyl ether , one or both of acrylonitrile, acrylamide, isoprene, and dicyclopentadiene.

In one embodiment of the present invention, the crosslinking monomer includes acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, divinyl acrylate One or both of benzene, ethylene glycol dimethacrylate, N-methylol acrylamide or diacetone acrylamide.

In an embodiment of the present invention, the organic monomers with low surface energy and high adhesion include trifluoroethyl methacrylate, trifluoroacetyl trifluoromethanesulfonate, 3-fluorophenyl acetate, One or both of dodecafluoroheptyl methacrylate, (perfluorohexyl) ethylene and hexafluorobutyl methacrylate.

In an embodiment of the present invention, the nematic liquid crystal comprises trans-butylcyclohexylcarboxylic acid, hydroxydiphenyl cyanide, 4-butylcyclohexylcarboxylic acid-4'-cyanobiphenolate, N-4-methoxy One or more of benzylidene-n-butylaniline, β-hydroxyethyl methacrylate (HEMA), and benzyl methacrylate (BMA).

In one embodiment of the present invention, the dyes include anthraquinone dyes, azo dyes or leek dyes.

In one embodiment of the present invention, the dyes include C.I. Disperse Yellow 119, C.I. Disperse Red 135, C.I. Disperse Red 343, C.I. Disperse Blue 79, C.I. Disperse Blue 165, C.I. Disperse Blue 257, C.I. Disperse Blue 148, C.I. Disperse Red 167 or C.I. Disperse Brown 1.

In one embodiment of the present invention, the emulsifier includes one of nonionic surfactants; the nonionic includes polyoxyethylene alkylphenol condensate: OP-7, OP-10 or OP-15, or polyoxyethylene fatty alcohol condensate: peregal O-10, peregal O-20, peregal O-25 or peregal A-20, or polyoxyethylene polyol ether fatty acid ester: Tween40, Tween60, Tween65 or Tween80; or polyoxyethylene esters of fatty acids: SG-10, SE-10 or OE-15;

In an embodiment of the present invention, the preparation method of the dye-doped liquid crystal in the step (1) is to first heat a certain proportion of the liquid crystal and the dichroic dye to dissolve completely, stir for 0.5-3 hours, and then cool down to the dyestuff. After the doped liquid crystal appears turbid, the temperature is heated until it is just transparent, and the mixture is stirred at a constant temperature for 0.5 to 5 hours to obtain the dye-doped liquid crystal.

In one embodiment of the present invention, the method specifically includes the following steps:

(1) Fully mixing a certain proportion of dichroic dye and nematic liquid crystal to prepare dye-doped liquid crystal, wherein the mass fraction of dye to liquid crystal is 0.1-6%, and dye-doped liquid crystal systems of different colors are prepared respectively;

(2) Under the action of mechanical stirring at a certain temperature, drop a dye-doped liquid crystal into an emulsifier aqueous solution at the same temperature to prepare a mixed system, wherein the dye-doped liquid crystal accounts for 1-15% of the total system mass fraction, The content of the emulsifier in the aqueous solution is 10-50% of the mass fraction of the dye-doped liquid crystal; the emulsion dispersion is prepared by high-speed emulsification, and the mixed monomer is added dropwise to the liquid crystal dispersion, and the emulsification is continued for 30 to 120 minutes, wherein the mixed monomer is mixed. The mass fraction of the dye-doped liquid crystal is 10-400%, the mass fraction of the soft monomer to the hard monomer in the mixed monomer is 50-200%, and the mass fraction of the crosslinking agent to the total amount of soft and hard monomers is 10-50 %, the mass fraction of organic monomers with low surface energy and high adhesion to the total amount of soft and hard monomers is 5-30%; then the emulsified dispersion is transferred to a four-necked flask with a condensation reflux and stirring device, After passing nitrogen for 5-30 minutes, under the stirring speed of 250-1000 r/min, the temperature was raised to 40-90 °C. After reaching the reaction temperature, 0.1-15% of the total monomer was added dropwise to the initiator, and the temperature was maintained. The reaction is carried out for 2 to 12 hours, and after the reaction is completed, the membrane is purified to obtain a dye-doped liquid crystal microcapsule emulsion with uniform particle size distribution;

(3) Add another mixed oil phase of dye-doped liquid crystal and monomer into the above dye-doped liquid crystal microcapsule emulsion, wherein the mass fraction of monomer to dye-doped liquid crystal is 10-400%, and the soft monomer in the monomer is 10-400%. The mass fraction of body to hard monomer is 50-200%. Adjust the rotation speed to 250-1000 rpm, and at the same time increase the temperature of the system to reach the cloud point of the non-ionic surfactant used, so that the binding force between the surfactant and water molecules becomes weaker, and the emulsification for 4-8h makes the oil phase evenly adsorbed in the inner layer surface of dye-doped liquid crystal microcapsules. Then slowly reduce the temperature of the system to room temperature, and at the same time reduce the rotation speed to 250-500 r/min, and keep emulsification for 0.5-2h; then transfer the emulsified dispersion to a four-necked flask with a condensation reflux and stirring device, and pass nitrogen through it. After 5 to 30 minutes, under the stirring speed of 250-500 r/min, the temperature is raised to 40 to 90 ° C. After reaching the reaction temperature, an initiator of 0.1-15% of the total monomer is added dropwise, and the reaction temperature is maintained for 2 ~12 hours; after centrifugal purification and drying, the desired multi-layer structure dye-doped liquid crystal microcapsules are obtained.

The second object of the present invention is to provide a dye-doped liquid crystal microcapsule using the above method.

The third object of the present invention is to provide a smart fiber, the preparation method of which is to use the above-mentioned dye-doped liquid crystal microcapsules.

The fourth object of the present invention is to apply the dye-doped liquid crystal microcapsules in the fields of flexible display technology and smart fibers.

Beneficial effects of the present invention:

In the multi-layer structure dye-doped liquid crystal microcapsule prepared by the method of the invention, the outer dye-doped liquid crystal and the polymer shell layer are used as the color developing layer and the core material dye-doped liquid crystal microcapsule is used for subtractive color matching, and at the same time As a protective layer, the inner layer dye-doped liquid crystal is protected from external environment pollution. The dyes employed in this method exhibit high order parameters, high dichroism and good solubility in host nematic liquid crystal matrix. The obtained liquid crystal microcapsules are not only bright and changeable in color and vivid in color rendering, which can meet people's requirements for personalization and diversity of clothing, but also the size of the liquid crystal microcapsules is 5-20 μm, the particle size is controllable, the particle size is uniform, and the liquid crystal microcapsules have good solvent resistance. High performance and water resistance, high core material loading, low driving voltage (lower than human body safe voltage), and can still maintain the original color performance after processing. And in application, the shell structure of the liquid crystal microcapsules can not only protect the liquid crystal, but also participate in film formation, and has good film formation, which is more suitable for coating requirements. The liquid crystal microcapsules prepared by the method of the invention have significantly improved display performance, better stability, better physical, chemical and optical properties and broad application prospects.

Description of drawings

Fig. 1 TEM image of dye-doped liquid crystal microcapsules;

Figure 2 is a polarizing microscope image of dye-doped liquid crystal microcapsules;

Figure 3 is a transmission electron microscope image of a multi-layer structure dye-doped liquid crystal microcapsule;

Figure 4 is a polarized light microscope image of a dye-doped liquid crystal microcapsule with a layered structure;

The transmission electron microscope picture of the microcapsule product prepared in Fig. 5 comparative example 1;

Figure 6 is a transmission electron microscope image of the microcapsule product prepared in Comparative Example 2.

Detailed ways

In order to be able to understand the technical content of the present invention more clearly, the following examples are given to illustrate in detail, the purpose of which is only to better understand the content of the present invention and not to limit the protection scope of the present invention.

Photoelectric performance test:

The prepared multi-layer dye-doped liquid crystal microcapsule emulsion is coated on a rigid substrate with electrodes. After the coating is completely dried, another rigid electrode is placed on the film, and the upper and lower electrodes are adhered with colloid. Combined, an encapsulation process is performed to obtain a rigid liquid crystal microcapsule display device. The liquid crystal microcapsule devices were driven by a DC steady-state voltage, respectively, to verify the electrochromic phenomenon of the display devices. The display effect and electro-optic performance of the liquid crystal microcapsule device were characterized respectively: the display effect of the device under voltage driving was recorded by real-time photography; the optical fiber spectrometer was used, and the central reflection wavelength of the device in the color developing state was used as the fixed detection wavelength. Incident light transmittance curves of the device under different applied voltages. During the test, the double-layer electrode was used as a blank reference.

Water/Solvent Resistance Test:

The water resistance test method and solvent resistance test method refer to GB/T 5211.5-2008, and the selected solvents include ethanol, ethylene glycol and acetone.

Example 1

Mix 0.01g of C.I. disperse red 60 and 1g of mixed liquid crystal E7 and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the red dye-doped liquid crystal was obtained.

The obtained red dye-doped liquid crystal was kept at the clearing point temperature, and it was added dropwise to an aqueous solution containing 0.2 g of lauryl alcohol polyoxyethylene ether at the same temperature under the action of mechanical stirring, and emulsified at high speed to form a uniform dispersion. ; Add 0.5g butyl methacrylate and 0.5g isoprene, 0.1g divinylbenzene and 0.05g trifluoroethyl methacrylate to the liquid crystal dispersion dropwise after uniform mixing, and continue to emulsify for 60 minutes . Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 5 minutes, under the stirring speed of 500 rev/min, heat up to 60 ° C, add 10 g of an aqueous solution containing 0.001 g of ammonium persulfate dropwise, and react After 2 hours, after returning to room temperature, the dye-doped liquid crystal microcapsule emulsion is obtained by repeated filtration and washing through the diaphragm. The dye-doped liquid crystal microcapsules have a particle size of 15 μm and show bright red at 25°C.

The prepared dye-doped liquid crystal microcapsules were observed by transmission electron microscope, and the photo of transmission electron microscope is shown in Figure 1. The above-prepared liquid crystal microcapsules with a core-shell structure were observed under a polarized light microscope, and the polarized light photo was shown in FIG. 2 .

Mix 0.01g of C.I. disperse blue 359 and 1g of mixed liquid crystal E7 and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the blue dye-doped liquid crystal was obtained.

The obtained blue dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to 0.5 g of hexyl acrylate and 0.5 g of methyl methacrylate at the same temperature under the action of mechanical stirring, and mixed uniformly to form a mixed solution. The latter oil phase was added dropwise to the dye-doped liquid crystal microcapsule emulsion prepared above. The temperature of the mixed system was raised to 90° C., and the mixture was emulsified for 5 hours at a stirring speed of 700 rpm. Subsequently, the temperature was lowered to room temperature, and the emulsification was continued for 0.5 h at a stirring speed of 400 rpm. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 5 minutes, under the stirring speed of 500 rev/min, heat up to 60 ° C, add 10 g of an aqueous solution containing 0.001 g of ammonium persulfate dropwise, and react After returning to room temperature for 6 hours, the membrane was filtered and washed repeatedly through a diaphragm to obtain a multi-layer structure dye-doped liquid crystal microcapsule emulsion. The multi-layer structure dye-doped liquid crystal microcapsules have a particle size of 20 μm and show purple color at 25°C.

The above-prepared liquid crystal microcapsules with a multi-layer structure were observed by transmission electron microscope, and the transmission electron microscope photograph was shown in FIG. 3 . The above-prepared liquid crystal microcapsules with a core-shell structure were observed under a polarized light microscope, and the polarized light photo was shown in FIG. 4 . It can be seen from FIG. 3 and FIG. 4 that the particle size of the core-shell structure liquid crystal microcapsules prepared by the above preparation method is uniform and controllable. The photoelectric performance test (see Table 1) and the water resistance and solvent resistance performance test (see Table 2) were carried out on the liquid crystal microcapsules with multi-layer structure prepared above.

Example 2

Mix 0.01g of C.I. disperse blue 359 and 1g of mixed liquid crystal E7 and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the blue dye-doped liquid crystal was obtained.

The obtained blue dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to an aqueous solution containing 0.1 g of OP-10 at the same temperature under the action of mechanical stirring, and emulsified at high speed to form a uniform dispersion; 0.5 g of hexyl methacrylate, 0.25 g of styrene, 0.375 g of divinylbenzene and 0.225 g of trifluoroacetyl trifluoromethanesulfonate were uniformly mixed and added dropwise to the liquid crystal dispersion, and emulsification was continued for 60 minutes. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 5 minutes, under the stirring speed of 500 rev/min, heat up to 60 ° C, add 10 g of an aqueous solution containing 0.001 g of ammonium persulfate dropwise, and react After 2 hours, after returning to room temperature, the dye-doped liquid crystal microcapsule emulsion is obtained by repeated filtration and washing through the diaphragm. The dye-doped liquid crystal microcapsules have a particle size of 15 μm and exhibit bright blue at 25°C.

Mix 0.01g of C.I. disperse red 60 and 1g of mixed liquid crystal E7 and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the red dye-doped liquid crystal was obtained.

The obtained red dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to 0.5 g of hexyl acrylate and 0.5 g of methyl methacrylate at the same temperature under the action of mechanical stirring, and the mixed liquid crystal was formed after uniform mixing. The oil phase was added dropwise to the dye-doped liquid crystal microcapsule emulsion prepared above. The temperature of the mixed system was raised to 80°C, and the mixture was emulsified for 5h at a stirring speed of 700 rpm. Subsequently, the temperature was lowered to room temperature, and the emulsification was continued for 2 h at a stirring speed of 400 rpm. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 5 minutes, under the stirring speed of 500 rev/min, heat up to 70 ° C, dropwise add 10 g of an aqueous solution containing 0.001 g of ammonium persulfate, react After returning to room temperature for 6 hours, the membrane was filtered and washed repeatedly through a diaphragm to obtain a multi-layer structure dye-doped liquid crystal microcapsule emulsion. The multi-layer structure dye-doped liquid crystal microcapsules have a particle size of 20 μm and show purple color at 25°C.

The photoelectric performance test (see Table 1) and the water resistance and solvent resistance performance test (see Table 2) were carried out on the liquid crystal microcapsules with multi-layer structure prepared above.

Example 3

Mix 0.001g of C.I. disperse blue 60 and 1g of mixed liquid crystal 5CB and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the blue dye-doped liquid crystal was obtained.

The obtained blue dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to an aqueous solution containing 0.5 g SE-10 at the same temperature under the action of mechanical stirring, and emulsified at high speed to form a uniform dispersion; 0.1 g of butyl acrylate, 0.2 g of methyl methacrylate, 0.003 g of diacetone acrylamide and 0.003 g of hexafluorobutyl methacrylate were uniformly mixed and added dropwise to the liquid crystal dispersion, and the emulsification was continued for 60 minutes. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 5 minutes, under the stirring speed of 1000 rpm, heat up to 70 ° C, dropwise add 10 g of an aqueous solution containing 0.045 azobisisobutyl cyanide , reacted for 2 hours, returned to room temperature, and repeatedly filtered and washed through a diaphragm to obtain a dye-doped liquid crystal microcapsule emulsion. The particle size of the dye-doped liquid crystal microcapsules is 8 μm, and it exhibits bright blue color at 25°C.

Mix 0.001g of C.I. disperse yellow 119 with 1g of mixed liquid crystal hydroxydiphenyl cyanide and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, and then heat up until it is just transparent. , stirring at constant temperature for 0.5h to obtain a yellow dye-doped liquid crystal.

The obtained yellow dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to 0.5 g of hexyl acrylate and 0.5 g of methyl methacrylate at the same temperature under the action of mechanical stirring, and the mixed liquid crystal was formed after uniform mixing. The oil phase was added dropwise to the dye-doped liquid crystal microcapsule emulsion prepared above. The temperature of the mixing system was raised to 95° C., and the mixture was emulsified for 4 h at a stirring speed of 700 rpm. Subsequently, the temperature was cooled to room temperature, and the emulsification was continued for 1 h at a stirring speed of 250 rpm. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 15 minutes, under the stirring speed of 500 rev/min, heat up to 60 ° C, dropwise add 10 g of an aqueous solution containing 0.001 g of ammonium persulfate, react After returning to room temperature for 8 hours, the membrane is filtered and washed repeatedly through a diaphragm to obtain a multi-layer structure dye-doped liquid crystal microcapsule emulsion. The multi-layer structure dye-doped liquid crystal microcapsules have a particle size of 15 μm and show green color at 25°C.

The photoelectric performance test (see Table 1) and the water resistance and solvent resistance performance test (see Table 2) were carried out on the liquid crystal microcapsules with multi-layer structure prepared above.

Example 4

Mix 0.05g of C.I. disperse yellow 119 and 1g of mixed liquid crystal 7CB and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the yellow dye-doped liquid crystal was obtained.

The obtained yellow dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to an aqueous solution containing 0.2 g of Tween 80 at the same temperature under the action of mechanical stirring, and emulsified at high speed to form a uniform dispersion; g hexyl acrylate and 0.05 g methyl acrylate, 0.002 g ethylene glycol dimethacrylate and 0.002 g (perfluorohexyl) ethylene are uniformly mixed and added dropwise to the liquid crystal dispersion, and emulsification is continued for 60 minutes. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 30 minutes, under the stirring speed of 1500 rev/min, heat up to 40 ° C, dropwise add 10 g of an aqueous solution containing 0.001 g of ammonium persulfate, react After 2 hours, after returning to room temperature, the dye-doped liquid crystal microcapsule emulsion is obtained by repeated filtration and washing through the diaphragm. The dye-doped liquid crystal microcapsules had a particle size of 3 μm and exhibited bright yellow at 25°C.

Mix 0.05g of C.I. disperse blue 60 and 1g of mixed liquid crystal 5CB and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the blue dye-doped liquid crystal was obtained.

The obtained blue dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to 2.0 g of hexyl acrylate and 2.0 g of methyl methacrylate at the same temperature under the action of mechanical stirring, and mixed uniformly to form a mixed solution. The latter oil phase was added dropwise to the dye-doped liquid crystal microcapsule emulsion prepared above. The temperature of the mixed system was raised to 80°C, and the mixture was emulsified for 8h at a stirring speed of 700 rpm. Subsequently, the temperature was lowered to room temperature, and the emulsification was continued for 0.5 h at a stirring speed of 400 rpm. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 30 minutes, under the stirring speed of 500 rev/min, heat up to 40 ° C, dropwise add 10 g of an aqueous solution containing 0.6 g of potassium persulfate, react After returning to room temperature for 12 hours, the membrane was filtered and washed repeatedly through a diaphragm to obtain a multi-layer structure dye-doped liquid crystal microcapsule emulsion. The multi-layer structure dye-doped liquid crystal microcapsules have a particle size of 5 μm and show green color at 25°C.

The photoelectric performance test (see Table 1) and the water resistance and solvent resistance performance test (see Table 2) were carried out on the liquid crystal microcapsules with multi-layer structure prepared above.

Table 1 Color properties of multi-layer structure dye-doped liquid crystal microcapsules

Table 2 Water resistance and solvent resistance of multi-layer structure dye-doped liquid crystal microcapsules

Comparative Example 1

Investigation of the effect of low surface energy monomers on the preparation of multilayer microcapsules:

Mix 0.01g of C.I. disperse red 60 and 1g of mixed liquid crystal E7 and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the red dye-doped liquid crystal was obtained.

The obtained red dye-doped liquid crystal was kept at the clearing point temperature, and it was added dropwise to an aqueous solution containing 0.2 g of lauryl alcohol polyoxyethylene ether at the same temperature under the action of mechanical stirring, and emulsified at high speed to form a uniform dispersion. ; Add 0.5 g of butyl methacrylate, 0.5 g of isoprene, and 0.1 g of divinyl benzene to the liquid crystal dispersion after uniform mixing, and continue to emulsify for 60 minutes. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 5 minutes, under the stirring speed of 500 rev/min, heat up to 60 ° C, add 10 g of an aqueous solution containing 0.001 g of ammonium persulfate dropwise, and react After 2 hours, after returning to room temperature, the dye-doped liquid crystal microcapsule emulsion is obtained by repeated filtration and washing through the diaphragm. The dye-doped liquid crystal microcapsules have a particle size of 15 μm and show bright red at 25°C.

Mix 0.01g of C.I. disperse blue 359 and 1g of mixed liquid crystal E7 and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the blue dye-doped liquid crystal was obtained.

The obtained blue dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to 0.5 g of hexyl acrylate and 0.5 g of methyl methacrylate at the same temperature under the action of mechanical stirring, and mixed uniformly to form a mixed solution. The latter oil phase was added dropwise to the dye-doped liquid crystal microcapsule emulsion prepared above. The temperature of the mixed system was raised to 90° C., and the mixture was emulsified for 5 hours at a stirring speed of 700 rpm. Subsequently, the temperature was lowered to room temperature, and the emulsification was continued for 0.5 h at a stirring speed of 400 rpm. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 5 minutes, under the stirring speed of 500 rev/min, heat up to 60 ° C, add 10 g of an aqueous solution containing 0.001 g of ammonium persulfate dropwise, and react After returning to room temperature for 6 hours, the membrane was filtered and washed repeatedly through a diaphragm to obtain a multi-layer structure dye-doped liquid crystal microcapsule emulsion.

The above-prepared liquid crystal microcapsules with a multi-layer structure were observed by transmission electron microscope, and the transmission electron microscope photograph was shown in FIG. 5 . Due to the lack of low surface energy monomers, even if the inner layer of microcapsules is constructed, the lipophilicity of the shell material is poor, so that the amount of adsorbed oil phase is small, and the desired multilayer liquid crystal microcapsule structure cannot be formed.

Comparative Example 2

Investigation of the effect of cross-linking monomers on the preparation of multilayer microcapsules:

Mix 0.05g of C.I. disperse yellow 119 and 1g of mixed liquid crystal 7CB and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the yellow dye-doped liquid crystal was obtained.

The obtained yellow dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to an aqueous solution containing 0.2 g of Tween 80 at the same temperature under the action of mechanical stirring, and emulsified at high speed to form a uniform dispersion; g hexyl acrylate, 0.05 g methyl acrylate and 0.002 g (perfluorohexyl) ethylene were uniformly mixed and added dropwise to the liquid crystal dispersion, and emulsification was continued for 60 minutes. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 30 minutes, under the stirring speed of 1500 rev/min, heat up to 40 ° C, dropwise add 10 g of an aqueous solution containing 0.001 g of ammonium persulfate, react After 2 hours, after returning to room temperature, the dye-doped liquid crystal microcapsule emulsion is obtained by repeated filtration and washing through the diaphragm. The particle size of the dye-doped liquid crystal microcapsules is 2 μm, and it exhibits bright yellow color at 25°C.

Mix 0.05g of C.I. disperse blue 60 and 1g of mixed liquid crystal 5CB and heat until it is just completely dissolved and becomes transparent. After stirring at this temperature for 0.5h, cool down until the mixture appears color or turbid, then heat up until it is just transparent, and stir at constant temperature. 0.5h, the blue dye-doped liquid crystal was obtained.

The obtained blue dye-doped liquid crystal was kept at the clearing point temperature, and was added dropwise to 2.0 g of hexyl acrylate and 2.0 g of methyl methacrylate at the same temperature under the action of mechanical stirring, and mixed uniformly to form a mixed solution. The latter oil phase was added dropwise to the dye-doped liquid crystal microcapsule emulsion prepared above. The temperature of the mixed system was raised to 80°C, and the mixture was emulsified for 8h at a stirring speed of 700 rpm. Subsequently, the temperature was lowered to room temperature, and the emulsification was continued for 0.5 h at a stirring speed of 400 rpm. Then transfer to a four-necked flask with condensation reflux and stirring device, pass nitrogen for 30 minutes, under the stirring speed of 500 rev/min, heat up to 40 ° C, dropwise add 10 g of an aqueous solution containing 0.6 g of potassium persulfate, react After returning to room temperature for 12 hours, the membrane was filtered and washed repeatedly through a diaphragm to obtain a multi-layer structure dye-doped liquid crystal microcapsule emulsion. The above-prepared liquid crystal microcapsules with a multi-layer structure were observed by transmission electron microscope, and the transmission electron microscope photograph was shown in FIG. 6 . Due to the lack of cross-linking agent, the shell material has low strength after the inner layer microcapsules are constructed, the swelling of the shell material by the organic solvent during the oil phase adsorption and the combined effect of the pressure of the outer layer polymer on the inner layer shell material during the phase separation process Under these conditions, the microcapsules are either ruptured or swollen and deformed, and a multi-layered microcapsule structure cannot be formed.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention should be defined by the claims.

Claims (10)

1. a preparation method of dye-doped liquid crystal microcapsules, is characterized in that, described method comprises: (1) fully mixing the dichroic dye and the nematic liquid crystal to prepare dye-doped liquid crystal materials with different color changes respectively; (2) Copolymerize a color dye-doped liquid crystal material with organic monomers, wherein the organic monomers include soft monomers, hard monomers, cross-linking monomers and organic monomers with low surface energy and high adhesion, and then Adding a surfactant to prepare a uniformly dispersed emulsion dispersion; the organic monomers with low surface energy and high adhesion include trifluoroethyl methacrylate, trifluoroacetyl trifluoromethanesulfonate, 3-fluorophenylethyl One or more of acid esters, dodecafluoroheptyl methacrylate, perfluorohexyl ethylene, and hexafluorobutyl methacrylate; (3) adding an initiator to initiate polymerization to obtain a liquid crystal microcapsule of a polymer-coated dye-doped liquid crystal material, and purifying the reacted emulsion to obtain a dye-doped liquid crystal microcapsule emulsion with uniform particle size distribution; (4) Using the dye-doped liquid crystal microcapsule emulsion prepared in the above (3) as a seed, another dye-doped liquid crystal material of different color is mixed with soft monomer and hard monomer to obtain an oil phase, which is added to the emulsion , so that the oil phase is evenly adsorbed on the microcapsule seeds; (5) adding an initiator to initiate polymerization, causing the oil phase adsorbed on the surface of the inner liquid crystal microcapsules to undergo a polymerization reaction, initiating a phase separation process, and preparing a polymer-coated dye-doped liquid crystal-coated polymer with a multi-layer structure Dye-doped liquid crystal microcapsules covering dye-doped liquid crystals; The soft monomer is one or both of ethyl acrylate, butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, n-octyl methacrylate and hexyl acrylate ; The hard monomers are styrene, methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, vinyl acetate, methyl vinyl ether, acrylonitrile, acrylamide, isopentyl One or both of diene and dicyclopentadiene. 2 . The method according to claim 1 , wherein the mass fraction of the cross-linking monomer to the total amount of soft and hard monomers is 10-50%. 3 . 3 . The method according to claim 1 , wherein the mass fraction of the organic monomer with low surface energy and high adhesion to the total amount of soft and hard monomers is 5-30%. 4 . 4 . The method according to claim 1 , wherein the mass fraction of the soft monomer to the hard monomer is 50-200%. 5 . 5. The method according to claim 1, characterized in that, in the step (2), the cross-linking monomer comprises acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, methacrylic acid, hydroxyethyl methacrylate, methyl methacrylate One or both of hydroxypropyl acrylate, divinylbenzene, ethylene glycol dimethacrylate, N-methylol acrylamide or diacetone acrylamide. 6 . The method according to claim 1 , wherein in the step (1), the mass fraction of the dichroic dye against the nematic liquid crystal is 0.1-6%. 7 . 7 . The method according to claim 1 , wherein in the step (2), the dye-doped liquid crystal accounts for 1-15% of the total system mass fraction of the emulsion dispersion. 8 . 8. The dye-doped liquid crystal microcapsules prepared by the method of any one of claims 1-5. 9 . A smart fiber, wherein the smart fiber is prepared by using the dye-doped liquid crystal microcapsules of claim 8 . 10. The application of the dye-doped liquid crystal microcapsules of claim 8 in the field of flexible display technology or smart textile.

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