KR102147599B1 - Photonic crystal structure and a method of fabricating the same - Google Patents

Abstract

The present invention relates to a photonic crystal structure and a manufacturing method thereof. The photonic crystal structure according to one embodiment of the present invention may include: a hydrophobic-hydrophilic block copolymer having a lamellar structure in which a hydrophobic polymer domain and a hydrophilic polymer domain are alternately repeated; a hydrogel material forming an interpenetrating polymer network (IPN) structure to which a hydrophilic polymer of the hydrophilic polymer domain is photo-crosslinked; and a transfer channel formed in the block copolymer in the thickness direction and transferring the hydrogel material to be photo-crosslinked to the hydrophilic polymer domain.

Description

Photonic crystal structure and a method of fabricating the same}

The present invention relates to a photonic crystal technology, and more particularly, to a photonic crystal structure and a method of manufacturing the same.

For the realization of an ultra-high-speed information society, the need for development of photoelectronic devices improved in terms of efficiency and integration is increasing, and therefore, interest in the use of photonic crystals that can control photons in a microscopic space. Is being concentrated. The photonic crystal is a material having a photonic band gap in which electromagnetic waves of a specific wavelength band are not transmitted by periodically changing the refractive index of the material, and includes optical filters, microlasers, electroluminescent devices, photovoltaic devices, optical switches, It has applicability to various optoelectronic devices such as sensors.

The method of manufacturing the photonic crystal is largely divided into two types. One is a top-down method based on nano-fine processing techniques such as lithography and ion beam etching, and the other is physical or chemical such as colloidal particles or polymers. It is a bottom-up method using self-assembly.

However, since the top-down method uses a fine processing technique, the process is complicated, expensive optical equipment is required, and a lot of cost is consumed. On the other hand, the bottom-up method has a problem in that it is difficult to control the colloidal particles, and there is a limitation in that only one stop-band can be expressed by one material, so it is possible to form a photonic crystal structure having various optical band gaps. In order to do so, there is an inconvenience of growing or generating a photonic crystal using a different colloidal solution or polymer each time.

In addition, since the bottom-up method using self-assembly uses a swelling agent to impart a structural color of a visible range, it is possible to express structural color mainly in a liquid state. For this reason, it may be difficult to change the microstructure of the photonic crystal by deteriorating the mechanical properties of the thin film having the photonic crystal, and it is difficult to simultaneously record and read the structural color.

Therefore, the technical problem to be solved by the present invention is that it is possible to easily express various optical band gaps at low cost, maintain mechanical properties, easily and sensitively change the microstructure of a photonic crystal, have reversibility, and have a fast reaction time. It is to provide a photonic crystal structure capable of being re-writable.

In addition, another technical problem to be solved by the present invention is to provide a method of manufacturing a photonic crystal structure having the above-described advantages.

According to an embodiment of the present invention, a hydrophobic-hydrophilic block copolymer having a lamellar structure in which a hydrophobic polymer domain and a hydrophilic polymer domain are alternately repeated; A hydrogel material forming an interpenetrating polymer network (IPN) structure in which the hydrophilic polymer of the hydrophilic polymer domain is photo-crosslinked; And a transfer channel formed in the block copolymer in the thickness direction and transferring the hydrogel material to be photo-crosslinked to the hydrophilic polymer domain may be provided. According to an embodiment, the wavelength of the initial reflected light of the photonic crystal structure is determined by the amount of the hydrogel material transferred to the hydrophilic polymer domain, and the amount of the hydrogel material is adjusted by the degree of the photocrosslinking. I can. As the amount of the hydrogel material increases or the degree of photocrosslinking between the hydrophilic polymer of the hydrophilic polymer domain and the hydrogel material increases, the initial reflected light may be red-shifted. The transfer channel is a topological defect of screw dislocation, and the hydrophobic-hydrophilic block copolymer may have a self-assembled structure. The photonic crystal structure is capable of inkjet printing using an ionic liquid, and the inkjet printed ionic liquid is first absorbed into the hydrophilic polymer domain having the IPN structure through the transfer channel, thereby locally expanding the hydrophilic polymer domain. By doing so, it is possible to implement full color. The ionic liquid first absorbed into the hydrophilic polymer domain is absorbed secondarily into the hydrogel block by a separate hydrogel block disposed on the hydrophobic-hydrophilic block copolymer, so that the photonic crystal structure can be initialized. . The hydrophobic polymer domain is any one or more of polystyrene, polycyclohexylethylene, and polymethylstyrene, and the hydrophilic polymer domain is polyvinylpyridine, polymethylmethacrylate, polybutylacrylate, polyethylene oxide, polylactide, and Any one or more of polyhydroxystyrene, and the hydrogel material is polyethylene glycol diacrylate (PEGDA), gelatin methacrylate (GelMA), acrylic acid, acrylamide, and N-isopropylacrylamide. It may be one selected from the group consisting of (N-isopropylacrylamide, NIPAAM), or a combination thereof. The photocrosslinking is performed by irradiation of any one of ultraviolet (Ultraviolet), infrared (infrared), visible ray, x-ray, gamma ray, and radio waves, and a photoinitiator (photo initiator) with the hydrogel material in the hydrophilic polymer domain initiator) and water (H2O).

According to another embodiment of the present invention, forming a hydrophobic-hydrophilic block copolymer layered structure having a structure in which a hydrophobic polymer domain and a hydrophilic polymer domain are alternately repeated and including a transport channel; And injecting a hydrogel material into the hydrophilic polymer domain through the transfer channel. And irradiating light so that the hydrophilic polymer of the hydrophilic polymer domain and the hydrogel material are crosslinked may be provided. In one embodiment, the step of forming the hydrophobic-hydrophilic block copolymerization layered structure comprises: preparing a block copolymer precursor solution; Spin coating the block copolymer precursor solution to form a block copolymer thin film; And it may include a step of solvent annealing the block copolymer thin film (solvent annealing). Injecting the hydrogel material into the hydrophilic polymer domain may include preparing a mixed solution containing the hydrogel material, a photo initiator, and water (H2O); It may include the step of coding the mixed solution on the hydrophobic-hydrophilic block copolymerized layered structure. The coating steps include dipping, spreading, brushing, knife coating, rolling, spraying, spin coating, and screen printing. And it may include a curtain coating (curtain coating).

According to another embodiment of the present invention, the step of preparing the photonic crystal structure according to claim 1; An information display method comprising the step of printing on the photonic crystal structure using ionic liquid ink may be provided.

According to an embodiment of the present invention, a hydrogel material to be photocrosslinked is delivered to the hydrogel material to be photocrosslinked by vertically penetrating a hydrophobic-hydrophilic block copolymer layered structure having an alternately repeated structure. By including a transport channel, it is possible to provide a photonic crystal structure capable of easily expressing various optical band gaps at low cost, having reversibility, and capable of re-writable having a fast reaction time.

According to another embodiment of the present invention, a method of manufacturing a photonic crystal structure having the above-described advantages can be provided.

1 is a cross-sectional view of a photonic crystal structure according to an embodiment of the present invention.
2 is a flowchart illustrating a method of manufacturing a photonic crystal structure according to an embodiment of the present invention, and FIGS. 3 and 4A to 4B are views for explaining a method of manufacturing a photonic crystal structure according to an embodiment of the present invention.
5A to 5C are TEM images showing a cross-sectional view of a photonic crystal structure according to an embodiment of the present invention, and FIGS. 6A to 6C are GISAXS for the photonic crystal structure of FIGS. 6A to 6C according to an embodiment of the present invention. Grazing-incidence small-angle scattering)
7A is a US-vis spectrophotometer experiment result for measuring the optical band value of the photonic crystal structure according to the UV exposure time, FIG. 7B is a graph showing the change of the stop band according to the UV exposure time, and FIG. 7C Is a color image expressed by the photonic crystal structure.
8 is a graph showing mechanical properties of a photonic crystal structure according to an embodiment of the present invention.
9 is a view for explaining a method of manufacturing a photonic crystal structure according to an embodiment of the present invention.
10A is a view showing a concept of inkjet printing on a photonic crystal structure according to an embodiment of the present invention, and FIG. 10B is an IPN printed with ionic liquid ink according to a change in concentration of the ionic liquid ink according to an embodiment of the present invention. A graph showing the UV-vis spectrum of a block copolymer having a structure, and FIG. 10C is a stop band position of a block copolymer having an IPN structure according to a change in concentration of an ionic liquid ink according to an embodiment of the present invention. 10D is an image of a photonic crystal structure of a self-assembled block copolymer (BCP) printed with an ionic liquid ink according to an embodiment of the present invention, and FIGS. 10E and 10F are This is an inkjet-printed image on a photonic crystal structure of a block copolymer having an IPN structure.
FIG. 11A is a diagram showing the repeated use of writing and erasing of a photonic crystal structure according to an embodiment of the present invention, and FIG. 11B is a diagram showing the repeated use of writing and erasing an ionic liquid ink and a hydrogel block according to an embodiment of the present invention. It is a diagram showing an image of the erased self-assembled block copolymer (BCP) photonic crystal structure, and FIG. 11C is a view of the self-assembled block copolymer (BCP) photonic crystal structure repeatedly written and erased using an ionic liquid ink and a hydrogel block. A diagram showing a UV-vis spectrum, FIG. 11D is a graph showing the position of a stop band of a self-assembled block copolymer (BCP) photonic crystal structure according to repetitive cycles of writing and erasing, and FIG. 11E is an ionic It is a UV-vis spectrum of a self-assembled block copolymer (BCP) photonic crystal structure in which liquid ink is gradually injected, FIGS. 11F to 11H are images of a photonic crystal structure, and FIG. 11I is a diagram showing color mixing.

The embodiments of the present invention are provided to explain the present invention more completely to those of ordinary skill in the art, and the following examples may be modified in various other forms, and the scope of the present invention is as follows. It is not limited to the examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete, and to completely convey the spirit of the present invention to those skilled in the art.

In addition, in the following drawings, the thickness or size of each layer is exaggerated for convenience and clarity of description, and the same reference numerals refer to the same elements in the drawings. As used herein, the term “and/or” includes any and all combinations of one or more of the corresponding listed items.

The terms used in this specification are used to describe specific embodiments, and are not intended to limit the present invention. As used herein, the singular form may include the plural form unless the context clearly indicates another case. Further, as used herein, "comprise" and/or "comprising" specifies the presence of the mentioned shapes, numbers, steps, actions, members, elements and/or groups thereof. And does not exclude the presence or addition of one or more other shapes, numbers, actions, members, elements, and/or groups.

Reference to a layer formed "on" a layer or another layer in this specification refers to a layer formed directly on the layer or other layer, or formed on an intermediate layer or intermediate layers formed on the layer or other layer. It may also refer to a layer. Further, for those skilled in the art, a structure or shape arranged “adjacent” to another shape may have a portion disposed below or overlapping with the adjacent shape.

In this specification, "below", "above", "upper", "lower", "horizontal" or "vertical" Relative terms such as, as shown on the drawings, may be used to describe the relationship between one component member, layer, or region with another component member, layer, or region. It is to be understood that these terms encompass not only the orientation indicated in the figures, but also other orientations of the device.

In the following, embodiments of the present invention will be described with reference to cross-sectional views schematically showing ideal embodiments (and intermediate structures) of the present invention. In these drawings, for example, the size and shape of the members may be exaggerated for convenience and clarity of description, and in actual implementation, variations of the illustrated shape may be expected. Accordingly, the embodiments of the present invention should not be construed as being limited to the specific shape of the region shown in this specification. In addition, reference numerals of members in the drawings refer to the same members throughout the drawings.

1 is a cross-sectional view of a photonic crystal structure according to an embodiment of the present invention.

Referring to FIG. 1, the photonic crystal structure 100 may include a block copolymer (BCP) including different polymer materials. In one embodiment, the block copolymer (BCP) may have a lamellar structure in which the hydrophilic polymer domain 10 and the hydrophobic polymer domain 20 are alternately repeated. The hydrophilic polymer domain 10 and the hydrophobic polymer domain 20 may refer to regions predominantly occupied by a hydrophilic polymer and a hydrophobic polymer, respectively. In one embodiment, the block copolymer (BCP) may have a self-assembled structure.

In one embodiment, the photonic crystal structure 100 is formed in the block copolymer (BCP) in a thickness direction, and a transfer channel 30 for transferring the hydrogel material 13 to be photocrosslinked to the hydrophilic polymer domain 10 It may include. The transfer channel 30 may be provided by a topological defect appearing in the photonic crystal structure 100 having a lamellar structure. The topological defect may be an edge dislocation, a screw dislocation, or a mixed dislocation. Preferably, in the present invention, the conveying channel 30 may be a helical dislocation.

As the hydrogel material 13 is transferred to the hydrophilic polymer domain 10 through the transport channel 30, the hydrophilic polymer of the hydrophilic polymer domain 10 and the hydrogel material 13 are photocrosslinked to each other, thereby interpenetrating the network ( Interpenetrating polymer network: IPN) structure can be formed. The IPN has properties of a crosslinked polymer having chemical resistance, solvent resistance, and heat resistance, and a synergistic effect of physical properties or a polymer blend of amphiphilicity because the network of the two crosslinked polymers is physically intertwined with each other. In addition, the morphology of the IPN can change the synthesis conditions (e.g., synthesis temperature, pressure, catalyst concentration, solvent, crosslinking density) during the synthesis process, and unlike polymer blends and block copolymers, the morphology formed once is between crosslinked structures. It can be maintained because of physical entanglement.

When the hydrogel material 13 is photo-crosslinked in the hydrophilic polymer domain 10, the reflected light in the visible light region can be maintained without swelling by a separate solvent, so that a solid photonic crystal structure can be formed without swelling of the liquid phase. When a photonic crystal is formed using a conventional block copolymer, if the hydrophilic polymer domain is not swelled in the solvent, it cannot have reflected light in the visible light region, or a high molecular weight block copolymer is self-assembled to form an in-plane lamellar structure. It can be difficult to form a photonic crystal because it has to.

In one embodiment, the hydrophilic polymer domain 10 may determine the wavelength of the initial reflected light of the photonic crystal structure 100 by the amount of the transferred hydrogel material 13, and the hydrophilic polymer domain 10 contains The amount of the gel material 13 may be controlled by the degree of photocrosslinking. Specifically, as the amount of the hydrogel material 13 increases or the degree of photocrosslinking between the hydrogel material 13 and the hydrophilic polymer of the hydrophilic polymer domain 10 increases, the initial reflected light of the photonic crystal structure 100 shifts red. It can be red-shifted and appear in the infrared region.

In one embodiment, the hydrophilic polymer domain 10 is a photoinitiator 12 and/or water (H2O) 11 in order to promote the photocrosslinking of the hydrophilic polymer of the hydrophilic polymer domain 10 and the hydrogel material 13 A photoinitiator and water may be mixed with the hydrogel material 13 and injected together through the transfer channel 30. Alternatively, the hydrogel material 13, the photoinitiator 12, and the water 11 may be sequentially injected through the transfer channel 30 randomly or in a random order.

In one embodiment, the photonic crystal structure 100 is a lamellar structure polystyrene (polystyrene)-polyvinylpyridine (poly(vinylpyridine)) copolymer, polystyrene-polymethylmethacrylate (poly(methylmethacrylate)) copolymer, polystyrene-poly (t-butylacrylate) (poly(tert-butylacrylate) copolymer, polyisoprene-poly(ethyleneoxide) copolymer, polystyrene-polylactide copolymer, polycyclo Hexylethylene (poly(cyclohexylethylene))-polylactide copolymer, or polymethylstyrene-polyhydroxystyrene copolymer may be used, but the present invention is not limited thereto. Any one or more of polymethylmethacrylate, poly(t-butylacrylate), poly(ethylene oxide), polylactide, and polyhydroxystyrene may be included in the hydrophilic polymer domain 10 in which the hydrophilic polymer is dominant, Any one or more of polystyrene, polyisoprene, polycyclohexylethylene, and polymethylstyrene may be included in the hydrophobic polymer domain 20 in which the hydrophobic polymer predominates.

In one embodiment, the hydrogel material 13 is polyethylene glycol diacrylate (PEGDA), gelatin methacrylate (GelMA), acrylic acid, acrylamide, and N-isopropylacrylamide (N- isopropylacrylamide, NIPAAM), or a mixture thereof.

The photoinitiator 12 may be selected from the group consisting of hydroxy ketone, benzophenone, acyl phosphine oxide, phenylglyoxylate, and mixtures thereof, and water 11 may be distilled water. However, the present invention is not limited to these materials.

The wavelength of the reflected light of the photonic crystal structure 100 according to an embodiment of the present invention is the amount of the hydrogel material 13 delivered to the hydrophilic polymer domain 10 and the hydrogel material 13 photocrosslinked with the hydrophilic polymer. ) Can be controlled by the degree of curing time.

The photocrosslinking may be performed by irradiation of any one of ultraviolet (UV), infrared, visible light, x-ray, gamma ray, and radio waves. Preferably, in the embodiment of the present invention, crosslinking may be performed by ultraviolet (UV) light.

In one embodiment, the photonic crystal structure 100 is capable of inkjet printing using an ionic liquid or water, and the inkjet printed ionic liquid is transferred to the hydrophilic polymer domain 10 having an IPN structure through the transfer channel 30. It is absorbed first and expands the hydrophilic polymer domain 10 locally, thereby realizing full color. The ionic liquid first absorbed into the hydrophilic polymer domain 10 is absorbed secondarily into the hydrogel block by a separate hydrogel block (not shown) disposed on the block copolymer (BCP), and photonic crystal The structure 100 is initialized and originally has initial reflected light.

In an embodiment, the initial reflected light (or first reflected light) of the photonic crystal structure 100 determined by the photocrosslinking appears as a first peak in the visible light region, and the ionic liquid or water is a hydrophilic polymer domain ( According to the additional injection to 10), the first peak may be red shifted to move to the infrared (IR) region. In addition, as the first peak is red shifted and moves to the infrared (IR) region, the second peak and the third peak, ..., n-th peak appear in the visible light region, and at this time, the photonic crystal structure 100 It may have a second reflected light.

In one embodiment, the ionic liquid is EMIBF4, EMITFSI, ethylmethylimidazolium chloride (EMIM Cl), ethylmethylimidazolium dicyanamide (EMIM DCA), ethylmethylimidazolium trifluoromethanesulfonate (EMIM Otf), ethylmethylimidazolium trifluoromethyl sulfonylimide (EMIM TFSI), ethylmethylimidazolium acetate (EMIM Ac), ethylmethylimidazolium hydrate (EMIM OH), ethylmethylimidazolium diethylphosphate (EMIM DEP), ethyl methyl imidazolium methyl carbonate (EMIM MeOCO2), ethyl methyl imidazolium lactate (EMIM Lactate), butyl methyl imidazolium chloride (BMIM Cl), butyl methyl imidazolium methyl carbonate solution (BMIM MeOCO2), butylmethylimidazolium trifluoromethanesulfonate (BMIM Otf), butylmethylimidazolium trifluoromethylsulfonylimide (EMIM TFSI), butylmethylimidazolium trifluoroacetate (BMIM CF3CO2) and dimethyl are It may be any one of midazolium methanesulfonate (MMIM CH3SO3).

A full color, rewritable reflection mode display can be provided based on a photonic crystal structure of a self-assembled block copolymer combined with inkjet printing. High-resolution full structure color images are printed by inkjet printing on the photonic crystal structure of solid one-dimensional self-assembled block copolymers in which ionic liquid ink is alternately composed of a lamellar structure containing IPN photo-crosslinked of a hydrogel polymer. can do. When the ionic liquid ink is sprayed onto the hydrophilic polymer domain 10 having the IPN structure, local expansion of the hydrophilic polymer domain 10 may occur, thereby forming various full-color structure color images. In addition, when a separate hydrogel block layer is disposed on the photonic crystal structure 100 of the self-assembled block copolymer, the ionic liquid may be completely removed from the photonic crystal structure 100 and initialized. Subsequently, by expressing the structural color again on the photonic crystal structure 100 through inkjet printing, a photonic crystal structure display of a flexible and rewritable self-assembled block copolymer suitable for various uses for storing and displaying nonvolatile information can be implemented.

In addition, in the present invention, the entire structure color in the range of B, G to R is changed in a small amount so that the effect of the ionic liquid ink with little volatility on the mechanical properties of the photonic crystal structure having the initial self-assembled block copolymer (BCP) is minimal. It is possible to easily and sensitively change the microstructure of the photonic crystal of the self-assembled block copolymer. It can also be utilized as a flexible and rewritable self-assembled block copolymer structure color inkjet display with simultaneous recording and structure color reading functions.

The photonic crystal structure 100 according to an embodiment of the present invention may be used in a printing apparatus such as an inkjet printing apparatus (not shown). The inkjet printing apparatus uses the photonic crystal structure 100 as an image output layer for outputting images or characters, and a mixture containing a hydrogel material 13 for determining a predetermined emission wavelength at a predetermined position, a photoinitiator, and water The solution may be printed on a desired position of the photonic crystal structure 100 using a nozzle of the inkjet printing device. In one embodiment, the photonic crystal structure 100 may be integrated with a substrate, and may be formed on a separate substrate.

The printed mixed solution may be absorbed by the hydrophilic polymer domain 10 to perform a binding reaction with a portion of the hydrophilic polymer, and the wavelength of light reflected from the photonic crystal structure 100 due to the binding reaction may be determined. In the mixed solution, the binding reaction may proceed only in some of the polymer domains of the hydrophilic polymer domain 10.

In one embodiment, the mixed solution may perform a binding reaction only with the hydrophilic polymer domain 10. The bonding reaction may be a cross-linking reaction, a covalent bonding, an ionic bonding or a hydrogen bonding, and preferably, a cross-linking or a covalent bonding.

2 is a flowchart illustrating a method of manufacturing a photonic crystal structure according to an embodiment of the present invention, and FIGS. 3 and 4A to 4B are views for explaining a method of manufacturing the photonic crystal structure.

2 and 3, the method of manufacturing a photonic crystal structure is a step of forming a hydrophobic-hydrophilic block copolymer layered structure having a structure in which a hydrophobic polymer domain and a hydrophilic polymer domain are alternately repeated and including a transport channel (S10). ; And injecting a hydrogel material into the hydrophilic polymer domain through the transfer channel (S20). And irradiating light so that the hydrophilic polymer of the hydrophilic polymer domain and the hydrogel material are crosslinked (S30).

The step of forming the hydrophobic-hydrophilic block copolymer layered structure (S10) includes first preparing a block copolymer precursor solution containing a hydrophilic polymer, a hydrophobic polymer, and a dispersion solvent, and using the block copolymer precursor solution into a block copolymer thin film It may include a step of spin-coating so as to be formed and a step of solvent annealing the block copolymer thin film. The hydrophilic polymer may be a polymer having a quaternized bonding group and pyridine in which carbon in a benzene ring is substituted with a nitrogen atom that is easy for hydrogen bonding, and the hydrophobic polymer may be polystyrene. Preferably, the hydrophilic polymer may be quaternized-poly-2-vinylpyridine (QP2VP), and the hydrophobic polymer may be polystyrene (PS).

The dispersion solvent is any of aliphatic or aromatic hydrocarbons (e.g., heptane, toluene), halogenated aliphatic, aromatic hydrocarbons (e.g., dichloromethane, bromobenzene), ether (e.g., diethyl ether), alcohol It may be one or a mixture thereof. Preferably, the dispersion solvent may be benzene, ethanol, or propylene glycol methyl ether acetate (PGMEA).

In one embodiment, the hydrophilic polymer and the hydrophobic polymer mixed in the dispersion solvent may be coated or printed on a substrate to form the block copolymer thin film. The coating or printing method may include spin coating, spray coating, dip coating, screen printing, inkjet printing, vacuum filtration, impregnation coating, coating coating, drop casting, or doctor blade. It could be the way.

It may be self-assembled by bonding by the hydrophilic polymer and the functional group included in the hydrophobic polymer. The self-assembled photonic crystal structure 100 may have a structure in which the hydrophilic polymer domain and the hydrophobic polymer domain are alternately repeated. The block copolymer is polystyrene-polyvinylpyridine copolymer, polystyrene-polymethylmethacrylate copolymer, polystyrene-poly(t-butylacrylate) copolymer, polyisoprene-poly(ethylene oxide) copolymer, polystyrene-poly It may be a lactide copolymer, a polycyclohexylethylene-polylactide copolymer, or a polymethylstyrene-polyhydroxystyrene copolymer. Preferably, the block copolymer may be a polystyrene-quaternized-polyvinylpyridine copolymer (PS-b-QP2VP).

The hydrophilic polymer and the hydrophobic polymer are alternately stacked in sequence, and a block copolymer having a lamella structure including a transport channel (eg, screw dislocation) may be formed, and then, annealing (annealing) ) Step may be selectively performed. The annealing step may be performed using a thermal annealing method or a solvent annealing method.

During the annealing process, the photonic crystal structure 100 may be formed in which the degree of repetition of the hydrophilic polymer and the hydrophobic polymer in the mixed solution is greatly improved. The repetitive alignment structure of the hydrophilic polymer domain and the hydrophobic polymer domain in the photonic crystal structure 100 is a lamellar structure, a cylinder structure, or a spherical structure according to the volume fraction of the hydrophilic polymer and the hydrophobic polymer contained in the photonic crystal structure 100 Can have Preferably, the hydrophilic polymer block and the hydrophobic polymer block in the photonic crystal structure 100 may have similar volume fractions, and accordingly, the hydrophilic polymer domain and the hydrophobic polymer domain in the photonic crystal structure 100 are lamellar. Can be arranged repeatedly into structures.

Referring to FIG. 4A, in an embodiment, in the step of selectively injecting a hydrogel material into the hydrophilic polymer domain (S20), a mixed solution including a hydrogel material, a photo initiator, and water (H2O) is prepared. And coding the mixed solution on the hydrophobic-hydrophilic block copolymerized layered structure. The coating steps include dipping, spreading, brushing, knife coating, rolling, spraying, spin coating, and screen printing. And it may be performed by any one of curtain coating (curtain coating). In this case, the hydrophilic polymer domains are swollen by water in the mixed solution, so that the photonic crystal structure may have a stop band characteristic corresponding to the first color.

In one embodiment, the hydrogel material is polyethylene glycol diacrylate (PEGDA), gelatin methacrylate (GelMA), acrylic acid, acrylamide, and N-isopropylacrylamide, NIPAAM) may be one selected from the group consisting of, or a mixture thereof. However, the present invention is not limited to these materials.

After step S30, a step of optionally drying the photonic crystal structure may be further included. Through the drying step, moisture injected by the hydrogel material may be removed, and thus the photonic crystal structure may be cured.

In one embodiment, in the step (S20) of selectively injecting a hydrogel material into the hydrophilic polymer domain, a part of the mixed solution is selectively injected into the hydrophilic polymer domain, and another part of the mixed solution is the hydrophobic- One block layer may be formed on the surface of the hydrophilic block copolymerized layered structure. Since the expansion ratios of the surface and the interior of the block layer are different, the block layer may be peeled from the hydrophobic-hydrophilic block copolymer layered structure by stress in the drying step.

4B, in an embodiment, after the hydrogel material (eg, PEGDA) is selectively injected into the hydrophilic-hydrophilic block copolymerization layered structure as a hydrophilic polymer domain (eg, P2VP), the hydrophobic-hydrophilic block copolymerization When the layered structure is exposed to ultraviolet rays (UV) (step S30), PEGDA and P2VP are cross-linked to form an interpenetrating polymer network (IPN) structure including PEGDA cross-linked in P2VP.

In an exemplary embodiment of the present invention, the hydrogel material, photoinitiator, which can change the wavelength of reflected light of the photonic crystal structure 100 by bonding with at least a portion of the photonic crystal structure 100 on the photonic crystal structure 100 A mixed solution containing photo initiator) and water (H2O) can be printed. The mixed solution may be selectively combined with any one domain of the photonic crystal structure 100.

In addition, the cross-link formed between the mixed solution and at least a portion of the hydrophilic polymer domain may be reversibly decomposed by printing a photonic crystal deletion material on the photonic crystal structure 100. In the photonic crystal structure according to an embodiment of the present invention, a reversible reaction is possible in which the cross-link of the photonic crystal material is formed and the cross-link is easily decomposed by the photonic crystal deletion material. Therefore, it is possible to display various images by using the photonic crystal structure 100 as a film.

The photonic crystal removal material may be hydrogen bromide, hydrochloric acid, hydrogen iodide, and preferably hydrogen bromide. The photonic crystal deletion material may selectively penetrate the hydrophilic polymer domain of the photonic crystal structure 100 during printing to decompose and delete the cross-link formed in the hydrophilic polymer domain. In this way, when the cross-link is decomposed, light of a predetermined wavelength that is generally reflected by the hydrophilic polymer domain may be output.

In this way, in the photonic crystal structure, cross-links between the hydrophilic polymers can be rapidly formed by the mixed solution in the hydrophilic polymer domain, and the cross-links can be reversibly decomposed by the photonic crystal deletion material. Therefore, the photonic crystal structure according to an embodiment of the present invention can be repeatedly used to generate various lights.

5A to 5C are TEM images showing a cross-sectional view of a photonic crystal structure according to an embodiment of the present invention, and FIGS. 6A to 6C are GISAXS for the photonic crystal structure of FIGS. 5A to 5C according to an embodiment of the present invention. Grazing-incidence small-angle scattering) is a graph showing the results. 5A is a cross-sectional view of a photonic crystal structure having an IPN structure emitting red color, FIG. 5B is a cross-sectional view of a photonic crystal structure having an IPN structure emitting green color, and FIG. 5A is a cross-sectional view of a photonic crystal structure having an IPN structure emitting blue color. to be.

5A to 5C, the photonic crystal structure is determined by the amount of the hydrogel material 13 and the degree of curing of the hydrogel material 13 photo-crosslinked with the hydrophilic polymer, depending on the wavelength of the reflected light (e.g., red, green, blue). Color). In addition, the reflected light of the photonic crystal structure can be further controlled by implanting ionic liquid or water.

Referring to FIG. 6A, it can be seen that the photonic crystal of the IPN structure emitting red color in the transmittance mode is well formed in the plane. Referring to FIG. 6B, the photonic crystal of the IPN structure emitting green color in the transmittance mode is in the plane. It can be seen that the photonic crystals of the IPN structure emitting blue color in the transmittance mode were well formed in the plane, referring to FIG. 6C.

The photonic crystal structure according to an embodiment of the present invention may reflect wavelengths having various optical band gaps. 7A to 7C show results of a US-vis spectrophotometer for measuring the optical band value of the photonic crystal structure according to the UV exposure time and color images represented by the photonic crystal structure.

7A and 7B, the reflection wavelength values of the photonic crystal structure when the hydrogel material is selectively injected into the hydrophilic polymer domain and exposed to ultraviolet rays for 10 sec, 20 sec, 30 sec, 40 sec, and 60 sec, respectively. As a result of comparison, it can be seen that as the exposure time increases, the maximum reflected wavelength value increases.

In one embodiment, when exposed to UV for 10 sec, the wavelength is about 455 nm, when exposed to UV for 20 sec, the wavelength is about 510 nm, and when exposed to UV for 40 sec, the wavelength is about 545 nm, When exposed to ultraviolet rays for 60 sec, the wavelength is about 560 nm, and as the exposure time to ultraviolet rays increases, it converges to about 570 nm and reflects visible light in the red region.

8 is a graph showing mechanical properties of a photonic crystal structure according to an embodiment of the present invention.

Referring to FIG. 8, the effective physical properties of the self-assembled block copolymer (BCP) photonic crystal structure having an IPN structure having an initial structural color of red, green, and blue, respectively, have a range of 300-500 MPa. IPN structure self-assembled block copolymer (BCP) with ionic liquid absorbed after ionic liquid ink is printed on the photonic crystal structure The effective properties of the photonic crystal structure (IPN+IL) are the IPN structure self-assembled block copolymer (BCP). ) It appears similar to the photonic crystal structure (IPN structure). Unlike other hydrogel-based photonic crystals, even if a color change occurs in the visible region, the mechanical strength is well maintained, which is generally much better than PEGDA-based photonic crystals in the kPa range. With such excellent mechanical properties, a self-assembled block copolymer (BCP) photonic crystal structure having an IPN structure can be applied to a semiconductor display.

9 is a view for explaining a method of manufacturing a photonic crystal structure according to an embodiment of the present invention.

Referring to FIG. 9, a PS-b-P2VP thin film having a thickness of approximately 700 nm constituting the PS and P2VP lamellar structural domains which are alternately aligned in a plane is spin-coated from propylene glycol monomethyl acetate (PGMEA) on a glass substrate. ), then the PS-b-P2VP thin film was prepared by performing solvent-annealing using chloroform vapor at 60° C. for 24 hours to form aligned one-dimensional photonic crystals. Next, the P2VP layer may be quaternized for 24 hours using a 1-bromoethane/hexane solution solution. After the thin film is dried, the PEGDA/DI/2-Hydroxy-2methylpropiophenone (HOMPP)/triton-X solution is drop-cast on the surface of the PS-b-P2VP thin film and absorbed into the quaternized P2VP domain of the thin film (PEGDA injection). ). The absorbed PEGDA oligomer is then UV cured with an ultraviolet lamp. Thereafter, optionally, the cured PEGDA oligomer on the surface of the PS-b-P2VP thin film is removed (removal of top PEGDA), and the surface or the whole of the PS-b-P2VP thin film is washed with water and then dried. I can make it. In the quaternized P2VP domain of the photonic crystal structure of PS-b-P2VP, PEGDA chains and P2VP chains are photocrosslinked to form an interpenetrating polymer network (IPN) structure.

10A is a view showing a concept of inkjet printing on a photonic crystal structure according to an embodiment of the present invention.

Referring to FIG. 10A, inkjet printing is the most useful and commonly used printing technique for printing full color information on paper, and IPN structure self-assembled block copolymer (BCP) photonic crystal structures disposed on glass Inkjet printing that can pattern full color information without any additional process is possible.

10B is a graph showing the UV-vis spectrum of a block copolymer having an IPN structure printed with an ionic liquid ink according to a change in the concentration of the ionic liquid ink according to an embodiment of the present invention, and FIG. 10C is an implementation of the present invention. It is a graph showing the position of a stop band of a block copolymer having an IPN structure according to a change in concentration of an ionic liquid ink according to an example. In one example, the photonic crystal structure of the block copolymer having the initial IPN structure before printing with the ionic liquid ink may have 250 nm of the visible light region as the maximum reflected light. Various times of UV exposure to a hydrogel material such as PEGDA can be used to change the initial structure color while maintaining the expanded state of the QP2VP domain of the photonic crystal structure. By locally spraying the ionic liquid ink on the photonic crystal structure, the QP2VP domain can be locally expanded.

10B and 10C, the degree of local expansion by ionic liquid ink is determined according to the concentration of the ionic liquid ink, and as the concentration of the ionic liquid ink increases, the self-assembled block copolymer ( It can be seen that the wavelength of the maximum reflection of the photonic crystal structure of BCP) is shifted in red.

10D is an image of a photonic crystal structure of a self-assembled block copolymer (BCP) printed with an ionic liquid ink according to an embodiment of the present invention.

Referring to FIG. 10D, it is shown that the structure color reflected according to the concentration of the ionic liquid ink can be conveniently controlled through a wide wavelength range from the near infrared region (NIR) to the visible ray region to the infrared region.

10E and 10F are images of inkjet printing on the photonic crystal structure of the block copolymer having an IPN structure according to an embodiment of the present invention. FIG. 10E is a photonic crystal structure of an IPN structured self-assembled block copolymer (BCP) on a Si wafer, and FIG. 10F is a photonic crystal structure of an IPN structured self-assembled block copolymer (BCP) transferred to a substrate such as paper. .

Referring to FIG. 10E, the photonic crystal structure of the self-assembled block copolymer (BCP) having an IPN structure has a blue color due to glass reflection of the Si wafer. 10F, the IPN structure self-assembled block copolymer (BCP) photonic crystal structure is easily separated from the substrate when immersed in a hydrogen bromide solution, and the photonic crystal structure of the self-assembled block copolymer (BCP) having an IPN structure is other It can be moved to the substrate. A metal-like reflection was observed in the IPN-structured self-assembled block copolymer (BCP) photonic crystal structure against the black background of the paper. As described above, by patterning and outputting the ionic liquid ink on the surface of the photonic crystal structure having the block copolymer having the IPN structure, various shapes such as characters, figures, or images can be expressed as structural colors.

The photonic crystal structure of the self-assembled block copolymer (BCP) printed with an ionic liquid ink such as EMITFSI can maintain the domain size up to at least 140°C, indicating that the EMITFSI-printed PEG-QP2VP domain is stable at temperature. . Note that the photonic crystal structure of the self-assembled block copolymer (BCP) having an IPN structure printed with the ionic liquid is thermally stable. Since the IPN-structured solid photonic crystal structure has already been expanded by the hydrogel material, a very small amount of ionic liquid ink can be used by inkjet printing to reflect the visible range of incident light. Since most ionic liquids are sensitive to humidity and hygroscopicity, ionic liquids such as EMIM + TFSI- which have little affinity with water molecules and less influenced by moisture are suitable for inkjet printing.

11A is a diagram showing repeated use of writing and erasing of a photonic crystal structure according to an embodiment of the present invention.

Referring to FIG. 11A, the ionic liquid ink is adjusted to the concentration of EMITFSI, ethyl alcohol (EtOH), and DI to have a resolution similar to that of a conventional inkjet printer. The information printed on the photonic crystal structure using the ionic liquid ink is non-volatile, local, and can have full color. If desired, the information printed with EMITFSI ink can be erased by contacting the fully expanded PEGDA hydrogel block with the surface of the photonic crystal structure. The ion concentration gradient between the P2VP domain of the photonic crystal structure and the PEGDA hydrogel block can transfer EMITFSI ions to the PEGDA hydrogel block. After drying the photonic crystal structure, the information is removed and ready to be reused. In order to control the wettability and mobility of the ink in the self-assembled block copolymer (BCP) photonic crystal structure having an IPN structure, the viscosity and contact angle of the ink may be adjusted by appropriately mixing ethanol, water, and an ionic liquid. Using fine-tuned EMITFSI inks, you can get images of almost the same resolution with conventional inkjet printers and RGB full color images. The structure color of the printed image may vary depending on the amount of EMITFSI droplets deposited on the surface of the self-assembled block copolymer (BCP) photonic crystal structure having an IPN structure.

Compared to the conventional multi-ink cartridge-based inkjet printing, the photonic crystal structure having the IPN structure of the present invention can form all RGB patterns with a single ionic liquid-based ink having a black/gray/white contrast. One of the drawbacks of conventional commercial inkjet printing is that once printed, paper cannot be reused. On the other hand, the IPN-structured self-assembled block copolymer (BCP) photonic crystal structure can be repeatedly recorded and deleted because ionic liquid molecules can be rearranged due to the gradient of ion concentration. By applying a UV-cured PEGDA hydrogel block, the water molecules of the hydrogel diffuse into the PEG-QP2VP domain through the screw potential of the IPN structure self-assembled block copolymer (BCP) photonic crystal structure, and the ionic liquid at this time due to the difference in ion concentration. It can be absorbed into the hydrogel block. Accordingly, since reversible writing and erasing are possible repeatedly, a self-assembled block copolymer (BCP) photonic crystal structure of an IPN structure having a maximum reflectance can be used for printing information display.

11B is a view showing an image of a self-assembled block copolymer (BCP) photonic crystal structure repeatedly written and erased using an ionic liquid ink and a hydrogel block according to an embodiment of the present invention.

Referring to FIG. 11B, it can be seen that the printing and erasing process using the ionic liquid ink and the hydrogel block was successfully performed.

11C is a view showing a UV-vis spectrum of a self-assembled block copolymer (BCP) photonic crystal structure repeatedly written and erased using an ionic liquid ink and a hydrogel block, and FIG. 11D is a repetitive cycle of writing and erasing. It is a graph showing the position of a stop band of a self-assembled block copolymer (BCP) photonic crystal structure according to.

Referring to FIG. 11C, it shows the reflection peak of the photonic crystal structure in the printed and erased state that coincides with the initial cutoff band. Referring to FIG. 11D, it is determined that the maximum value of the reflectance has a slight change after a number of erasing processes. It appears to be due to residual ionic liquid in the structure.

11E is a UV-vis spectrum of a self-assembled block copolymer (BCP) photonic crystal structure in which an ionic liquid ink is gradually injected, FIGS. 11F to 11H are images of the photonic crystal structure, and FIG. 11I is a diagram showing color mixing. .

11E to 11H, when ionic liquid ink is injected into a self-assembled block copolymer (BCP) photonic crystal structure and expanded beyond the visible light region (group I) (group II, group III), higher order The cutoff band peak of appears. Addition and mixing of light composed of secondary (red) and tertiary (blue) peaks may have an ionic liquid-expanded IPN structured self-assembled block copolymer (BCP) photonic crystal structure having a magenta color. As such, if there are several peaks in the visible range of the cut-off band, it can be seen that excellent photonic crystal color mixing is possible with the controlled very asymmetric lamellar structure of the self-assembled block copolymer (BCP) photonic crystal structure of the IPN structure.

As described above, in the case of the photonic crystal of the IPN structure, due to the asymmetric structure of the PS layer and the P2VP + hydrogel IPN structure layer, the primary reflection peak is red-shifted from the visible light region to the infrared (IR) region. ) Is possible. As a result, the second, third, and fourth peaks may appear in the visible light region, and as the order increases, the gap between the peaks narrows. Therefore, color mixing in the visible light region with one thin film It is possible, and the higher the peak, the higher the reflectance of the photonic crystal can be produced.

As described above, in the present invention, not only the dielectric constant of the photonic crystal of the self-assembled block copolymer, but also the microstructure spontaneously formed during the formation of a thin film are subjected to various external and environmental forces such as electric, magnetic, thermal solvation and mechanical stimulation. However, it can be easily changed, allowing reversible change of the structural color according to external stimuli. In addition, especially when combined with conventional printing techniques such as inkjet and laser printing, the structural color of the self-assembled block copolymer is localized and printed on the surface, making it suitable for nonvolatile, rewritable and printable displays.

As described above, since the photonic crystal structure 100 according to an embodiment of the present invention can reversibly change displayable light, various optoelectronics such as optical filters, microlasers, electroluminescent devices, photovoltaic devices, optical switches, and sensors It has applicability to devices, and allows reversible display of various colors in various display devices such as e-books and digital picture frames, as well as color filters in reflective display devices, and anti-counterfeiting tags ( tag).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and that various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those who have knowledge.

100: photonic crystal structure
10: hydrophilic polymer domain
11: water
12: photoinitiator
13: hydrogel material
20: hydrophobic polymer domain
30: feed channel

Claims (13)

A hydrophobic-hydrophilic block copolymer having a lamellar structure in which a hydrophobic polymer domain and a hydrophilic polymer domain are alternately repeated;
A hydrogel material forming an interpenetrating polymer network (IPN) structure in which the hydrophilic polymer is photo-crosslinked in the hydrophilic polymer domain; And
A photonic crystal structure comprising a transport channel that includes a topological defect formed in the block copolymer and selectively transfers the hydrogel material to be photocrosslinked to the hydrophilic polymer domain.
A hydrophobic-hydrophilic block copolymer having a lamellar structure in which a hydrophobic polymer domain and a hydrophilic polymer domain are alternately repeated;
A hydrogel material forming an interpenetrating polymer network (IPN) structure in which the hydrophilic polymer is photo-crosslinked in the hydrophilic polymer domain (of); And
It includes a topological defect formed in the block copolymer, and includes a transport channel for selectively transferring the hydrogel material to be photocrosslinked to the hydrophilic polymer domain,
The wavelength of the initial reflected light of the photonic crystal structure is determined by the amount of the hydrogel material transferred to the hydrophilic polymer domain,
A photonic crystal structure in which the amount of the hydrogel material is controlled by the degree of photocrosslinking. The method of claim 2,
The photonic crystal structure in which the initial reflected light is red-shifted as the amount of the hydrogel material increases or the degree of photocrosslinking between the hydrophilic polymer of the hydrophilic polymer domain and the hydrogel material increases. The method of claim 1,
The topological defect is a screw dislocation,
The hydrophobic-hydrophilic block copolymer is a photonic crystal structure having a self-assembled structure. A hydrophobic-hydrophilic block copolymer having a lamellar structure in which a hydrophobic polymer domain and a hydrophilic polymer domain are alternately repeated;
A hydrogel material forming an interpenetrating polymer network (IPN) structure in which the hydrophilic polymer is photo-crosslinked in the hydrophilic polymer domain (of); And
It includes a topological defect formed in the block copolymer, and includes a transport channel for selectively transferring the hydrogel material to be photocrosslinked to the hydrophilic polymer domain,
The photonic crystal structure is capable of inkjet printing using an ionic liquid,
The inkjet-printed ionic liquid is first absorbed into the hydrophilic polymer domain having the IPN structure through the transfer channel and locally expands the hydrophilic polymer domain, thereby implementing full color.
The method of claim 5,
A photonic crystal structure in which the ionic liquid first absorbed into the hydrophilic polymer domain is absorbed secondarily into the hydrogel block by a separate hydrogel block disposed on the hydrophobic-hydrophilic block copolymer, and the photonic crystal structure is initialized. .
The method of claim 1
The hydrophobic polymer domain is at least one of polystyrene, polycyclohexylethylene, and polymethylstyrene,
The hydrophilic polymer domain is at least one of polyvinylpyridine, polymethyl methacrylate, polybutyl acrylate, polyethylene oxide, polylactide, and polyhydroxystyrene,
The hydrogel material is a group consisting of polyethylene glycol diacrylate (PEGDA), gelatin methacrylate (GelMA), acrylic acid, acrylamide and N-isopropylacrylamide (N-isopropylacrylamide, NIPAAM). Photonic crystal structure which is one type selected from or a combination thereof.
The method of claim 1,
The photocrosslinking is performed by irradiation of any one of ultraviolet (Ultraviolet: UV), infrared (infrared), visible light, x-ray, gamma ray, and radio waves,
A photonic crystal structure further comprising a photo initiator and water (H2O) together with the hydrogel material in the hydrophilic polymer domain.
Forming a hydrophobic-hydrophilic block copolymer layered structure having a topological defect and having a structure in which the hydrophobic polymer domain and the hydrophilic polymer domain are alternately repeated; And
Injecting a hydrogel material into the hydrophilic polymer domain through the topological defect and selectively transferring it to the hydrophilic polymer domain; And
A method for producing a photonic crystal structure comprising irradiating light to crosslink the hydrophilic polymer of the hydrophilic polymer domain and the hydrogel material.
Forming a hydrophobic-hydrophilic block copolymerized layered structure having a structure in which the hydrophobic polymer domain and the hydrophilic polymer domain are alternately repeated and having a topological defect; And
Injecting a hydrogel material into the hydrophilic polymer domain through the topological defect and selectively transferring it to the hydrophilic polymer domain; And
Including the step of irradiating light so that the hydrophilic polymer of the hydrophilic polymer domain and the hydrogel material are crosslinked,
The step of forming the hydrophobic-hydrophilic block copolymerization layered structure,
Preparing a block copolymer precursor solution;
Spin coating the block copolymer precursor solution to form a block copolymer thin film; And
A method of manufacturing a photonic crystal structure comprising the step of subjecting the block copolymer thin film to solvent annealing.
The method of claim 9,
Injecting a hydrogel material into the hydrophilic polymer domain,
Preparing a mixed solution containing the hydrogel material, a photo initiator, and water (H2O);
A method of manufacturing a photonic crystal structure comprising the step of coating the mixed solution on the hydrophobic-hydrophilic block copolymerized layered structure.
The method of claim 11,
The coating steps include dipping, spreading, brushing, knife coating, rolling, spraying, spin coating, and screen printing. And a curtain coating method of manufacturing a photonic crystal structure.
Preparing the photonic crystal structure according to claim 1;
And printing on the photonic crystal structure using ionic liquid ink.

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