CN117148617A - Cellulose cholesteric liquid crystal micro-bubble based on solvent extraction technology and preparation method thereof - Google Patents
Cellulose cholesteric liquid crystal micro-bubble based on solvent extraction technology and preparation method thereof Download PDFInfo
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- CN117148617A CN117148617A CN202310989463.4A CN202310989463A CN117148617A CN 117148617 A CN117148617 A CN 117148617A CN 202310989463 A CN202310989463 A CN 202310989463A CN 117148617 A CN117148617 A CN 117148617A
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- 229920002678 cellulose Polymers 0.000 title claims abstract description 85
- 239000001913 cellulose Substances 0.000 title claims abstract description 85
- 239000004986 Cholesteric liquid crystals (ChLC) Substances 0.000 title claims abstract description 75
- 238000000638 solvent extraction Methods 0.000 title claims abstract description 41
- 238000005516 engineering process Methods 0.000 title claims abstract description 28
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 239000003094 microcapsule Substances 0.000 claims abstract description 68
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 30
- 238000000034 method Methods 0.000 claims abstract description 29
- 239000000463 material Substances 0.000 claims abstract description 11
- 239000000243 solution Substances 0.000 claims description 45
- 239000007788 liquid Substances 0.000 claims description 42
- 239000006185 dispersion Substances 0.000 claims description 28
- 229920002153 Hydroxypropyl cellulose Polymers 0.000 claims description 24
- 239000001863 hydroxypropyl cellulose Substances 0.000 claims description 24
- 235000010977 hydroxypropyl cellulose Nutrition 0.000 claims description 24
- 239000000839 emulsion Substances 0.000 claims description 22
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- 230000009471 action Effects 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 239000004094 surface-active agent Substances 0.000 claims description 9
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 239000012530 fluid Substances 0.000 claims description 8
- 239000000178 monomer Substances 0.000 claims description 8
- 239000011258 core-shell material Substances 0.000 claims description 7
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 6
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 claims description 6
- 229920000642 polymer Polymers 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 5
- 239000002904 solvent Substances 0.000 claims description 5
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 4
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 4
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 4
- DAKWPKUUDNSNPN-UHFFFAOYSA-N Trimethylolpropane triacrylate Chemical compound C=CC(=O)OCC(CC)(COC(=O)C=C)COC(=O)C=C DAKWPKUUDNSNPN-UHFFFAOYSA-N 0.000 claims description 3
- 239000002159 nanocrystal Substances 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- GTELLNMUWNJXMQ-UHFFFAOYSA-N 2-ethyl-2-(hydroxymethyl)propane-1,3-diol;prop-2-enoic acid Chemical class OC(=O)C=C.OC(=O)C=C.OC(=O)C=C.CCC(CO)(CO)CO GTELLNMUWNJXMQ-UHFFFAOYSA-N 0.000 claims description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical class [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical class [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 6
- 230000000737 periodic effect Effects 0.000 abstract description 6
- 230000035699 permeability Effects 0.000 abstract description 4
- 239000002775 capsule Substances 0.000 abstract description 2
- 239000002861 polymer material Substances 0.000 abstract description 2
- 239000000725 suspension Substances 0.000 abstract 1
- 239000012071 phase Substances 0.000 description 66
- 239000000523 sample Substances 0.000 description 12
- 238000001723 curing Methods 0.000 description 10
- 239000008385 outer phase Substances 0.000 description 9
- 239000008384 inner phase Substances 0.000 description 8
- 238000004132 cross linking Methods 0.000 description 7
- 239000011521 glass Substances 0.000 description 7
- 230000001105 regulatory effect Effects 0.000 description 6
- 238000001338 self-assembly Methods 0.000 description 6
- -1 biochemistry Substances 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- 239000003292 glue Substances 0.000 description 5
- 239000004698 Polyethylene Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 239000003086 colorant Substances 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 229920000573 polyethylene Polymers 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000012466 permeate Substances 0.000 description 3
- 238000000016 photochemical curing Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
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- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229940096522 trimethylolpropane triacrylate Drugs 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000012864 cross contamination Methods 0.000 description 1
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- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000012377 drug delivery Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000007046 ethoxylation reaction Methods 0.000 description 1
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- 150000004676 glycans Chemical class 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000819 hypertonic solution Substances 0.000 description 1
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- 230000001678 irradiating effect Effects 0.000 description 1
- 239000004530 micro-emulsion Substances 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000004038 photonic crystal Substances 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
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- 238000012805 post-processing Methods 0.000 description 1
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- 239000012488 sample solution Substances 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 230000000638 stimulation Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/02—Making microcapsules or microballoons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D11/00—Solvent extraction
- B01D11/02—Solvent extraction of solids
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
- C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
- C09K19/38—Polymers
- C09K19/3804—Polymers with mesogenic groups in the main chain
- C09K19/3819—Polysaccharides or derivatives thereof
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
- C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
- C09K19/54—Additives having no specific mesophase characterised by their chemical composition
- C09K19/56—Aligning agents
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K9/00—Tenebrescent materials, i.e. materials for which the range of wavelengths for energy absorption is changed as a result of excitation by some form of energy
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1334—Constructional arrangements; Manufacturing methods based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
- G02F1/13718—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on a change of the texture state of a cholesteric liquid crystal
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2201/00—Foams characterised by the foaming process
- C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
- C08J2201/054—Precipitating the polymer by adding a non-solvent or a different solvent
- C08J2201/0545—Precipitating the polymer by adding a non-solvent or a different solvent from an aqueous solvent-based polymer composition
- C08J2201/0546—Precipitating the polymer by adding a non-solvent or a different solvent from an aqueous solvent-based polymer composition the non-solvent being organic
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2351/00—Characterised by the use of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
- C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
- C09K19/54—Additives having no specific mesophase characterised by their chemical composition
- C09K19/542—Macromolecular compounds
- C09K19/544—Macromolecular compounds as dispersing or encapsulating medium around the liquid crystal
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
- C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
- C09K2019/528—Surfactants
Abstract
The application relates to a cellulose cholesteric liquid crystal microbubble based on solvent extraction technology and a preparation method thereof, comprising the following steps: the micro-fluidic technology is utilized to construct the micro-capsule which takes cellulose water solution as the inner core, does not dissolve in water, can be photo-cured and has the function of selective permeability after curing, and takes the hard polymer material as the shell layer. And combining the space effect of the limited domain and a solvent extraction method to induce water loss in the capsule to generate micro-bubbles, and simultaneously, enabling cellulose molecules to self-assemble into cholesteric liquid crystal with a periodic structure, so as to finally prepare the cholesteric liquid crystal micro-bubbles with a transparent shell layer, a middle layer with the periodic structure and a bubble inner core structure. The micro bubbles can see bright structural color under the irradiation of white light, and can be suspended in water to keep the structural color stable. Compared with the prior art, the preparation method combines the microfluidic technology, the space confinement effect and the solvent extraction technology to prepare the novel cholesteric liquid crystal material, and has the advantages of stable color, suspension, simple preparation operation and the like.
Description
Technical Field
The application relates to the technical field of advanced materials, in particular to a cellulose cholesteric liquid crystal microbubble based on a solvent extraction technology and a preparation method thereof.
Background
Cholesteric liquid crystal is a one-dimensional photonic crystal with a periodic spiral structure, has unique optical characteristics due to the special spiral structure, presents different structural colors under naked eyes, can realize a color changing function under the stimulation of light, heat, electricity and the like, and has very wide application value in the fields of military use, civil use and the like. Cellulose is a polysaccharide that is widely available in nature and constitutes a variety of structural colors in the plant world. Some cellulose derivatives are focused on the characteristics of good biocompatibility, degradability, optical stability, reproducibility and the like because of being capable of self-assembling into cholesteric liquid crystal with a certain periodic structure under a certain concentration. Thus, studies of cellulose-based cholesteric liquid crystals have attracted extensive interest to students. However, because of the good water solubility of cellulose and its derivatives, the cholesteric liquid crystal materials produced by them generally cannot be stored independently in aqueous solutions, often in oily solvents for storage or require relatively cumbersome post-processing. In addition, cellulose and its derivatives self-assemble into cholesteric liquid crystals only at high concentrations, but the high concentrations make their dispersions strongly viscous and thus difficult to use in processing, which limits the application of cellulose liquid crystals. Therefore, a brand new preparation method of cellulose cholesteric liquid crystal still needs to be developed.
Microfluidic technology is a technology for precisely controlling fluid flow and reaction in micron-sized space, and is a field related to high interdisciplinary science. Droplet microfluidic is an important branch, and generally uses the shearing force and surface tension of fluid to generate monodisperse micro-nano upgrading volume micro-droplets. Each micro droplet can be used as a reaction compartment of a space limiting domain, so that cross contamination in the reaction process can be avoided and the control is easy. In addition, the size and the type combination of the liquid drops can be precisely controlled by adjusting the flow rate or other parameters of the microfluidic fluid, so that the method is a simple and easily-controlled technology and plays an important role in biomedical applications. More importantly, the liquid drop and the microsphere or microcapsule prepared by the liquid drop can be used as a limited space, and the complete reaction of the molecules and the self-assembly of the colloidal particles can be promoted by limiting the molecules, the colloidal particles and the like in a local space. The process is free from the interference of external environment and has extremely strong independence, so that the process is widely focused by students and has wide application in a plurality of fields.
Solvent extraction is one of the common means for separating or purifying compounds, and can extract the required substances from solid/liquid, and the device required by the method is simple and easy to operate, is suitable for the extraction and separation of ultra-trace substances, and is widely applicable to the fields of environment, biochemistry, medicine and the like.
However, at present, no technology for preparing cellulose cholesteric liquid crystal microbubbles by combining microfluidic control, confined space and solvent extraction is available.
Disclosure of Invention
The application aims to overcome the defects of the prior art and provide a cellulose cholesteric liquid crystal microbubble based on a solvent extraction technology and a preparation method thereof, in particular to a technology for preparing the cellulose cholesteric liquid crystal microbubble by combining microfluidic, confined space and solvent extraction, which combines the advantages of the microfluidic, confined space and solvent extraction technologies and has the advantages of simple preparation process, stronger independence, small interference, no need of complex equipment, low cost, controllable product properties and the like.
The aim of the application can be achieved by the following technical scheme:
the first object of the present application is to provide a method for preparing cellulose cholesteric liquid crystal microbubbles based on solvent extraction technology, which prepares cellulose cholesteric liquid crystal microbubbles by combining microfluidic control, confined space and solvent extraction, the method comprising the following steps:
s1, preparing a cellulose water solution with a certain concentration (initial low concentration) as an internal phase;
s2, preparing a hard high polymer monomer solution containing a photoinitiator as an intermediate phase;
s3, selecting a surfactant aqueous solution as an external phase;
s4, injecting the internal phase obtained in the step S1, the intermediate phase obtained in the step S2 and the external phase fluid obtained in the step S3 into a double-emulsion microfluidic chip with a coaxial channel structure, breaking the internal phase and the intermediate phase fluid into liquid drops under the combined action of shearing force and surface tension between incompatible fluids, and wrapping the smaller liquid drops formed by the internal phase in the larger liquid drops formed by the intermediate phase, thereby obtaining double-emulsion liquid drops;
s5, under the irradiation of ultraviolet light, the outer layer of the double emulsion liquid drops is polymerized into solid, so that microcapsules of cellulose dispersion liquid with stable core-shell structures are obtained, and ultraviolet light curing is carried out again in a collecting bottle filled with an outer phase, so that microcapsules with hard shell layers are formed, and the microcapsules in the collecting bottle are obtained;
s6, washing the microcapsules in the collecting bottle obtained in the step S5 by using pure water, then placing the microcapsules in an extracting agent, extracting the microcapsules by using a solvent, continuously dehydrating the microcapsules under the action of the extracting agent, generating bubbles in the microcapsules, continuously increasing the concentration of the cellulose in the core along with the increase of the volume of the bubbles, and finally self-assembling the microcapsules into cholesteric liquid crystal with structural colors to obtain cellulose cholesteric liquid crystal microbubbles.
Further, the internal phase solution in S1 is a dispersion of an initial concentration (low concentration) of cellulose or cellulose derivative capable of self-assembling into a cholesteric liquid crystal having a bright structural color at a higher concentration range. Wherein the cellulose or derivative of cellulose may be one of cellulose nanocrystals, hydroxypropyl cellulose molecules, etc.; in order to enhance the self-assembly of the molecules at higher concentrations, some functional material molecules such as acrylamide, photoinitiators, cross-linking agents, and the like may also be added to the dispersion.
Further, the higher concentration is a concentration higher than that of the dispersion liquid of the initial concentration (low concentration).
Further, for cellulose derivatives such as cellulose nanocrystals and hydroxypropyl cellulose molecules, the concentration of self-assembled cholesteric liquid crystals is not the same, e.g., hydroxypropyl cellulose molecules self-assemble into cholesteric liquid crystals having bright structural colors in the concentration range of 50% -70%. Therefore, the initial concentration range of the cellulose and cellulose derivative dispersion is selected differently with respect to the internal phase solution.
Further, the mesophase solution in S2 is a water-insoluble, photocurable and hard polymer monomer solution containing a photoinitiator and having a selective permeability after curing, and a shell layer formed by photocuring the solution has a certain hardness and selective permeability, and can permeate through water molecules under the action of an extractant, but cannot permeate through chloride ions or sodium ions and the like, and an external extractant cannot reversely permeate into the shell layer. The hard high molecular monomer is one of ethoxylation trimethylolpropane triacrylate, trimethylolpropane triacrylate and the like; the concentration of photoinitiator is typically 1%.
Further, the external phase solution in S3 is an aqueous surfactant solution, such as one of polyvinyl alcohol (PVA), F108 or PVA-F108 combination solution.
Further, a coaxial microfluidic device or a capillary array microfluidic device is utilized to prepare double emulsion droplets, so that the microcapsule of the cellulose dispersion liquid with the stable core-shell structure is prepared.
Further, the extractant in S6 is one of ethanol, saturated sodium chloride, saturated potassium chloride and other solutions.
Further, in the solvent extraction process of the initial microcapsule in S6, microcapsules with different shell thicknesses have different reaction states under the action of the extractant.
Further, when the R/R range of the initial microcapsule in S6 is less than about a lower threshold (e.g., 0.8), the shell of the microcapsule is not significantly changed before the generation of bubbles by the extractant.
Further, when the R/R range of the initial microcapsule in S6 is greater than a certain higher threshold (e.g., 0.9), the cellulose dispersion microcapsule with a lower concentration will not generate bubbles, and the shell of the microcapsule will be in a collapsed state all the time, and finally forms a bowl shape and the like.
Further, the R/R range of the initial microcapsule in S6 is between the lower threshold and the upper threshold, and the cellulose dispersion microcapsule with lower concentration has a shell layer that is folded before generating bubbles, and the shell layer is restored when the bubbles are generated in the core.
Further, the cholesteric liquid crystal microbubbles prepared in S6 have stable structural color, suspendability and temperature sensitivity, when the cholesteric liquid crystal microbubbles are heated in a water bath, the structural color of the cholesteric liquid crystal can be obviously seen to be red shifted, and other functional material molecules such as propylene glycol, acrylamide, ethylene glycol and the like are mixed in the internal phase cellulose dispersion, so that the temperature sensitivity range of the prepared cholesteric liquid crystal can be enlarged.
Furthermore, the preparation method of the cellulose cholesteric liquid crystal micro-bubble needs to combine the three of micro-flow control, a limited space and solvent extraction, which is indispensable.
Furthermore, the number and color combination of the inner cores of the cholesteric liquid crystal microbubbles (cellulose cholesteric liquid crystal microbubbles) prepared by the method are controllable, and the initial concentration of different inner core compartments (inner cores of the microcapsules) is regulated, so that different color combinations can be obtained.
The second object of the present application is to provide a cellulose cholesteric liquid crystal micro-bubble based on solvent extraction technology, which is different from the traditional micro-capsule, the inner core has a bubble structure besides the wrapped cholesteric liquid crystal, and can be freely suspended in the liquid environment. In addition, the micro-bubble can see bright structural color under the irradiation of white light, has stable property and temperature-sensitive property, and can obviously see that the structural color of cholesteric liquid crystal is red shifted when being heated in water bath.
Compared with the prior art, the application has the following beneficial effects:
1) The preparation method of the cellulose cholesteric liquid crystal microbubble based on the solvent extraction technology is convenient to operate, easy to control, free of complex equipment and low in cost, and the main principle is that a finite field space is constructed based on the microfluidic technology, and cellulose self-assembly is induced by solvent extraction, so that the cellulose cholesteric liquid crystal microbubble with a core-shell structure is obtained.
2) The cellulose cholesteric liquid crystal micro-bubble based on the solvent extraction technology has structural color, can keep the stability of the structural color in aqueous solution, has a bubble structure, can suspend in the solution and sense the change of color caused by the change of the temperature of surrounding environment, and therefore has potential application value in the fields of underwater sensing, biomolecule detection and the like.
Drawings
Fig. 1 is a schematic diagram of an experiment for preparing a mononuclear-encapsulated low-concentration cellulose dispersion microcapsule by using a coaxial microfluidic device.
Fig. 2 is a schematic diagram of an experiment for preparing cellulose microcapsules with different concentrations by using a capillary array microfluidic device.
Fig. 3 is a schematic diagram of self-assembly of low-concentration cellulose microcapsules (microcapsules with core-shell structure after photo-curing of double emulsion droplets, that is, microcapsules with hard shell layer prepared in S5) into cholesteric liquid crystal microbubbles under the action of an extractant.
In the figure: 1. an internal phase conduit; 2. a mesophase conduit; 3. square tubes; 4. an outer phase conduit; 5. an inner tube seven-hole tube.
Detailed Description
The application will now be described in detail with reference to the drawings and specific examples. The following examples will assist those skilled in the art in further understanding the present application, but are not intended to limit the application in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present application.
In the technical scheme, the characteristics of preparation means, materials, structures or composition ratios and the like which are not explicitly described are regarded as common technical characteristics disclosed in the prior art.
From the perspective of the inventive concept, the microfluidic technology adopted in the technical scheme is a traditional double-emulsion microfluidic system, and double-emulsion is an emulsion nested system, can encapsulate and protect the excellent properties of some active materials, and has wide application in drug delivery, chemical reaction and separation. Double-emulsion microfluidics can generate microemulsion droplets by changing the track morphology of a microfluidic chip micro-pipeline and the flow characteristics of emulsion, and has fine regulation and control performances on the monodispersity of emulsion droplets and the size and the number of internal droplets, so that microcapsules with different morphologies and components are obtained. In addition, these microcapsules may constitute a confined space in which molecules, colloidal particles, etc. are enclosed and confined, promoting complete reaction of the molecules and self-assembly of the colloidal particles. The limited space formed by the inner core is not interfered by the external environment due to the core-shell structure of the microcapsule, and has extremely strong independence, so that the method has wide application in a plurality of fields. Solvent extraction is one of the common means for separating or purifying compounds, and has wide extraction solvent range, high selectivity and simple operation, and has wide application in the fields of materials, biochemistry, medicine and the like.
In summary, based on the above advantages, the application discloses a method for preparing novel cellulose cholesteric liquid crystal microbubbles by combining technologies such as microfluidic, confined space self-assembly, solvent extraction and the like. The application combines micro-flow control, limited space and solvent extraction to prepare micro-bubbles with bright structural color. The micro-bubbles are different from solid materials prepared by the traditional method and traditional microcapsules, have bubble structures inside and can be freely suspended in a liquid environment. The preparation method comprises the following steps: constructing a microcapsule which takes cellulose water solution as a core, does not dissolve in water, can be photo-cured and has a selective permeability function after curing and takes a hard polymer material as a shell layer by utilizing a micro-fluidic technology; and combining the space effect of the limited domain and a solvent extraction method to induce water loss in the capsule to generate micro-bubbles, and simultaneously, enabling hydroxypropyl cellulose molecules to self-assemble into cholesteric liquid crystal with a periodic structure, so as to finally prepare the cholesteric liquid crystal micro-bubbles with a transparent shell layer, a middle layer with the periodic structure and a bubble inner core structure. Under the irradiation of white light, the micro-bubbles can see bright structural color, and the micro-bubbles also keep the temperature-sensitive effect of the material based on the material characteristics of the inner core hydroxypropyl cellulose cholesteric liquid crystal because the bubble structure can be suspended in water and the property is stable.
The experimental methods used in the examples below, unless otherwise indicated, are conventional methods, and the reagents, methods and apparatus used, unless otherwise indicated, are conventional in the art.
(1) Constructing a microfluidic chip: the glass capillary is used for coaxially assembling and constructing a micro-fluidic chip (as shown in fig. 1, a single-core wrapped low-concentration cellulose dispersion microcapsule is prepared by using a coaxial micro-fluidic device, as shown in fig. 2, cellulose microcapsules with different concentrations are prepared by using a double-core wrapped cellulose microcapsule by using a capillary array micro-fluidic device), the inner, middle and outer three-phase channels are formed into axisymmetric arrangement through microscopic operation, and the axisymmetric arrangement is connected and fixedly assembled on a glass sheet by using a square tube 3.
(2) Preparing a sample solution: the aqueous cellulose dispersion with low concentration is used as an internal phase, a water-insoluble, photocurable and semi-permeable hard high-molecular monomer solution containing a photoinitiator is used as an intermediate phase, and an aqueous surfactant solution is used as an external phase.
(3) And a connecting device for adjusting the flow rate of each phase to prepare liquid drops.
(4) And (3) irradiating with ultraviolet light, curing and crosslinking to prepare the microcapsule.
(5) The microcapsule is collected and cleaned, and then is put into an extractant for solvent extraction, so as to prepare cholesteric liquid crystal microbubbles.
In the step (1), the coaxial microfluidic chip device comprises a glass slide, a capillary, a sample application needle head and quick-drying glue. The inner phase pipeline with the pipe caliber of 30-80 mu m is coaxially nested and inserted into the intermediate phase pipeline 2 with the pipe caliber of 120-180 mu m and the inner pore diameter of 580 mu m, and then the inner phase pipeline 1 and the intermediate phase pipeline 2 are coaxially nested and connected into the outer phase pipeline 4 with the inner pore diameter of 580 mu m through the square pipe 3. The sizes of the liquid drops and the microcapsules can be adjusted by changing the diameters of the pipe orifices of the internal phase pipe 1 and the intermediate phase pipe 2. The capillary array microfluidic device comprises a coaxial microfluidic device and a capillary array arranged in an internal phase pipeline, and as shown in fig. 2, the internal phase pipeline comprising the capillary array is an internal pipe seven-hole pipe 5.
In step (2), the internal phase solution is a low concentration aqueous cellulosic dispersion. The intermediate phase solution is a hard high polymer monomer solution which is insoluble in water, can be photo-cured and has a semi-permeability effect after being cured, and the outer phase solution is a surfactant aqueous solution. For example, the internal phase solution may be a dispersion of hydroxypropyl cellulose (HPC) at a concentration ranging from 10% to 28%, and the intermediate phase solution may be Ethoxylated Trimethylol Propane Triacrylate (ETPTA) with 1% photoinitiator added; the external phase solution may be a 2% F108 solution.
In the step (3), the three-phase solution inside, outside and inside in the injector is connected to the injection port of the inner phase and the outer phase of the device respectively through the polyethylene pipe, and the flow of the fluid in the channel of the device is controlled under the pushing of the external force of the mechanical pump.
In step (3), the size of the microcapsules and the number of cores can be controlled by controlling the proper liquid flow rate and the type of chip channels. For example, the typical internal phase flow rate can range from 10ul/h to 50ul/h; the flow rate of the intermediate phase ranges from 0.1ml/h to 1ml/h, the flow rate of the external phase ranges from 1ml/h to 5ml/h, and the common internal phase channels are single-hole capillaries (shown in figure 1) and seven-hole capillary arrays (shown in figure 2).
In the step (4), the initially prepared double emulsion droplets are subjected to initial photo-curing by ultraviolet irradiation in a collecting pipe (an external phase pipeline 4) of the chip so as to stabilize the core-shell distribution form of the microcapsules. Thereafter, the microcapsules fall into a collection bottle containing an external phase solution as a collection liquid and are irradiated again by an ultraviolet lamp, thereby being completely crosslinked and cured to form microcapsules having a hard shell layer.
In the step (5), water is used for cleaning.
In step (5), if absolute ethanol is used for solvent extraction, generally, bubbles will only appear when the microcapsules are immersed in absolute ethanol for more than 0.5 hours.
In step (5), the microcapsule (microcapsule with hard shell layer) prepared above and coated with the low-concentration cellulose dispersion is put into an extractant such as ethanol, and the inner core of the microcapsule gradually loses water under the action of the extractant, so as to generate bubbles. The hydroxypropyl cellulose molecules are well retained in the microcapsules due to the permselectivity of the shell layer (e.g., ETPTA). As the volume of bubbles in the core increases, the concentration of the dispersion liquid (e.g. hydroxypropyl cellulose) in the core increases, so that the dispersion liquid gradually self-assembles into cholesteric liquid crystal with structural color, and as the volume of bubbles increases, the pitch between cellulose rod-like molecules decreases gradually, so that the structural color of the cholesteric liquid crystal microbubbles shifts gradually blue (as shown in fig. 3). The final micro-bubble has bright and controllable structural color, and can be freely suspended in a liquid environment because the inner core of the micro-bubble contains a bubble structure.
Example 1
The mononuclear pure hydroxypropyl cellulose cholesteric liquid crystal micro-bubble is prepared by solvent extraction.
Pure hydroxypropyl cellulose cholesteric liquid crystal microbubbles are prepared according to the following method:
(1) Preparing an inner, middle and outer three-phase solution:
1.1 Internal phase solution): adding a certain amount of HPC into a proper amount of pure water to prepare HPC dispersion liquid with the concentration of 20-28 wt%, stirring for 48 hours by a stirrer, collecting, and preserving at normal temperature.
1.2 Mesophase solution: ETPTA dispersion containing 1% of photoinitiator by volume is preserved at normal temperature in a dark place.
1.3 External phase solution): an aqueous solution of surfactant F108 was prepared at a concentration of 2%.
(2) And constructing a chip device and a connecting device.
2.1 Building up chip devices): the single-hole capillary with the mouth diameter of the inner phase capillary (inner phase pipeline 1) being 30-80 mu m is coaxially nested in the capillary (middle phase pipeline 2) with the mouth diameter of the middle phase inner pipe being about 120-180 mu m, the front inner middle pipe group is coaxially nested in the outer capillary (outer phase pipeline 4) with the mouth diameter of the inner pipe being 580 mu m by utilizing a square pipe 3, and the single-hole capillary is fixed on a glass slide by quick-drying glue, and a point-like needle is fixed.
2.2 A) connection means: the three-phase solution of the inner, middle and outer phases are respectively filled into the injector, the injector is placed on a mechanical pump, and the injector is connected with the sample application needle head of the chip through a polyethylene tube.
(3) And regulating the flow rate to form liquid drops, and ultraviolet crosslinking and curing.
3.1 Adjusting the flow rate: the sample flow rate is adjusted to obtain single-core liquid drops with specific size. The value range of the flow velocity of the internal phase is 10ul/h to 50ul/h; the flow rate of the intermediate phase ranges from 0.1ml/h to 1ml/h, and the flow rate of the external phase ranges from 1ml/h to 5ml/h.
3.2 Drop formation, uv cross-linking curing: the double emulsion liquid drops are primarily irradiated by ultraviolet in an outer tube of the microfluidic chip, the morphology state of the double emulsion liquid drops is simply fixed, and then ultraviolet irradiation of the double emulsion liquid drops is carried out in a collecting bottle for further step, and complete solidification is carried out, so that the mononuclear microcapsule with good morphology is obtained.
(4) Placing into an extractant, and performing solvent extraction.
The microcapsules prepared above were put into absolute ethanol and observed under a microscope. The microcapsule can continuously lose water under the action of ethanol, the microcapsule with a thinner shell layer can generate sunken wrinkles before foaming, and the shell layer can not be restored until bubbles are generated in the inner core. The continuous water loss of the microcapsule enables the concentration of the HPC in the inner core to be continuously increased, cholesteric liquid crystal with bright structural color is self-assembled, the structural color of the cholesteric liquid crystal is continuously blue-shifted along with the continuous increase of the volume of the bubbles in the inner core, and the formed structural color can be observed by naked eyes under a microscope in a visible light range, so that cellulose cholesteric liquid crystal microbubbles are obtained.
Example 2
The binuclear pure hydroxypropyl cellulose cholesteric liquid crystal micro-bubbles with different combinations are prepared by solvent extraction.
(1) Preparing an inner, middle and outer three-phase solution, and extracting agent:
1.1 Internal phase solution): two different concentrations of aqueous HPC solutions (both in the range of 20wt% to 28 wt%) were prepared as in example 1.
1.2 Mesophase solution: ETPTA dispersion containing 1% of photoinitiator by volume is preserved at normal temperature in a dark place.
1.3 External phase solution): an aqueous solution of surfactant F108 was prepared at a concentration of 2%.
1.4 Extraction agent): absolute ethanol was chosen as hypertonic solution.
(2) And constructing a chip device and a connecting device.
2.1 Building up chip devices): drawing a seven-hole capillary array on a Bunsen burner, coaxially nesting an inner phase capillary tube orifice with the caliber of 10-30 mu m in a capillary tube with the caliber of about 150-280 mu m in an intermediate phase tube orifice, coaxially nesting a combination of an inner tube and an intermediate tube in an outer tube, connecting the three by using a square tube 3, fixing the three on a glass slide by using quick-drying glue, connecting a drawn specific capillary tube at a sample injection port at the other end of the seven-hole capillary tube (the seven-hole tube 5 of the inner tube), fixing the special capillary tube on the glass slide by using the quick-drying glue, and fixing a sample injection needle.
2.2 A) connection means: the three-phase solution of inner, middle and outer is respectively put into a syringe, the syringe is arranged on a mechanical pump, and the syringe is connected with a sample application needle head and a sample injection capillary of a chip by a polyethylene tube.
(3) And regulating the flow rate of the three phases of the inner phase, the middle phase and the outer phase to form liquid drops, and carrying out ultraviolet crosslinking and curing.
3.1 Adjusting the flow rate: and regulating the flow rate of the three phases to obtain the binuclear liquid drops with specific sizes and types. The current value of the internal phase is 5-30 ul/h, the current value of the intermediate phase is 0.1-0.3 ml/h, the current value of the external phase is 3-8 ml/h, and the sample outlet of the chip is directly inserted into the collecting bottle.
3.2 Drop formation, uv cross-linking curing: the formed double emulsion droplets with two component inner cores are irradiated by an ultraviolet lamp to be primarily solidified at the periphery of the inflow collecting outer tube, and fall into a collecting bottle filled with collecting liquid to be irradiated by ultraviolet again to be finally solidified.
(4) Extracting with solvent.
The binuclear cellulose dispersion microcapsules prepared as described above, having different initial concentrations of the cores, were put into absolute ethanol and observed under a microscope. The cellulose dispersion liquid binuclear with two different initial concentrations can simultaneously and continuously generate water loss, the concentration of the HPC in the inner core is continuously increased due to the continuous water loss of the microcapsule, and the cellulose dispersion liquid binuclear liquid crystal with bright structural color is self-assembled in the later period to obtain cellulose cholesteric liquid crystal microbubbles. As the initial concentration of the kernel is different, the final structural color combination is different along with the continuous increase of the volume of the kernel bubbles, and the color combination is usually red, red blue, red green, green blue, blue and the like.
Example 3
The mononuclear hydroxypropyl cellulose cholesteric liquid crystal micro-bubble with wider temperature sensitive range is prepared by solvent extraction.
(1) Preparing an inner, middle and outer three-phase solution:
1.1 Internal phase solution): adding a certain amount of HPC into a proper amount of pure water, and adding 10% of acrylamide relative to the mass ratio of HPC, wherein the final concentration of HPC is 20-28 wt%. Stirring for 48h by a stirrer, collecting, and preserving at normal temperature.
1.2 Mesophase solution: ETPTA dispersion containing 1% of photoinitiator by volume is preserved at normal temperature in a dark place.
1.3 External phase solution): an aqueous solution of surfactant PVA was prepared at a concentration of 10%.
(2) And (5) constructing a chip device and a connecting device.
2.1 A chip device is built: the single-hole capillary with the orifice diameter of the inner phase capillary being 30-80 mu m is coaxially nested in the capillary with the orifice diameter of the intermediate phase inner tube being about 120-180 mu m, the inner tube group is coaxially nested in the outer capillary with the orifice diameter of 580 mu m by utilizing the square tube 3, and the inner tube group is fixed on a glass slide by using quick-drying glue and is fixed with a spot sample needle.
2.2 A) connection means: the three-phase solution of the inner, middle and outer phases are respectively filled into the injector, the injector is placed on a mechanical pump, and the injector is connected with the sample application needle head of the chip through a polyethylene tube.
(3) And regulating the flow rate to form liquid drops, and ultraviolet crosslinking and curing.
3.1 Adjusting the sample flow rate: and regulating the flow rate of the sample to obtain single-core liquid drops with specific sizes. The value range of the flow velocity of the internal phase is 10ul/h to 50ul/h; the flow rate of the intermediate phase ranges from 0.1ml/h to 1ml/h, and the flow rate of the external phase ranges from 1ml/h to 5ml/h.
3.2 Drop formation, uv cross-linking curing: the double emulsion liquid drops are primarily irradiated by ultraviolet in an outer tube of the microfluidic chip, the morphology state of the double emulsion liquid drops is simply fixed, and then ultraviolet irradiation of the double emulsion liquid drops is carried out in a collecting bottle for further step, and complete solidification is carried out, so that the mononuclear microcapsule with good morphology is obtained.
(4) Placing into an extractant, and performing solvent extraction.
The microcapsules prepared above were put into absolute ethanol and observed under a microscope. The microcapsule continuously generates a water loss effect and generates bubbles under the action of ethanol, the concentration of the HPC of the inner core is continuously increased due to the continuous water loss of the microcapsule, the cholesteric liquid crystal with bright structural color is self-assembled in the later period, the structural color of the cholesteric liquid crystal is continuously blue-shifted along with the continuous increase of the volume of the inner core bubbles, and finally the cellulose cholesteric liquid crystal micro-bubbles with blue structural color are obtained.
(5) Water bath heating of cellulose cholesteric liquid crystal
The cellulose cholesteric liquid crystal micro-bubbles with blue structural color are heated in a water bath, and the structural color of the micro-bubbles gradually red shifts until becoming colorless along with the rise of the temperature. Which shows a range of variation in the water bath temperature of the structural color significantly greater than that of pure hydroxypropyl cellulose cholesteric liquid crystal microbubbles (example 1).
The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present application. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present application is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present application.
Claims (10)
1. The preparation method of the cellulose cholesteric liquid crystal micro-bubbles based on the solvent extraction technology is characterized by comprising the following steps:
s1, preparing an initial concentration cellulose aqueous solution as an internal phase;
s2, preparing a hard high polymer monomer solution containing a photoinitiator as an intermediate phase;
s3, selecting a surfactant aqueous solution as an external phase;
s4, injecting the internal phase obtained in the step S1, the intermediate phase obtained in the step S2 and the external phase fluid obtained in the step S3 into a double-emulsion microfluidic chip with a coaxial channel structure to obtain double-emulsion liquid drops;
s5, under the irradiation of ultraviolet light, the outer layer of the double emulsion liquid drops is polymerized into solid, so that a microcapsule of cellulose dispersion liquid with a stable core-shell structure is obtained, and ultraviolet light curing is carried out again in a collecting bottle, so that a microcapsule with a hard shell layer is formed;
s6, washing the microcapsule with the hard shell layer obtained in the step S5 by using pure water, then placing the microcapsule into an extractant, extracting the microcapsule by using a solvent, continuously dehydrating the microcapsule under the action of the extractant, generating bubbles in the microcapsule, continuously increasing the concentration of the cellulose in the core along with the increase of the volume of the bubbles, and finally self-assembling the microcapsule into the cholesteric liquid crystal with structural color, namely the cellulose cholesteric liquid crystal microbubbles.
2. The method of claim 1, wherein in step S1, the internal phase is an initial low concentration dispersion of cellulose or cellulose derivatives capable of self-assembling into a cholesteric liquid crystal having a bright structural color at a higher concentration range;
the cellulose or the derivative of the cellulose is one of cellulose nanocrystals and hydroxypropyl cellulose molecules.
3. The method for preparing cellulose cholesteric liquid crystal microbubbles based on solvent extraction technology according to claim 1, wherein the mesophase in step S2 is a water-insoluble, photocurable, and selectively permeable rigid polymer monomer solution containing a photoinitiator;
the hard high molecular monomer is one of ethoxylated trimethylolpropane triacrylate and trimethylolpropane triacrylate.
4. The method for preparing cellulose cholesteric liquid crystal microbubbles based on solvent extraction technology according to claim 1, wherein the external phase in step S3 is an aqueous surfactant solution;
the external phase is one of polyvinyl alcohol, F108 or PVA-F108 combination liquid.
5. The method for preparing cellulose cholesteric liquid crystal microbubbles based on the solvent extraction technique according to claim 1, wherein the extractant in step S6 is one of ethanol, saturated sodium chloride, and saturated potassium chloride solution.
6. The method for preparing cellulose cholesteric liquid crystal microbubbles based on the solvent extraction technique according to claim 1, wherein the microcapsules in step S6 have different reaction states under the action of the extractant in the solvent extraction process.
7. The method for preparing cellulose cholesteric liquid crystal microbubbles based on the solvent extraction technology according to claim 1, wherein the prepared cellulose cholesteric liquid crystal microbubbles in step S6 have stable structural color, suspendability and temperature-sensitive property, and the structural color of the cellulose cholesteric liquid crystal microbubbles is red-shifted when the cellulose cholesteric liquid crystal microbubbles are heated in a water bath; functional material molecules are mixed in the internal phase cellulose dispersion liquid, so that the temperature sensitive range of prepared cellulose cholesteric liquid crystal microbubbles can be enlarged; the functional material molecule comprises one of propylene glycol, acrylamide and ethylene glycol.
8. The method for preparing cellulose cholesteric liquid crystal microbubbles based on the solvent extraction technology according to claim 1, wherein the preparation method combines microfluidic control, confined space and solvent extraction.
9. The method for preparing cellulose cholesteric liquid crystal microbubbles based on the solvent extraction technology according to claim 1, wherein the number and color combination of the inner cores of the cellulose cholesteric liquid crystal microbubbles prepared by the method are controllable; by adjusting the initial concentration of the different kernel compartments, different color combinations are obtained.
10. Cellulose cholesteric liquid crystal microbubbles based on solvent extraction technique, obtained by a process according to any one of claims 1 to 9.
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