CN111045295A - Metal nanoparticle doped photopolymer compositions and gratings - Google Patents

Abstract

The present invention relates to a metal nanoparticle doped photopolymer composition and a grating, the photopolymer composition comprising: a writing monomer, a substrate, a photoinitiator system, and a noble metal precursor including an acid and/or salt of a noble metal.

Description

Metal nanoparticle doped photopolymer compositions and gratings

Technical Field

The invention belongs to the field of optical materials, and particularly relates to a photoinduced recording material composition, in particular to a metal nanoparticle doped photoinduced polymer.

Background

Augmented Reality (AR) is a new technology for superimposing real world information and virtual world information on the same picture or space in real time. Prompt information, virtual objects or virtual scenes are generated through a computer and are superposed in the real world to be perceived by human organs, so that the sense organ experience of augmented reality is achieved. AR technology is currently widely used in gaming, retail, educational, industrial, military, and medical fields.

At present, the augmented reality technology usually adopts a transmission-type optical display mode, in order to realize an optical transmission-type augmented reality display scheme, a traditional geometric optical system based on a semi-transparent and semi-reflective mirror or a free-form surface element is designed, and the superposition of virtual and real world is realized by utilizing refraction and reflection, however, the display system formed by the traditional optical element is limited by the total optical distance, cannot be light and thin enough and is far away from daily glasses; in addition, due to the constraint of lagrange invariants, the traditional optical display system has a limited exit pupil size and cannot be adapted to user groups with pupil distances at two ends. Waveguide-based display schemes effectively solve the above two problems compared to conventional optical systems. After a monochromatic or RGB image is projected into the waveguide, light is transmitted in the waveguide element through total reflection, so that the thickness of the optical element is effectively reduced; and simultaneously, one or more optical elements on the waveguide are used for controlling the image step output, so that the exit pupil expansion is realized.

Optical waveguides are divided into geometric optical waveguides and diffractive optical waveguides. The geometric optical waveguide is difficult to realize mass production due to the complex processing technology, and a mature glasses product does not exist. Currently, commercially available AR glasses such as HoloLens, Magic Leap, Digilens, and Akonia all use a diffraction light waveguide scheme. The technical scheme of the HoloLens and Magic Leap is that surface relief gratings are processed on a glass substrate by means of mature semiconductor processes such as photoetching, nanoimprint lithography and the like; the technical scheme of Digilens is to form a polymer with a periodically distributed refractive index through holographic exposure to obtain a holographic volume grating with a modulated refractive index. This polymer is a photopolymer. Holographic volume gratings are inexpensive to process and perform well in color compared to surface relief gratings, but the field of view (FOV) is also limited.

The FOV of a holographic grating depends on the degree of refractive index modulation (Δ n) of the photopolymer. The photopolymer composition consists essentially of a monomer, a matrix, and an initiator. It is generally believed that the Δ n of the photopolymer is determined by the difference in refractive index of the monomer and the matrix in the composition. The refractive index of the monomer is generally 1.50-1.65, the refractive index of the matrix is generally 1.45-1.52, the refractive index difference is 0.05-0.2, and the two are limited by phase separation. The surface relief grating is formed by periodically distributed polymer (the refractive index is 1.50-1.65) and air (the refractive index is 1), and the difference between the two is 0.50-0.65, which is far higher than that of the photoinduced polymer grating.

On the one hand, in theory, the refractive index modulation (Δ n) is improved by selecting the polymerizable components, especially the reactive monomers, in the photopolymer, although some progress has been made, the difficulty of selecting the material is large, and at the same time, the high refractive index monomers may also cause high production cost, and thus, the industrial mass production may have some difficulty.

In addition, the art has also attempted to improve the photopolymerized Δ n by Nanoparticle (NPs) doping. For example, reference 1 increases Δ n of the final grating from 0.003 to 0.022 (transmissive type) by doping high-refractive-index hyperbranched polymers (superbrachhedromers, refractive index 1.82) NPs. Similar studies have also been carried out with ZnS nanoparticle doping, POSS material doping, etc. However, since the high-refractive-index NPs doping not only increases the refractive index of the monomer region but also increases the refractive index of the matrix region, there is a limit to increase Δ n.

In recent years, researchers have also proposed increasing the Δ n of photopolymers by noble metal NPs doping. For example, citations 2 and 3 propose that Au nanoparticles can be doped in a photopolymer by using the localized surface plasmon resonance absorption effect of the Au nanoparticles, and after the monomer and the matrix are separated, the Au nanoparticles can form periodic distribution in addition to the periodic distribution of the refractive index, thereby forming an absorption grating for absorption modulation. The synergistic effect of the refractive index modulation and the absorption modulation provides possibility for further and greatly improving the delta n of the photopolymer.

Further, regardless of whether the previous organic NPs, inorganic semiconductor NPs, or noble metal NPs dope the photopolymer, the current method of doping by researchers is to directly add the NPs to the precursor of the photopolymer, and the dispersibility and phase separation of the NPs will be inhibited. Thus, there remains a need for improved methods and materials to increase the grating Δ n.

Cited documents:

cited document 1: omita, Y., et al, Nanoparticle-polymer composite porous composites dispersed with ultra-high-reactive-index hyperbranched polymers as organic nanoparticles, 2016.41(6): p.1281-1284.

Cited document 2: li, C., et al, logistic dynamics for mixed volume gradingsin gold nanoparticles attached photopolymers. optics Express,2014.22(5): p.5017-5028.

Cited document 3: li, C., et al, Hybrid polarization-angle multiplexing for volume hologrAN _ SNhy in gold nanoparticle-amplified photopolymers, optics Letters,2014.39(24): p.6891-6894.

Disclosure of Invention

Problems to be solved by the invention

In view of the above-mentioned problems, it is an object of the present invention to provide a nanoparticle-doped photopolymer composition which can improve the refractive index modulation of a grating formed of the nanoparticle-doped photopolymer by improving the doping method/characteristics of the nanoparticles.

Further, the invention also provides a grating based on a metal-doped, in particular noble metal-doped, photoactive composition and a process for its preparation.

Means for solving the problems

The inventor of the present invention has found through long-term research that the technical problems can be solved through implementation of the following technical scheme:

[1] the present invention first provides a photopolymer composition comprising:

the writing unit is a single body for writing,

a substrate, wherein the substrate is a glass substrate,

a photoinitiator system, and

a precursor of the noble metal is prepared,

the noble metal precursor includes an acid and/or a salt thereof of a noble metal.

[2] The composition according to [1], wherein the noble metal is selected from one or more of Ag, Au, Pt and Pd.

[3] The composition according to [1] or [2], further comprising a surfactant and/or an antioxidant in the precursor of the noble metal.

[4] The composition according to any one of [1] to [3], wherein the noble metal precursor is a solution containing an acid of the noble metal and/or a salt thereof, the solvent in the solution is selected from water or an organic solvent, and the concentration of the acid of the noble metal or the salt thereof in the solution is 0.1M to 10M in terms of the noble metal element.

[5] The composition according to any one of [1] to [4], wherein the writing monomer comprises an acrylate monomer and/or an epoxy compound having a refractive index of 1.50 or more.

[6] The composition according to any one of [1] to [5], wherein the content of the writing monomer is 30 to 60% by mass of the total composition; the content of the matrix is 20-50%; the content of the noble metal precursor is 0.01-5%.

[7] In addition, the present invention provides a diffraction grating comprising a resin film having a grating structure, the resin film being obtained by curing the composition according to any one of the above [1] to [6].

[8] Further, the present invention provides a method for producing the above diffraction grating, comprising the steps of:

a mixing step of mixing the components of the composition according to any one of the above [1] to [6] to obtain a mixture;

a step of forming a grating structure by forming a film of the mixture and forming a grating structure on at least a part of the film,

wherein the step of forming a grating structure includes a step of exposing the film with coherent light.

[9] The method according to [8], wherein the step of forming the grating structure comprises a step of compounding with the mixture using a spacer.

[10] The method according to [8] or [9], wherein the coherent light is derived from visible light.

[11] Furthermore, the present invention provides a holographic optical waveguide display element comprising the diffraction grating according to [7] or the diffraction grating obtained by the method according to any one of [8] to [10].

ADVANTAGEOUS EFFECTS OF INVENTION

Through the implementation of the technical scheme, the invention can obtain the following technical effects:

1) noble metal precursors, especially noble metal precursor solutions, are mixed with writing monomers, matrixes and other components, so that noble metal ions can be more easily and uniformly dispersed in the mixture;

2) by using the noble metal precursor, the nano metal particles can be formed in situ in the polymer cured product (grating) in association with the occurrence of the photoreduction reaction during the exposure.

3) By using the noble metal precursor, in the exposure process, in addition to the accumulation of the writing monomer to the bright area, the noble metal precursor can drive noble metal ions to migrate to the bright area, and the noble metal migrates in the form of ions, so that the migration is easier and more sufficient, and the improvement of the phase separation degree is facilitated;

4) the preparation method of the diffraction grating provided by the invention is simple and feasible, does not use expensive or toxic monomer substances, is easy for industrial large-scale production, and has strong controllability.

Drawings

FIG. 1: the photopolymerization process of the invention is schematically shown.

FIG. 2: the exposure light path in one particular embodiment of the present invention.

FIG. 3: comparative plot of diffraction efficiency for inventive examples versus comparative examples.

Detailed Description

The present invention will be described in detail below. The technical features described below are explained based on typical embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

in the present specification, the numerical range represented by "numerical value a to numerical value B" means a range including the end point numerical value A, B.

In the present specification, the numerical ranges indicated by "above" or "below" mean the numerical ranges including the numbers.

In this specification, the description will be made using "vicinity" to a certain wavelength of light, and it is understood that, for a specific wavelength, some error may occur from a theoretical value in use due to an instrument error or the like, and therefore, the use of "vicinity" indicates that various types of wavelengths defined in the present invention include an instrument error or the like.

In the present specification, the term "acrylate" includes the meanings of "acrylate" and "(meth) acrylate"; the term "acrylic" as used includes the meaning of "acrylic" as well as "(meth) acrylic".

In the present specification, "plural" in "plural", and the like means a numerical value of 2 or more unless otherwise specified.

In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

As used herein, the term "optional" or "optional" is used to indicate that certain substances, components, performance steps, application conditions, and the like are used or not used.

In the present specification, the unit names used are all international standard unit names, and the "%" used means weight or mass% content, if not specifically stated.

In the present specification, the term "particle diameter" as used herein means an "average particle diameter" unless otherwise specified, and can be measured by a commercial particle sizer.

In the present specification, reference to "some particular/preferred embodiments," "other particular/preferred embodiments," "embodiments," and the like, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.

< first aspect >

In a first aspect of the present invention, there is provided a photopolymer composition for a diffraction grating. The composition includes a writing monomer, a substrate, a photoinitiator system, and a noble metal precursor. Wherein an acid and/or salt of a noble metal contained in a noble metal precursor is dispersed in the composition, and metal atom nanoparticles having a periodic distribution of concentration are formed in situ in a cured product of the composition by means of a photochemical reduction reaction during photocuring.

Writing unit

The writing monomer suitable for the invention comprises acrylate monomers and/or epoxy compounds with the refractive index of more than 1.50.

In some preferred embodiments of the present invention, the writing monomer of the present invention has a refractive index of 1.52 or more, more preferably 1.55 or more, and even more preferably 1.57 or more, or 1.60 or more.

In the invention, the writing monomer and the matrix component (under the condition of coherent light irradiation) are mixed and exposed, so that the phase separation is generated in a bright area and a dark area, and further, the refractive indexes of the bright area and the dark area generate periodic difference, namely, the refractive index modulation degree delta n of the grating is generated. In some embodiments of the present invention, the writing monomer is polymerized/cured by gathering the writing monomer in the bright area through irradiation of coherent light, and after exposure, the bright area obtains a higher refractive index and the dark area has a relatively low refractive index, thereby providing the final grating with a higher refractive index modulation Δ n.

In some embodiments of the present invention, the writing monomer may include an acrylate monomer, an epoxy compound, or a mixture thereof. In some specific embodiments, the acrylate monomer and the epoxy compound may be used in any ratio, and preferably, the ratio of the acrylate monomer to the epoxy compound may be (90:10) to (10:90), and more preferably (70:30) to (30: 70). In other specific embodiments, such writing monomers include at least acrylate monomers.

The acrylic monomer used may be an acrylic monomer having an aromatic group. The invention considers that the aromatic group in the acrylate monomer is beneficial to improving the refractive index. In some preferred embodiments, the aromatic group is preferably one or more of phenyl, biphenyl, naphthyl, or fluorenyl.

In some specific embodiments, among the acrylate monomers, the acrylate monomer having an aromatic group may be selected from: biphenyl-containing acrylates such as [1, 1-biphenyl ] -4, 4-diylbis (2-methacrylate), 4' -biphenyldiacrylate and the like; naphthalene-containing acrylates such as 1-naphthalene methacrylate, 2 '-bis (2-acryloyloxy) -1, 1' -thiobinaphthalene, 2 '-bis [2- (2-acryloyloxyethoxy) -1, 1' -binaphthalene, 2 '-bis [ 2-acryloyloxyethoxy) -1, 1' -thiobinaphthalene and the like.

In addition to having an aromatic group, the halogen may optionally be substituted with a halogen including fluorine, chlorine or bromine, preferably bromine. Such acrylate monomers as p-chlorophenyl acrylate, p-bromophenyl acrylate, pentachlorophenyl acrylate, pentabromophenyl acrylate, 2,4, 6-tribromophenyl acrylate, 2,4, 6-trichlorophenyl acrylate and the like can be exemplified.

In addition, in some preferred embodiments of the present invention, the acrylate monomer suitable for use in the present invention may have a structure of the following general formula (I-1) or (I-2):

Ar-L-(X-O)_n-C(O)-CH＝C(R₁)₂(I-1)

Ar-L-(X-O)_n-C(O)-C(CH₃)＝C(R₁)₂(I-2)

wherein Ar represents a group having one or more aromatic groups, preferably having 1 to 3 benzene rings, more preferably a phenyl group, a naphthyl group or a biphenyl group, and optionally, these benzene rings may be substituted or unsubstituted; l represents an oxygen atom or sulfurAn atom; x represents a linear or branched alkyl group having 1 to 6 carbon atoms, preferably a linear or branched alkyl group having 2 to 3 carbon atoms, which may be optionally substituted; n represents an integer of 1 to 5, preferably an integer of 1 to 3; r₁Each occurrence, which is the same or different, independently represents a hydrogen or halogen atom including a fluorine atom, a chlorine atom or a bromine atom.

In addition to the acrylic monomers having one polymerizable group disclosed above, in some other preferred embodiments of the present invention, acrylic monomers having two functional groups may be used, and these monomers may have the following general formula (II-1) or (II-2):

wherein R is₁X, L is as defined in (I-1) and (I-2), n represents an integer of 1 to 5, preferably an integer of 1 to 3, Z represents a group containing one or more aromatic groups, preferably Z represents a substituted or unsubstituted phenyl or biphenyl group, the substitution may be of a halogen including fluorine, chlorine or bromine.

As a preferable mode for the respective embodiments, the acrylate monomer preferably used in the present invention may be selected from 9, 9-bis [4- (2-acryloyloxyethoxy) biphenyl ] fluorene, 9-bis [4- (2-hydroxy-3-acryloyloxypropyloxy) phenyl ] fluorene, 9-bis [4- (2-mercapto-3-acryloyloxypropyloxy) phenyl ] fluorene, [1, 1-biphenyl ] -4, 4-diylbis (2-methacrylate), 4 '-biphenyldiacrylate, 1-naphthalene methacrylate, 2' -bis (2-acryloyloxy) -1,1 '-thiobinaphthyl, 2' -bis [2- (2-acryloyloxyethoxy) -1, one or more of 1 ' -binaphthalene, 2 ' -bis [ 2-acryloyloxyethoxy) -1,1 ' -thiobinaphthalene, 2,4, 6-tribromophenyl acrylate and pentabromophenyl acrylate.

Further, as the epoxy compound monomer suitable for the present invention, those having a refractive index of 1.50 or more, preferably, 1.55 or more may be mentioned. The use of such epoxy compounds is advantageous for mitigating the effects of dimensional shrinkage in the fabrication of gratings.

In the present invention, the epoxy compound that can be used may have a structure of the following general formula (III):

wherein E represents an epoxy group-containing group. In some specific embodiments, each E group may contain 1 or 2 epoxy groups. Further, from the viewpoint of suppressing the dimensional shrinkage after film formation, in a preferred embodiment, each E group contains 1 epoxy group at the time of its occurrence.

The structure of the epoxy group is not particularly limited, and the epoxy group is preferably present as an aliphatic epoxy group. In other embodiments, the epoxy group or epoxy structure of the E group is bonded to Ar as described above through an ether group₁The groups are linked. The ether group may be a sulfide group or an oxygen ether group, and is preferably an oxygen ether group from the viewpoint of suppressing the dimensional shrinkage after film formation.

In the general formula (III), n representing the number of E groups is an integer of 0 to 4, and each E group is the same or different. It goes without saying that the total number of n in the present invention is not 0. In some preferred embodiments, each occurrence of n is 1.

In the above general formula (III), each Ar₁The same or different, independently represent an aryl-containing group. In some preferred embodiments of the invention, Ar₁Represents a group having 1 or two substituted or unsubstituted benzene rings, typically Ar₁May be selected from the following structures:

wherein X in the formula (b) is selected from a single bond, O or S atom.

In the above general formula (III), -CR₃R₄Can form a carbonyl group, or, R₃、R₄The same or different, each occurrence independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group or an aryl group having 6 to 30 carbon atoms, and R₃、R₄May be connected via a single bond; preferably an alkyl group, an alkoxy group or a phenyl group having 1 to 3 carbon atoms.

In some preferred embodiments of the present invention, the epoxy compound suitable for use in the present invention, for example, 9-bis (4-epoxypropyloxyphenyl) fluorene or has a structure represented by the following general formula (IV):

wherein R is₃And R₄Have the same definition as in formula (III).

R₅Each occurrence is the same or different and is independently selected from hydrogen, halogen and alkyl with 1-5 carbon atoms; preferably 1 to 3 alkyl groups, and x is 0 to 4, preferably an integer of 0 or 1. The halogen may be F, Cl or a Br atom.

In a further preferred embodiment, the epoxy compound suitable for use in the present invention has a structure represented by the following general formulae (IV-1) to (IV-3):

in the present invention, one kind of the epoxy compound may be used, or a mixture of two or more kinds of the epoxy compounds may be used.

The epoxy compounds suitable for use in the present invention can be obtained by a preparation method generally used in the art, and in a typical embodiment, can be carried out using a coupling reaction of epichlorohydrin with a phenolic compound:

in some preferred embodiments of the present invention, it is also advantageous to use an acrylate monomer having a plurality of (three or more) functional groups in addition to the acrylate monomer having a high refractive index and the epoxy compound monomer to increase the crosslinking density at the time of exposure/curing. Generally, such monomers may have a refractive index of 1.42 to 1.5. Further, such acrylate monomers may be exemplified by one or more of pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol penta/hexa-acrylate, and polyester acrylate oligomers.

In some embodiments of the present invention, the acrylate monomer having three or more functional groups is used in an amount of 50% or less, preferably 10 to 45%, and more preferably 20 to 40%, based on the total weight of the writing monomers.

In the present invention, the writing monomer may be used in an amount of 30 to 60%, preferably 35 to 55%, more preferably 40 to 50%, for example, 32%, 37%, 42%, 45%, 47%, 57% or the like, based on the total weight of the photopolymer composition of the present invention.

Other polymerizable Components

In the present invention, other optional polymerizable components may be used in the photopolymer composition in addition to the writing monomers described above without affecting the technical effects of the present invention.

These other optional polymerizable components may include other acrylate monomers and/or epoxy compounds than those described above.

In some specific embodiments, it is possible for these other acrylate monomers to include mono-and difunctional acrylates, mono-and difunctional urethane acrylates, specifically:

other acrylates that may be used are, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, ethoxyethyl acrylate, ethoxyethyl methacrylate, N-butyl acrylate, N-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, hexyl acrylate, hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, butoxyethyl acrylate, butoxyethyl methacrylate, dodecyl acrylate, dodecyl methacrylate, isobornyl acrylate, isobornyl methacrylate, phenyl acrylate, N-carbazole acrylate, and the like.

Other urethane acrylates which may be used are understood to mean compounds having at least one acrylate group which have at least one urethane bond. Such compounds are known to be obtainable by reacting hydroxy-functional acrylates with isocyanate-functional compounds.

For this purpose, isocyanate-functional compounds such as aromatic, araliphatic, aliphatic and cycloaliphatic diisocyanates can be used. Mixtures of such diisocyanates may also be used. Suitable di-, tri-or polyisocyanates are, for example, butylidene isocyanate, Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), 2, 4-and/or 2,4, 4-trimethylhexamethylene diisocyanate, bis (4,4' -isocyanatocyclohexyl) methane isomers and mixtures thereof having any desired isomer content, isocyanatomethyl-1, 8-octane diisocyanate, 1, 4-cyclohexyl diisocyanate, cyclohexanedimethylene diisocyanate isomers, 1, 4-phenylene diisocyanate, 2, 4-and/or 2, 6-toluene diisocyanate, 1, 5-naphthalene diisocyanate, 2,4' -or 4,4' -diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, m-methylthiophenyl isocyanate or derivatives thereof having a urethane, urea, carbodiimide, acylurea, isocyanurate, allophanate, biuret, oxadiazinetrione, uretdione or iminooxadiazinedione structure and mixtures thereof. Aromatic or araliphatic diisocyanates are preferred.

Hydroxy-functional acrylates or methacrylates suitable for preparing the abovementioned urethane acrylates are the following compounds: 2-hydroxyethyl (meth) acrylate, polyethylene oxide mono (meth) acrylate, polypropylene oxide mono (meth) acrylate, polyhexamethylene oxide mono (meth) acrylate, poly (. epsilon. -caprolactone) mono (meth) acrylate, for example

M100(Dow, Schwalbach, Germany), 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxy-2, 2-dimethylpropyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, hydroxy-functional mono-, di-or tetraacrylates of polyols such as trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, ethoxylated, propoxylated or alkoxylated trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol or industrial mixtures thereof. 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate and poly (. epsilon. -caprolactone) mono (meth) acrylate are preferred.

In other specific embodiments, for these other epoxy compounds, optionally, an epoxy compound having an aromatic ring may be used, and these other epoxy compounds have a certain refractive index. In some preferred embodiments, for example, having a refractive index of 1.45 or greater.

Further, there may be exemplified other epoxy compounds such as:

wherein Y represents a single bond or a heteroatom such as O or S.

These other polymerizable components are contained in an amount of 15% or less, preferably 10% or less, and more preferably 5% or less, based on the total weight of the photopolymer composition of the present invention.

Matrix composition

In the present invention, a matrix is used to provide low refractive index portions after phase separation. In general, writing monomers tend to migrate toward the bright areas when exposed to coherent light, thereby causing phase separation from the substrate in the dark areas.

In some particular embodiments of the invention, the matrix may be selected from film-forming components and/or low refractive index polymerizable monomers.

The film-forming component suitable for use in the present invention may be selected from polymers or resinous materials having a molecular weight of 1000 or more with some degree of adhesion. Preferably, these materials have a relatively low refractive index, and in some specific embodiments, the refractive index of these materials is 1.480 or less.

In the present invention, suitable film-forming components include:

homopolymers of vinyl acetate or copolymers of vinyl acetate with acrylates, ethylene, styrene, etc.;

cellulose esters such as cellulose acetate, cellulose acetate-butyrate;

cellulose ethers such as methyl cellulose, ethyl cellulose, and benzyl cellulose, and the like;

polyvinyl alcohol;

polyvinyl acetals such as polyvinyl butyral, polyvinyl formal and the like;

polyurethanes, typically obtained by reacting polyols such as polytetrahydrofuran, polyethylene glycol, polypropylene glycol, castor oil, polycaprolactone polyol, and the like, and isocyanates such as hexamethylene-1, 6-diisocyanate, 1, 4-cyclohexane diisocyanate, methyl-2, 4-diisocyanate, and the like;

styrene/butadiene-based block copolymers;

polyvinylpyrrolidone, and the like.

A preferred film-forming component of the present invention may be polyurethane from the viewpoint of improving the degree of modulation of the refractive index of the final grating.

In addition, as the polymerizable monomer to be used as a matrix in the present invention, preferably, a polymerizable monomer having a lower photopolymerization activity than the above writing monomer may be selected. Also, in some preferred embodiments of the present invention, these polymerizable monomers as the matrix have a refractive index of less than 1.50, preferably less than 1.48, and more preferably less than 1.45.

In some preferred embodiments, polymerizable monomers suitable for use in the present invention as the matrix may include fluoroacrylate monomers, and/or substituted or unsubstituted vinyl esters of fatty acids.

As the fluorine-containing acrylic ester monomer, one or more of C1 to C10 alkyl esters having fluorine-substituted acrylic acid, preferably one or more of C1 to C6 alkyl esters having fluorine-substituted acrylic acid, may be cited.

In some preferred embodiments, the fluorine-containing acrylate monomer may be an alkyl acrylate having a perfluoro substitution. Examples of such monomers are 1,1,1,3,3, 3-hexafluoroisopropyl acrylate (n ═ 1.319), octafluoropentyl acrylate (n ═ 1.349), 1H, 2H-perfluorooctanol acrylate (n ═ 1.338), 2,3,3, 3-pentafluoropropyl acrylate (n ═ 1.336), hexafluorobutyl methacrylate (n ═ 1.361), hexafluorobutyl acrylate (n ═ 1.352), 2,3,3,4,4, 4-heptafluoro-butyl methacrylate (n ═ 1.341), hexafluoroisopropyl methacrylate (n ═ 1.331) or heptafluorobutyl acrylate (n ═ 1.331).

For substituted or unsubstituted fatty acid vinyl esters, fatty acid vinyl ester monomers with or without halogen substitution can be used. In some specific embodiments, the number of carbon atoms of the fatty acid moiety is 2 to 25, preferably 4 to 17. Examples of such monomers include vinyl acetate (n ═ 1.395), vinyl propionate (n ═ 1.403), vinyl n-butyrate (n ═ 1.410), vinyl valerate (n ═ 1.417), vinyl n-hexanoate (n ═ 1.421), vinyl 2-ethylhexanoate (n ═ 1.426), vinyl octanoate (n ═ 1.429), vinyl neononanoate (n ═ 1.441), vinyl decanoate (n ═ 1.435), vinyl neodecanoate (n ═ 1.436), vinyl laurate (11C chain, n ═ 1.441), vinyl myristate (13C chain, n ═ 1.443-445), vinyl palmitate (15C chain) and vinyl stearate (17C chain, n ═ 1.442).

In the present invention, the content of each of the fluorine-containing acrylate monomer and the substituted or unsubstituted fatty acid vinyl ester in the polymerizable monomer as the matrix is not particularly limited, and in some specific embodiments, the content of the substituted or unsubstituted fatty acid vinyl ester is 50 to 65% by mass based on the total mass of the polymerizable monomer as the matrix.

In addition, for the present invention, it is advantageous to increase the degree of modulation of the refractive index of the final holographic recording material as the writing monomer described above has a higher refractive index and a larger difference in refractive index from the matrix component. Therefore, in some preferred embodiments of the present invention, the difference in refractive index between the acrylic monomer and/or the epoxy compound having a refractive index of 1.50 or more as the writing monomer and the matrix component is 0.070 or more, preferably 0.075 or more, and more preferably 0.078 or more.

In the present invention, the total amount of the matrix may be 20 to 50%, preferably 30 to 48%, more preferably 35 to 45%, for example, 25%, 32%, 40%, 42% or the like, based on the total weight of the photopolymer composition of the present invention.

Photoinitiator system

In the present invention, the photo-initiation system includes a photosensitive dye compound and a co-initiator, and thus, the photo-initiator system may be a two-component system or a three-component system. The two-component system is a combined system of a dye compound and a hydrogen donor coinitiator, and the three-component system is a combined system of the dye compound, the hydrogen donor coinitiator and a hydrogen acceptor coinitiator.

The photosensitive dye compound is a dye compound having an excitation activity in a range of light-transmittable, and suitable dyes are, for example, Irgacure 784, new methylene blue, thionine, basic red 2, basic red 94, basic yellow, basic violet 4, pinacyanol chloride, rhodamine B, betacyanine, ethyl violet, victoria blue R, azurite blue, quinaldine red, crystal violet, brilliant green, basic orange 21, darura red (darwred), pyronine Y, rose bengal, potato red Y, mikrolone, 3.3' -carbonylbis (7-diethylaminocoumarin), diiodofluorescein, anthocyanin and methylene blue, tiana, crystal violet (leucotritle), malachite green (leucotritle), or the like.

Preferred hydrogen donor coinitiators are at least one selected from the group consisting of N-phenylglycine, 2, 6-diisopropyl-N, N-dimethylaniline, 2- (4-methoxyphenyl) -4, 6-bis (trichloromethyl) -S-triazine.

A preferred hydrogen acceptor co-initiator is bis (4-tert-butylphenyl) iodonium hexafluorophosphate.

In some specific embodiments of the present invention, the content of the photoinitiating system component is 0.1 to 3%, preferably 0.5 to 2%, based on the total weight of the photopolymer composition.

Precursor of noble metal

In the present invention, in order to uniformly disperse the noble metal nanoparticles and to improve the mobility of the noble metal, a noble metal precursor is used to form a photopolymer composition with the aforementioned writing monomer, matrix, and photoinitiating system.

As the noble metal that can be used in the present invention, one or more of 8 kinds of metal elements such as gold, silver, and platinum group metals (ruthenium, rhodium, palladium, osmium, iridium, platinum) may be selected. In some preferred embodiments, the noble metal of the present invention is selected from one or more of Ag, Au, Pt, Pd.

Further, the noble metals of the present invention are used in precursors in the form of acids of the noble metals and/or salts of the noble metals, wherein the salts of the noble metals also include complexes. The acid and/or salt of the noble metal suitable for use in the present invention is not particularly limited, and may be an inorganic acid, an organic acid salt, an inorganic acid salt or a metal complex of these metals. In some specific embodiments, they may be halides, nitrates, complexes of these metals, and hydrates thereof.

In some particular embodiments of the invention, the acid and/or salt of the noble metal is suitable in the form of a dispersion or solution. The solvent used to form the dispersion or solution may be water and/or an organic solvent. As the organic solvent, one or more of an alcohol solvent, a hydrocarbon solvent, an ester solvent, an ether solvent, an amide solvent, or a nitrogen-containing solvent may be suitably used.

In addition, the noble metal precursor of the present invention is used in the form of a solution from the viewpoint of improving dispersibility and mobility of metal ions and efficiency of photochemical reduction reaction described later, and typically, an acid and/or salt of the noble metal and water and/or an alcohol solvent may be used to form a uniform solution so that the metal element present in the form of free ions in the solution occupies a predominant composition.

The acid and/or salt of the noble metal may be selected from the group comprising Ag when forming a solution with water and/or alcohol⁺、Au³⁺、Pt⁴⁺、Pd²⁺Etc. (also including complex ions, e.g. [ Ag (NH) ]₃)₂]⁺、[AuCl₄]^3-、[PtCl₆]^2-). Preferred acids and/or salts of said noble metals are soluble compounds and hydrates thereof, more particularly selected from AgNO₃、Ag(NH₃)₂NO₃、H₃AuCl₄、KAuCl₄·2H₂O、HAuCl₄·4H₂O、NaAuCl₄·2H₂O、KAuCl₄·2H₂O、(NH₄)₂PtCl₆、H₂PtCl₆、H₂PtCl₆·6H₂O、PdCl₂One or more of (a).

In addition, in order to control the morphology (such as particle size and length-diameter ratio) of the metal nanoparticles and improve the dispersibility, a surfactant can be added into the noble metal precursor of the invention. The surfactant may be an anionic surfactant, a cationic surfactant or a nonionic surfactant. Preferably, the surfactants that may be suitable for use in the present invention are selected from one or more of sodium dodecylbenzene sulfonate, sodium dodecylsulfur sulfonate, polyvinylpyrrolidone, cetyltrimethylammonium bromide, oleic acid, oleylamine, trioctylphosphine, polyvinyl alcohol, poly (amide-amine).

Further, to maintain the stability of the acid and/or salt (e.g., noble metal ion or complex ion) of the noble metal in the noble metal precursor, an antioxidant may also be added. There is no particular limitation on the kind and amount of the antioxidant. In some specific embodiments, the antioxidant may be selected from one or more of ascorbic acid, epicatechin, dibutylphenol, t-butyl p-hydroxyanisole, sodium sulfite, sodium bisulfite.

Meanwhile, in the noble metal precursor of the present invention, a pH-adjusting substance may be used as needed to further improve the stability of the system. Typically, these pH-adjusting substances may be various acidic substances.

In some preferred embodiments of the present invention, the noble metal (based on the molar amount of the noble metal element) in the noble metal precursor of the present invention is used in an amount of 0.1M to 10M, preferably 0.3M to 8M, and more preferably 0.5 to 5M, such as 0.8M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M, 4M, 4.5M, 6M, 7M, etc.; the amount of the surfactant in the noble metal precursor may be 0.01 to 1%, preferably 0.05 to 0.8%, and more preferably 0.1 to 0.6%; the amount of the antioxidant to be used may be 0.05 to 5%, preferably 0.1 to 3%, and more preferably 0.5 to 2%. All of the above contents are based on the total weight of the noble metal precursor (solution).

The amount of the pH-adjusting substance to be used is not particularly limited, and the system can be made neutral, weakly acidic or acidic by adding these substances. Such a substance may be an organic acid, an inorganic acid, a strong acid or weak base salt, or the like.

The configuration of the noble metal precursor is not particularly limited, and the components may be mixed by a conventional mixing method. In some specific embodiments, the temperature of mixing is up to no more than 60 ℃, preferably no more than 50 ℃, more preferably no more than 35 ℃. In other specific embodiments, the compounding of each of the above substances may be performed under the protection of an inert gas. In other embodiments, the compounding may be performed using mechanical or magnetic stirring.

Other ingredients

In the present invention, other components commonly used in the art may be used according to actual production needs as long as the technical effects of the present invention are not affected, and the components include: plasticizers, solvents, levelling agents, wetting agents, defoamers or tackifiers, as well as polyurethanes, thermoplastic polymers, oligomers, compounds having additional functional groups (e.g. acetals, epoxides, oxetanes, oxazolines, dioxolanes) and/or compounds having hydrophilic groups (e.g. salts and/or polyethylene oxides), can be used as additional auxiliaries and additives.

The use of a plasticizer can increase the flexibility of the photopolymer composition and relieve the degree of dimensional shrinkage that occurs after film formation and curing. In some particular embodiments, plasticizers suitable for use in the present invention are polymeric materials with good compatibility/dissolution characteristics, low volatility, and high boiling point. Typically, these polymeric materials may be polymeric polyols or glycidyl ethers of polymeric polyols. From the viewpoint of suppressing dimensional shrinkage, in a preferred embodiment of the present invention, the polymeric polyol may be polyethylene glycol, polypropylene glycol, or the like; the glycidyl ether of the polyhydric alcohol can be polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether. For the plasticizer of the present invention, one kind or a combination of two or more kinds may be used. In the present invention, the plasticizer is contained in an amount of 20% or less, for example, 0.5 to 20%, preferably 1 to 15%, and more preferably 2 to 10% based on the total weight of the photopolymer composition.

Of the solvents that can be used, the solvents of choice are readily volatile solvents that have good compatibility with the components of the present invention, such as ethyl acetate, butyl acetate, and/or acetone, among others. It is to be noted that the use of solvents, while generally believed to promote homogeneity of the mixed system and improve the mobility of the components, may also result in significant dimensional shrinkage effects, and therefore, in preferred embodiments of the invention, these additional solvents are not used.

< second aspect >

In a second aspect of the present invention, there is provided a diffraction grating based on the photopolymer composition according to the above < first aspect >, and a method for preparing the same.

The grating includes a carrier layer and a polymer film layer. The carrier substrate used may preferably be a layer of a material or a composite of materials that is transparent in the visible spectrum (greater than 85% transmittance in the wavelength range 400-780 nm).

Preferred materials or material composites for the carrier substrate are based on Polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene, polypropylene, cellulose acetate, cellulose hydrate, cellulose nitrate, cycloolefin polymers, polystyrene, polyepoxides, polysulfones, Cellulose Triacetate (CTA), polyamides, polymethyl methacrylate, polyvinyl chloride, polyvinyl butyral or polydicyclopentadiene or mixtures thereof. They are more preferably based on PC, PET and CTA. The material composite may be a foil laminate or a coextrusion. Preferred material composites are double or triple foils constructed according to one of the embodiments A/B, A/B/A or A/B/C. PC/PET, PET/PC/PET and PC/TPU (TPU ═ thermoplastic polyurethane) are particularly preferred.

As an alternative to the aforementioned carrier substrates, it is also possible to use flat glass plates, which are used in particular for the precise imagewise exposure of large areas, for example for holographic lithography (holographic interference lithography for integrated optics, IEEE Transactionson Electron Devices (1978), ED-25(10), 1193-.

Additionally, in some embodiments of the invention, the material or material composite of the carrier substrate may have a release, antistatic, hydrophobic or hydrophilic finish on one or both sides. The modification mentioned serves the purpose of enabling the non-destructive removal of the photopolymer from the carrier substrate on the side in contact with the photopolymer composition. The modification of the side of the carrier substrate facing away from the photopolymer composition serves to ensure that the media according to the invention meet the specific mechanical requirements, for example in the case of processing in a roll laminator, in particular in the roll-to-roll process. The carrier substrate may have a coating on one side or a coating on both sides.

The thickness of the carrier substrate suitable for use in the present invention may be 1.5mm or less, preferably 20 μm to 1mm, and more preferably 100 μm to 900 μm.

In some specific embodiments of the present invention, the grating may be a laminate of a film formed of a photopolymer composition and the carrier, i.e., the film is formed on the carrier, or the film is sandwiched between two carriers. Therefore, the film formed of the photopolymer in the present invention has a grating structure by exposure, bleaching, or the like, and it may be present as a hologram recording medium on the support or sandwiched between the supports. In other cases, the grating may additionally comprise a cover layer and/or other functional layers, each optionally at least partially associated with the film.

In the present invention, the method for preparing a grating by using the photopolymer composition, the carrier, and the like may include the steps of:

(i) a mixing step, namely mixing all the components of the photopolymer composition to obtain a mixture;

(ii) a step of forming a grating structure by forming a film of the mixture and forming a grating structure on at least a part of the film,

wherein, in the step of forming the grating, a step of exposing the film with coherent light is included, and in some preferred embodiments of the present invention, the coherent light is coherent light having a wavelength around 532 nm.

(i) Step (ii) of

In the present invention, a mixture is obtained by mixing the components of the photopolymer composition.

The compositions are mixed in proportions in a suitable container and, if desired, mechanically agitated or the like to provide uniform mixing. There is no particular limitation on the temperature of mixing, and in general, mixing under ambient conditions at room temperature or under heating conditions may be selected (in particular, if a film-forming ingredient is used as the matrix, heating may be used to cause the photocurable composition to form a liquid or liquid).

In some preferred embodiments of the invention, the blend of the components of the photopolymer composition of the invention takes on a liquid form (e.g., the liquid matrix monomer acts in part as a solvent) which is advantageous for the migration behavior of the writing monomer and the matrix during exposure. The resulting liquid mixture can be used immediately or stored briefly at the processing temperature for use.

(ii) Step (ii) of

In this step, a film is formed on a support by using the liquid mixture obtained above, and subjected to an exposure process to obtain a polymer film having a grating structure. In some specific embodiments of the present invention, the polymer film has a thickness of 15 μm or more, preferably 20 μm or more, and further, the polymer film has a thickness of 50 μm or less, preferably 40 μm or less. The above-mentioned thickness of the polymer film can be coordinated or matched in practice with the use of spacers, for example as described below.

As the material of the support, in a preferred embodiment, glass can be used as the support. Optionally, the carrier glass sheet is cleaned, dried, etc. prior to use.

In the present invention, the grating structure is formed on at least a portion of the photopolymer film by exposure to light, during which exposure to coherent light can be used to control the microstructure.

In addition, in a preferred embodiment of the present invention, the use of spacers in the polymer film is advantageous for process control from the viewpoint of controlling the thickness of the polymer film, suppressing the dimensional shrinkage of the grating, and maintaining high diffraction efficiency, particularly in the case where two carrier layers sandwich one polymer film.

For spacers, in some particular embodiments of the invention, particles that are substantially opaque to visible light may be used. These particles may be inorganic particles, organic particles or metallic particles. The inorganic particles are preferably used in the present invention from the viewpoint of suppressing the dimensional shrinkage of the grating and the production cost.

The kind of the inorganic particles is not particularly limited, and for example, silica, titania, or the like can be used. In some specific embodiments, the inorganic particles have a substantially spherical steric shape; in other specific embodiments, the inorganic particles have an average particle size of 2 to 50 μm, preferably 3 to 40 μm, and the particle size of the spacer may be coordinated, selected or determined with the thickness of the photopolymer film being formed.

As for the method of using the spacer, in the present invention, the spacer may be previously formed on the surface of the support, and this process may be carried out by a method of coating a dispersion system containing the spacer. In some embodiments, the spacer may be dispersed in a hydrocarbon, alcohol, or ketone solvent, for example, to form a dispersion. For these solvents, it is preferable to use a substance having a relatively low boiling point, and examples of the solvent include one or more of benzene, toluene, cyclohexane, pentane, ethanol, isopropanol, acetone, methyl ethyl ketone, and the like. The dried spacer particles (powder) may be directly dispersed in these solvents, or a sol-like substance formed by the spacers may be dispersed in these solvents.

The concentration of the spacer-containing dispersion system may be 0.1 to 3mg/mL, preferably 0.1 to 0.3mg/mL in some specific embodiments of the present invention, and too high a concentration deteriorates the uniformity of dispersion, resulting in a decrease in diffraction efficiency of the grating.

In the present invention, the spacer can be uniformly applied to the surface of the support by a coating method, and the coating method is not particularly limited, and can be performed by a spray coating or spin coating method. After the spacer is formed on the surface of the support by a coating method, the solvent may be removed by heating, blowing, or the like.

Further, the liquid mixture obtained in the step (i) is formed into a film on the surface of the support having the spacer. For example, flat, onto a carrier substrate, in which case, for example, devices known to the person skilled in the art can be used, such as knife coating devices (doctor blades, knife rolls, curved bars (Commabar), etc.) or slit nozzles, etc. Optionally, if desired, a degassing step is carried out after the coating of the film, in order to eliminate possible bubbles in the film. After coating, a photopolymer film can be obtained by cooling or the like.

In the present invention, the above-described photopolymer film that can be used as a holographic medium can be processed into holograms by suitable exposure operations for various optical applications. Visual holograms include all holograms which can be recorded by methods known to those skilled in the art.

In some preferred embodiments of the present invention, the exposure treatment of the photopolymer film can be performed with two beams of coherent light. The source of the coherent light is not particularly limited, and in some specific embodiments of the present invention, the green (around 532 nm) laser beam may be split into two coherent light beams of the same or different intensities by an optical element, and the resulting photopolymer film may be simultaneously exposed.

By using coherent light exposure, it is possible to present spaced bright and dark regions in the photopolymer film (the two beams of coherent light produce alternating bright and dark stripes in the photopolymer film). And (3) transferring and enriching the writing monomer and the noble metal ions to a bright area, wherein the writing monomer is polymerized under the action of an initiator, and simultaneously, the metal ions are subjected to a photochemical reaction under illumination to form metal nano-particle NPs in situ. In the following specific embodiment of the present invention, the average particle diameter of the noble metal nanoparticles may be 1 to 50nm, preferably 1 to 30nm, more preferably 2 to 10nm, and still more preferably 2 to 15 nm. Taking Au as an example, the mechanism of photochemical reduction of Au nanoparticles is:

the average particle size of the noble metal nano can be regulated and controlled by the concentration of the noble metal salt and the dosage of the surfactant.

In addition, in other preferred embodiments of the present invention, the photochemical reduction reaction described above may also be carried out using a precursor containing a plurality of noble metal elements at the same time, and thus, two or more metal composite systems (nanoparticles) may be formed, typically, for example, particles having a core-shell structure may be formed.

Therefore, a refractive index difference Δ n (degree of modulation of refractive index) is formed in a bright area and a dark area due to the migration of writing monomers and noble metal ions, such as the process shown in fig. 1.

In addition, the exposure intensity may be 0.1 to 30mJ/cm in some embodiments of the present invention²It can be seen that the exposure sensitivity of the present invention is very high.

In some embodiments of the present invention, the two beams of coherent light may be exposed simultaneously from both sides of the polymer film (reflective diffraction grating) or from the same side of the polymer film (transmissive diffraction grating). In the above two exposure modes, the grating period can be adjusted by the incident angle of the two coherent lights (i.e. the included angle between the incident light and the normal direction of the polymer film). The incident angle is not particularly limited, and may be adjusted within a range of 0 to 90 °, and in a preferred embodiment, the incident angles of the two coherent light beams are kept the same.

After exposure, refractive index distribution which is distributed in a sine function is formed in the photopolymer film, and the diffraction grating is obtained. The difference between the sinusoidal peaks, i.e., Δ n (degree of refractive index modulation). In some specific embodiments of the invention, Δ n can be 0.020 or more, such as 0.025 or more, 0.030 or more, and the like.

The grating prepared according to the present invention has a diffraction efficiency of 70% or more, preferably 80% or more, and more preferably 90% or more.

For example, fig. 2 shows a specific exposure light path (reflective diffraction grating recording light path) of the present invention, the visible light laser is divided into two laser beams with the same or different intensities after splitting, and the two laser beams are respectively reflected and converged on the photopolymer film (incident angles are α and β, respectively) by the reflector to generate interference fringes.

In addition, the grating obtained by the invention can be a plane grating or a curved grating with a certain curvature.

The method for producing the curved grating is not particularly limited, and in some specific embodiments, a film may be formed on a substrate having a curvature by using the substrate and exposing the substrate. In other embodiments, a planar substrate may be used, and the coating film may be processed into a curved grating with a certain curvature after exposure.

< third aspect >

In a third aspect of the invention, the use of the grating obtained as described above in the invention is disclosed. Without limitation, the above-described gratings comprising photopolymer films of the present invention can be used in a variety of holographic display systems in the art, and can be used alone or in combination with other optical elements.

Further, the present invention provides a grating element for a holographic optical waveguide display system. The element comprises a carrier layer and a photopolymer film layer comprising spacers. The carrier layer, the photopolymer film layer and the spacer are as described or defined in < first aspect > and < second aspect > of the present invention above.

In some preferred embodiments, the grating element is formed by sandwiching a layer of photopolymer film between two carrier layers.

Typically, the grating elements have a regular shape to facilitate use and installation, and may be in the shape of a strip, a square, or a circular plate.

In some preferred embodiments, the grating element of the present invention has an elliptical or elongated sheet shape, and has exposure regions subjected to exposure or the like at both end regions in the length direction, and a grating (holographic recording) structure is formed in each exposure region. And the two exposure areas are physically unconnected. Typically, one exposure area may be used as an incoupling grating area, and the other exposure area may be used as an outcoupling grating area.

The grating element of the present invention can be used in a holographic optical waveguide display device, and is particularly suitable for Augmented Reality (AR) head display devices such as AR display glasses devices and the like.

Examples

Hereinafter, the present invention will be described by way of specific examples.

Examples

5mol/L of tetrachloroauric acid is prepared, and 0.1% of hexadecyl trimethyl ammonium bromide and 0.5% of ascorbic acid are added. 0.45g of polytetrahydrofuran (molecular weight 1000), 0.08g of hexamethylene-1, 6-diisocyanate, 0.45g of tribromophenyl 2,4, 6-acrylate, 0.15g of pentaerythritol tetraacrylate and 0.1mg of dibutyltin dilaurate were stirred uniformly. Then 2mg diiodofluorescein, 5mg 2, 6-diisopropyl-N, N-dimethylaniline were added. Dissolving, adding 10uL of tetrachloroauric acid solution, magnetically stirring for 5min, performing ultrasonic treatment for 30min to uniformly mix the components, defoaming in vacuum, and storing in dark place for later use.

And (3) injecting the mixed solution into a gap between the upper glass sheet and the lower glass sheet, wherein the thickness of the gap is controlled by silicon dioxide microspheres with the particle size of 20 microns, and thus obtaining a photopolymer sample. The sample was placed in the light path shown in FIG. 2 at a laser wavelength of 532nm and an exposure intensity of 10mW/cm²And (3) adopting a symmetrical reflection type for incident light, wherein α is equal to 45 degrees, β is equal to 45 degrees, exposing is carried out for 30s, and after the exposing is finished, a sample is placed under an LED lamp to irradiate for 5min, so that the reflection type holographic volume grating is obtained.

The diffraction efficiency of the grating can reach 90% at most according to the characteristic curve of the change of the Bragg deviation angle shown in FIG. 3, and the delta n is 0.025%.

Comparative example

Gratings were prepared by the same method as in example, except that tetrachloroauric acid was not used. The diffraction efficiency of the obtained grating is less than 80% at most, and Δ n is 0.015, as shown in fig. 3.

It should be noted that, although the technical solutions of the present invention are described by specific examples, those skilled in the art can understand that the present disclosure should not be limited thereto.

Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Industrial applicability

The photopolymer composition of the present invention can be used industrially for the production of diffraction gratings.

Claims (10)

1. A photopolymer composition comprising:

the writing unit is a single body for writing,

a substrate, wherein the substrate is a glass substrate,

a photoinitiator system, and

a precursor of the noble metal is prepared,

the noble metal precursor includes an acid and/or a salt thereof of a noble metal.

2. The composition of claim 1, wherein the noble metal is selected from one or more of Ag, Au, Pt, Pd.

3. The composition according to claim 1 or 2, characterized in that the precursor of the noble metal further comprises a surfactant and/or an antioxidant.

4. The composition according to any one of claims 1 to 3, wherein the noble metal precursor is a solution containing an acid of the noble metal and/or a salt thereof, the solvent in the solution is selected from water and an organic solvent, and the concentration of the acid of the noble metal or the salt thereof in the solution is 0.1M to 10M in terms of the noble metal element.

5. The composition as claimed in any one of claims 1 to 4, wherein the writing monomer comprises an acrylate monomer and/or an epoxy compound having a refractive index of 1.50 or more.

6. The composition according to any one of claims 1 to 5, wherein the writing monomer is contained in an amount of 30 to 60% by mass based on the total mass of the composition; the content of the matrix is 20-50%; the content of the noble metal precursor is 0.01-5%.

7. A diffraction grating comprising a resin film having a grating structure, wherein the resin film is obtained by curing the composition according to any one of claims 1 to 6.

8. A method for manufacturing a diffraction grating is characterized by comprising the following steps:

a mixing step, mixing the components of the composition according to any one of claims 1 to 6 to obtain a mixture;

a step of forming a grating structure by forming a film of the mixture and forming a grating structure on at least a part of the film,

wherein the step of forming a grating structure includes a step of exposing the film with coherent light.

9. The method of claim 8, wherein the step of forming a grating structure comprises the step of using spacers to compound the hybrid.

10. A holographic optical waveguide display element comprising a diffraction grating according to claim 7 or a diffraction grating obtained by a method according to any one of claims 8 to 9.

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