KR20060134088A - Process for preparing a polymeric relief structure - Google Patents

Abstract

The invention deals with a process for the preparation of a polymeric relief structure via electromagnetic radiation. In the process a compound is used that reduces the interfacial tension of the coated substrate. As a result the aspect ratio as well as the curvature of the surface are enhanced, and therefore are beneficial for optical components and for replication purposes.

Description

PROCESS FOR PREPARING A POLYMERIC RELIEF STRUCTURE}

The present invention relates to a method of making a coated substrate comprising (a) coating a substrate with a coating comprising one or more radiation-sensitive components, and (b) locally applying the coated substrate with electromagnetic radiation having a periodic or random line-strength pattern. To form a latent image, and (c) polymerizing and / or crosslinking the resulting coated substrate to produce a polymer relief structure.

This method, also referred to as "photo-embossing", is described in "photo-embossing as a tool for complex surface relief structures", De Witz, Christiane, Broer, Dirk J. 226th ACS National Meeting, New York, NY, September 7-11, 2003.

In recent years, considerable attention has been paid to polymers used in optical systems for data transmission, storage and display. By imparting a structure to the surface of the polymer film or layer, the light passing through these layers can be controlled. For example, if the surface structure contains small hemispherical elements, a lens array capable of concentrating transmitted light is obtained. Such elements are useful, for example, in the backlight of liquid crystal displays for focusing light in transparent areas of the display. For this type of use, it is often necessary to lower the shape of the structural profile to a micrometer area. In addition, the regular pattern of the surface structure can diffract the light to split the single beam into multiple beams that can be used, for example, as beam splitters in telecommunication devices, in transmission. Surface structures are also important for controlling the refractive index of light. This can be successfully applied to suppress the specular reflection of the surface. This so-called anti-glare effect is applied to the front screen of a television set, for example. However, it is also used in applications such as glazing, automotive finishes and the like. A conformal reflective film such as evaporated aluminum or sputtered silver can be provided in a polymer film having a well-defined surface profile. Incident light incident on this mirror is distributed in space in a highly controlled manner upon reflection. It is used for example to manufacture internal diffuse reflectors for reflective liquid crystal displays. Another use of surface profiles is to create antifouling structures known as the Lotus effect. This requires a surface profile with dimensions smaller than 1 μm.

Electromagnetic radiation induced polymerization, such as UV photo-polymerization, is, for example, a method of making a device from a mixture of two (meth) acrylate monomers and a photo-initiator. The polymerization reaction is initiated only in the region where UV light can activate the photo-initiator. In addition, the light intensity can be changed according to the space, and thus the polymerization rate can be changed. Differences in monomer reactivity, size or length, crosslinking capacity, and strong interactions create gradients in the chemical potential of the monomers. These chemical potentials create driving forces for monomer migration and polymer infiltration in the illuminated area. The monomer diffusion coefficient determines the time-scale at which this shift occurs. The entire film is then polymerized using uniform UV illumination with higher intensity than during patterned UV illumination.

Thus, the polymer structure is produced by patterned UV photo-polymerization of a mixture of two liquid monomers. This can be done by holography or lithography. In the case of holography, the interference pattern of two coherent light beams produces regions of high and low light intensity. In the case of lithography, a photo-mask is used to create these intensity differences. For example, in the case of using a striped mask, a grid shape is generated. When a mask having a circular hole is used, a microlens structure is generated. The difference in refractive index is caused by the lateral variation of the monomer-unit concentration in the polymer.

A better way to produce the surface structure is to use a blend consisting essentially of a blend of polymers, monomers and initiators. The polymer may be a single polymer material, but may also be a blend of more than one polymer. Similarly, the monomer may be a single compound, but may also consist of several monomer materials. The initiator is preferably a photoinitiator, but sometimes it is a mixture of a photoinitiator and a thermal initiator. In order to improve the formation of thin films by processing, such as by spin coating, this mixture is usually dissolved in an organic solvent. Blending conditions and properties of the polymer and monomer are chosen such that a solid film is produced after evaporation of the solvent. In general, a latent image can be formed upon exposure patterned to UV light. Heating can cause polymerization and diffusion at the same time, thus increasing the material volume in the exposed zones and vice versa, thereby creating a surface deformation, thereby developing the latent image into a surface profile.

The disadvantage of this method is that the resulting relief structures produced by this photo-embossing method have a significantly lower aspect ratio. Aspect ratio AR is defined as the ratio of the distance (or pitch) between relief height and neighboring reliefs. The edges of the relief structure are not sharp or accurately reproduced because the desired optical or other function is less than optimal.

1 is an atomic micrograph of an embossed structure prepared in Comparative Experiment A. FIG.

2 is an atomic micrograph of an embossed structure prepared using silicone oil in Example I. FIG.

3 is an atomic micrograph of an embossed structure prepared by holography in Comparative Experiment B. FIG.

4 is an atomic micrograph of an embossed structure prepared by holography using silicone oil in Example II.

The present invention provides an improved method for producing a polymer relief structure, characterized by the presence of compound (Cs) which reduces the surface tension of the interface of the coated substrate during step (c) of light embossing.

As a result, an embossed structure is obtained having an improved relief aspect ratio (an improvement typically shows a more than twofold increase) and an edge with much sharper relief.

Compounds (Cs) used to reduce the surface tension of the interface can be applied in two or more separate ways. The first method is a method of performing step (c) after applying Cs to the coated substrate produced from step (b) of the method. The second way is to pre-exist Cs in the coating used in step (a) of the process. As a result, Cs is present in steps (b) and (c).

The coating used in step (a) of the process generally comprises one or more line sensitive components which are C = C unsaturated monomers which can be polymerized via electromagnetic radiation. These components can be used on their own and also in the form of solutions.

The coating can be applied onto the substrate by any method known in the (wet) coating deposition art. Examples of suitable methods are spin coating, dip coating, spray coating, flow coating, meniscus coating, doctor blading, capillary coating and roll coating.

Typically, the linearly sensitive constituent is preferably mixed with one or more solvents and optionally a crosslinking initiator to produce a mixture suitable for application to the substrate using the chosen application method.

In principle, various solvents can be used. However, the combination of solvent and all other materials present in the mixture should preferentially produce a stable suspension or solution.

Preferably, the solvent used is evaporated after applying the coating on the substrate. In the process according to the invention, the coating is optionally applied to a substrate and then heated or treated in vacuo to help evaporate the solvent.

Examples of suitable solvents are 1,4-dioxane, acetone, acetonitrile, chloroform, chlorophenol, cyclohexane, cyclohexanone, cyclopentanone, dichloromethane, diethyl acetate, diethyl ketone, di Methyl carbonate, dimethylformamide, dimethylsulfoxide, ethanol, ethyl acetate, m-cresol, mono- and di-alkyl substituted glycols, N, N-dimethylacetamide, p-chlorophenol, 1,2-propanediol, 1-pentanol, 1-propanol, 2-hexanone, 2-methoxyethanol, 2-methyl-2-propanol, 2-octanone, 2-propanol, 3-pentanone , 4-methyl-2-pentanone, hexafluoroisopropanol, methanol, methyl acetate, butyl acetate, methyl acetoacetate, methyl ethyl ketone, methyl propyl ketone, n-methylpyrrolidone-2, n-pentyl acetate, phenol Tetrafluoro-n-propanol, tetrafluoroisopropane , Tetrahydrofuran, toluene, xylene, and water is alkylene. The use of high molecular weight alcohols may be a problem of acrylate solubility, but alcohols, ketones and ester solvents may also be used. Halogenated solvents such as dichloromethane and chloroform and hydrocarbons such as hexane and cyclohexane are suitable.

The mixture preferably contains a polymeric material. Indeed, it is possible to use individual polymers which produce a homogeneous mixture with other components. Well studied polymers are polymethyl methacrylate, polymethyl acrylate, polystyrene, polybenzyl methacrylate, polyisobonyl methacrylate. Many other polymers may also be applied. The mixture also contains monomeric compounds, which are compounds of relatively low molecular weight, ie smaller than 1500, which polymerize when contacted with reactive particles, ie free radicals or cationic particles. In a preferred embodiment, one of the monomers or monomers of the monomer mixture contains more than one polymerizable group which allows to produce a polymer network upon polymerization. In a preferred embodiment, the monomer is also a molecule containing reactive groups of the following classes: vinyl, acrylate, methacrylate, epoxide, vinylether or thiol-ene. The mixture also contains a photosensitive component which is a compound that generates reactive particles, ie free-radical or cationic particles upon exposure to actinic radiation.

Examples of monomers suitable for use as polymerization components and having two or more crosslinkable groups per molecule include trimethylolpropane tri (meth) acrylate, pentaerythritol (meth) acrylate, ethylene glycol di (meth) acrylic Rate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di ( Meth) acrylate, neopentyl glycol di (meth) acrylate, polybutanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, glycerol tri (meth) acrylate acid, phosphoric acid mono- and di (meth) acrylates, C ₇ -C ₂₀ alkyl di (meth) acrylate, trimethylol pro paint Lai oxyethyl (meth) acrylate, tris (2-hydroxy Ciethyl) isocyanurate tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) Acrylates, dipentaerythritol monohydroxy pentaacrylate, dipentaerythritol hexaacrylate, tricyclodecane diyl dimethyl di (meth) acrylate and alkoxylated, preferably ethoxylated and / or propoxy Any of the above monomers emulsified and di (meth) acrylates of diols which are ethylene oxide or propylene oxide adducts to bisphenol A, di (meth) acrylates of diols which are ethylene oxide or propylene oxide adducts to hydrogenated bisphenol A, Is a (meth) acrylate adduct of diglycidyl ether to bisphenol A Adducts of epoxy (meth) acrylates, diacrylates of polyoxyalkylated bisphenol A and triethylene glycol divinyl ether, hydroxyethyl acrylate, isophorone diisocyanate and hydroxyethyl acrylate ( HIH), hydroxyethyl acrylate, toluene diisocyanate and (meth) acryloyl group-containing monomers such as adducts of hydroxyethyl acrylate (HTH) and amide ester acrylates.

Examples of suitable monomers having only one crosslinking group per molecule include monomers containing vinyl groups such as N-vinyl pyrrolidone, N-vinyl caprolactam, vinyl imidazole, vinyl pyridine; Isobonyl (meth) acrylate, Bonyl (meth) acrylate, tricyclodecaneyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, cyclohexyl (meth) Acrylate, benzyl (meth) acrylate, 4-butylcyclohexyl (meth) acrylate, acryloyl morpholine, (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth ) Acrylate, 2-hydroxybutyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate , Amyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, caprolactone acrylate, isoamyl (meth) Acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, Decyl (meth) acrylate, isodecyl (meth) acrylate, tridecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (Meth) acrylate, tetrahydrofurfuryl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth ) Acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) acrylate, ethoxyethyl (meth) Acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, diacetone (meth) acrylamide, beta-carboxyethyl (meth) acrylate, phthalic acid (meth) Acrylate, isobutoxymethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, tert-octyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl ( Meth) acrylate, butylcarbamylethyl (meth) acrylate, n-isopropyl (meth) acrylamide fluorinated (meth) acrylate, 7-amino-3,7-dimethyloctyl (meth) acrylate, N , N-diethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, hydroxybutyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether, 2-ethylhexyl vinyl ether; And a compound represented by formula (I); And alkoxylated aliphatic monofunctional monomers such as ethoxylated isodecyl (meth) acrylate, ethoxylated lauryl (meth) acrylate, and the like:

CH ₂ = C (R ⁶ ) -COO (R ⁷ O) _m -R ⁸

Where

R ⁶ is a hydrogen atom or a methyl group;

R ⁷ is an alkylene group containing 2 to 8, preferably 2 to 5 carbon atoms;

m is an integer of 0 to 12, preferably 1 to 8;

R ⁸ is a hydrogen atom or an alkyl group containing 1 to 12, preferably 1 to 9 carbon atoms, or R ⁸ is a carbon atom 4 to 20 optionally substituted by an alkyl group having 1 to 2 carbon atoms Is a tetrahydrofuran group containing 3 alkyl groups, or R ⁸ is a dioxane group containing 4 to 20 carbon atoms optionally substituted with a methyl group, or R ⁸ is a C ₁ -C ₁₂ alkyl group, preferably Aromatic groups optionally substituted with C ₈ -C ₉ alkyl groups.

Oligomers suitable for use as pre-sensitive components include, for example, oligomers based on aromatic or aliphatic urethane acrylates or phenolic resins such as bisphenol epoxy diacrylates, and any of the foregoing chain-extended with ethoxylates Oligomers. The urethane oligomers can be based, for example, on polyol backbones such as polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone polyols, acrylic polyols and the like. These polyols can be used individually or in combination of two or more. There is no restriction | limiting in particular about the polymerization system of the structural unit of these polyols. Any method of random polymerization, block polymerization or graft polymerization can be used. Examples of polyols, polyisocyanates and hydroxyl group-containing (meth) acrylates suitable for preparing urethane oligomers are disclosed in WO 00/18696, which is incorporated herein by reference.

Combinations of compounds which can form a crosslinked phase together and are thus combined to be suitable for use as reactive diluents are for example carboxylic acids and / or carboxylic anhydrides, hydroxy compounds (especially 2-hydroxyalkylamides) in combination with epoxy. In combination with acids, isocyanates (such as blocked isocyanates), urethanedione or carbodiimide in combination with amines, amines or dicyandiamides in combination with epoxy, isocyanates Hydrazineamides, isocyanates (such as blocked isocyanates), hydroxy compounds in combination with uretdione or carbodiimide, hydroxy compounds in combination with anhydrides, (etherified) methylolamide ( Hydroxy compound in combination with "amino-resin", thiol in combination with isocyanate, acrylate Is an epoxy or hydroxy compounds and epoxy compounds when the acetoacetate, and cationic cross-linking in combination with other vinyl compounds (optionally radical initiated search) and the combined thiol, acrylate is used.

Other possible compounds that can be used as the line sensitive constituents are moisture curable isocyanates, moisture curable mixtures of alkoxy / acyloxy-silanes, alkoxy titaniumates, alkoxy zirconates, or urea-, urea / melamine-, melamine- Formaldehyde or phenol-formaldehyde (resol, novolac type), or radically curable (peroxide- or photo-initiated) ethylenically unsaturated monofunctional and multifunctional monomers and polymers, such as acrylates, methacrylates, Mali Radical / curable (peroxide- or photo-initiated) unsaturated maleic or fumaric acid polyesters in ate / vinyl ether, or styrene and / or methacrylate.

Preferably, the coating agent to be applied also includes polymers which preferably have the same properties as the polymers resulting from crosslinking of the linearly sensitive constituents. Preferably, this polymer has a weight-average molecular weight (Mw) of at least 20,000 g / mol.

The polymer used in the coating step (a) preferably has a glass transition temperature of at least 300K. Preferably, the polymer in the coating used in step (a) is dissolved in the monomer (s) and is present in the line sensitive coating of step (a) or in the solvent used in the coating of step (a) of the process of the invention. .

In the method according to the invention various substrates can be used as substrates. Suitable substrates are, for example, polycarbonate, polyester, polyvinyl acetate, polyvinyl pyrrolidone, polyvinyl chloride, polyimide, polyethylene naphthalate, polytetrafluoro-ethylene, nylon, films of polynorbornene, or Flat or bent hard or flexible polymer substrates, including microcrystalline solids (eg glass) or crystalline materials (eg silicon arsenide or gallium arsenide). Metal substrates can also be used. Preferred substrates for use in display applications are, for example, glass, polynorbornene, polyethersulfone, polyethylene terephthalate, polyimide, cellulose triacetate, polycarbonate and polyethylene naphthalate.

An initiator may be present in the coating to initiate the crosslinking reaction. The amount of initiator can vary widely. Suitable amounts of initiator are, for example, from 0 to 5% by weight relative to the total weight of the compounds participating in the crosslinking reaction.

When initiating crosslinking using UV-crosslinking, the mixture preferably comprises a UV-photo-initiator. Photo-initiators can initiate crosslinking reactions upon light absorption; The UV-light-initiator therefore absorbs light in the ultraviolet region of the spectrum. Any known UV-photo-initiator can be used in the process according to the invention.

Preferably, the polymerization initiator comprises a mixture of photoinitiator and thermal initiator.

Any crosslinking method which can polymerize and / or crosslink the coating to produce the final coating is suitable for use in the process according to the invention. Suitable modes for initiating crosslinking are, for example, water addition when electron beam rays, electromagnetic radiation (UV, visible and near infrared), heat and moisture-curable compounds are used. In a preferred embodiment, crosslinking is by UV-rays. UV-crosslinking can be through free radical mechanisms or cationic mechanisms, or a combination thereof. In another preferred embodiment, the crosslinking is by heat.

In step (b) of the process of the invention, the coated substrate produced in process step (a) is locally treated with electromagnetic radiation having a periodic or intermittent line intensity pattern to produce a latent image. In one preferred embodiment, this treatment is carried out using UV-light with a mask. In another preferred embodiment, this treatment is performed by using optical interference / holography. Another embodiment is to use electron beam lithography.

An essential feature of the invention is the use of compounds (Cs) which reduce the interfacial tension between the photo-polymer and its surroundings. For this term, "Polymer Surfces", F. Garbossi et al., Wiley 1994, which describe a method for determining the interfacial tension of air and solids by using a Zisman-plot. , Pages 183-184. In order to achieve and evaluate the advantages of the present invention, it is first necessary to determine the interfacial tension (with air) of the coated substrate obtained using all components except Cs, and then use the values obtained with all components ( It is therefore appropriate to compare the interfacial tension of the coated substrates obtained (including Cs) (see Freyer et al., Macromolecules, 2001, 34, pages 5627-5634). Preferably, Cs reduces the interfacial tension by 10 mJ / m ² or more.

Suitable components as compound Cs are compounds which lower the surface tension of the coated substrate.

Cs need not be miscible and soluble in the polymer coating. This means that Cs needs to be nonpolar when polar polymer coatings are used, while Cs needs to be polar when nonpolar coatings are used. Preferably, Cs has one or more of the following properties: non-elastic or non-viscoelastic; Low viscosity; Little or no volatility; Extractable / removable from the coated substrate after process step (c). As a result, it is preferable to use oil as the compound Cs. As nonpolar oils, mention may be made of silicone oils, paraffin oils, and (and) -fluorinated oils. As polar oils mention may be made of glycerol, (poly-) ethylene glycol.

Cs is preferably used in an amount of 0.01 to 1000% by weight relative to the amount of the coating agent, more preferably 0.05 to 500% by weight.

The conditions under which process steps (a) to (c) must be carried out are known per se in the art of prepolymerisation. As the temperature of the process step, preferably 175 to 375 K is used in step (b) and 300 to 575 K is used in step (c).

The polymeric relief structures of the present invention have improved aspect ratios and improved sharpness. The aspect ratio of the relief of the present invention (a beam of AR, relief height and distance between neighboring reliefs, both in μm) is generally at least 0.075, more preferably at least 0.12, even more preferably at least AR is 0.2. The sharpness of the relief structure can be quantified by the maximum absolute value of curvature k. The procedure for deriving the curvature k from the AFM measurements is as follows: (i) fitting the shape of the relief structure, for example to a Boltzmann fit; (ii) calculating first and second differential coefficients of goodness of fit; (iii) The curvature k is calculated according to the following equation:

The maximum absolute value of the curvature of the relief structure according to the present invention (│k _max │) is 0.35㎛ ^-1, more preferably at 0.45㎛ ^-1 or more, still more preferably 0.65㎛ ^-1 or greater, and most preferably 0.7 Μm ^-1 or more. Two parameters (aspect ratio and sharpness) must be determined by atomic force microscopy (AFM).

The polymeric embossed structures of the present invention can be applied to optical components. Examples thereof are, for example, quarter wave films and wire grid polarizers for LCDs and LEDs. Moth eyes or lotus constructs for self-cleaning surfaces can also be obtained using this. Another preferred embodiment is to use a polymeric embossed structure as a disc for replicating in organic or inorganic materials.

The invention is further illustrated by the following examples and comparative experiments which are not meant to limit the invention.

Comparative Experiment A

The photopolymer is a mixture containing (i) 50% weight / weight of polybenzyl methacrylate (Mw = 70 kg / mol) as polymer and (ii) 50% weight / weight of di-penta erythritol tetraacrylate as polyfunctional monomer It consisted of This mixture contains a photo-initiator [Irgacure 369, 4% weight / weight] and a thermal initiator active at 130 ° C. [dicumyl peroxide, 2,5-bis (tert-butyl peroxy) -2, 5-dimethyl hexane] was added. The finished mixture was dissolved in propylene glycol methyl ether acetate (25% weight / weight).

The dissolved mixture was doctor bladed on a glass substrate. After doctor blading, the substrate with the thin film (4-5 μ) was heated to 80 ° C. for 5 minutes to remove traces of residual solvent. A solid film having a glass transition temperature (Tg> 20 ° C.) higher than room temperature was obtained on the glass substrate. A photomask with a lattice (pitch = 10μ) was used in direct contact with the solid polymer film. It was exposed to ultraviolet light (xenon lamp, bandpass interface filter, 365 nm, 0.1 J / cm ² ). Thereafter, the first heating step was performed at 80 ° C. (10 minutes) and the second heating step was performed at 130 ° C. (10 minutes).

Embossed structures were generated and analyzed using atomic force microscopy (AFM) (FIG. 1). The embossed structure had a height of about 1.1 μm and the top of the embossed structure had an outline with rounded edges, which did not exactly mimic the geometry of the photomask. Aspect ratio AR was 0.11, and the maximum value of curvature was 0.3 micrometer <^-1> .

1: AFM micrograph of embossed structure

Example  I

The photopolymer used was the same as in Comparative Experiment A. Rotational coating and exposure to ultraviolet light were performed in the same manner as in Comparative Experiment A.

After exposure to UV-light, a film of silicone oil was applied to a substrate having a film for photopolymerization. The interfacial surface tension was reduced by 18 mJ / m ² .

Special care has been taken so that the oil does not dissolve into the photopolymer. The first and second heating steps were then carried out (see Comparative Experiment A). Thereafter, the silicone oil was removed by washing with heptane at room temperature.

Embossed structures were generated and analyzed by AFM (FIG. 2). The relief structure had a height of about 1.9μ. In addition, very sharp shapes were observed on top of the relief structure, where the illuminated (transparent) areas of the photomask were excellently modeled. Aspect ratio AR was 0.19 and the maximum value of curvature was 0.8 micrometer <^-1> .

2: AFM micrograph of relief structure (with silicone oil)

Comparative Experiment B

The coated substrate of Comparative Experiment A was used for holographic exposure (lattice, pitch = 1.2 μ, argon ion laser, 351 nm, 0.1 J / cm ² ). Thereafter, a first heating step was performed at 80 ° C. (10 minutes) and a second heating step was performed at 130 ° C. (10 minutes). Embossed structures were generated and analyzed using atomic force microscopy (FIG. 3). The relief structure had a height of about 0.07μ. Aspect ratio AR was 0.06.

Figure 3: AFM micrograph of relief structure (holography)

Example II

The coated substrate of Comparative Experiment A was used. After holographic exposure under the same conditions as in Comparative Experiment B, a film of silicone oil was applied to a substrate having a photopolymer film. Particular care was taken to ensure that the oil did not dissolve into the photopolymer. The first and second heating steps were then carried out (see comparative experiment B). Thereafter, the silicone oil was removed by washing with heptane at room temperature.

Embossed structures were generated and analyzed by AFM (FIG. 4). The relief structure had a height of about 0.16μ. Aspect ratio AR was 0.13.

4: AFM micrograph of embossed structure (holography with silicon oil)

Claims (27)

(a) coating the substrate with a coating comprising one or more radiation-sensitive components, and (b) locally treating the coated substrate with electromagnetic radiation having a periodic or random line-strength pattern. To form a latent image, and (c) polymerizing and / or crosslinking the resulting coated substrate, thereby producing a polymer relief structure, Wherein the compound (Cs) is present which reduces the interfacial tension of the coated substrate in step (c). The method of claim 1, The method of applying Cs to the resulting coated substrate of step (b). The method of claim 1, Cs is already present in the coating used in step (a). The method according to any one of claims 1 to 3, The pre-sensitive component (s) of step (a) comprise at least one monomer together with at least one polymerization initiator. The method according to any one of claims 1 to 4, The process in step a) also comprises a polymer. The method of claim 4, wherein The polymerization initiator is a mixture of photo-initiator and thermal initiator. The method according to any one of claims 1 to 6, The coating is a solid film after evaporation of volatile solvent. The method according to any one of claims 1 to 7, A method of using a lithographic mask in direct contact with a photo-polymer film. The method according to any one of claims 1 to 8, The electromagnetic radiation is UV-light combined with a mask. The method according to any one of claims 1 to 8, The process in step (b) uses optical interference / holography. The method according to any one of claims 1 to 10, Wherein the substrate comprises a polymer. The method of claim 5, The polymer in the coating of step a) has a weight average molecular weight (Mw) of at least 20,000 g / mol. The method of claim 5 or 12, The polymer in the coating of step a) has a glass transition temperature of at least 300K. The method according to any one of claims 5, 12 and 13, The polymer is dissolved in the monomer (s) of the pre-sensitive coating used in step a). The method according to any one of claims 1 to 14, The component (s) of the pre-sensitive coating is selected from the group comprising (meth-) acrylate, epoxy, vinyl ether, styrene and thiol-ene. The method according to any one of claims 1 to 15, Cs decreases interfacial tension by 10 mJ / m ² or more. The method according to any one of claims 1 to 16, A method of applying Cs in an amount of 0.05 to 5% by weight relative to the amount of coating. 18. A polymer relief structure obtainable by the process according to any one of claims 1 to 17. The method of claim 18, A polymer embossed structure having an aspect ratio (AR) of at least 0.12, which is the ratio of emboss height and distance between neighboring embosses. The method of claim 18 or 19, A polymer embossed structure having a maximum absolute value of curvature (k _max ) of 0.35 or more, more preferably 0.45 or more, even more preferably 0.65 μm ⁻¹ . The method according to any one of claims 18 to 20, A polymer embossed structure having an AR of at least 0.2. The method according to any one of claims 18 to 21, A polymer embossed structure having k _max of at least 0.7 μm ⁻¹ . The method according to any one of claims 1 to 17, The process of performing step (b) at 175 to 375 K. The method according to any one of claims 1 to 17 and 23, The process of performing step (c) at 300 to 575 K. Light-management of a polymer relief structure made by the method according to any one of claims 18 to 22 or by any one of claims 1 to 17, 23 and 24. ) Usage. The method of claim 25, Use in diffraction- or holography-optical devices. A process according to any one of claims 18 to 22 or as a disc for replication purposes in an organic or inorganic material, or according to any one of claims 1 to 17 and 23 to 25. The use of the polymeric embossed structure.

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