Methods of making nanostructured surfaces and articles made by the method

Abstract

The present disclosure provides a method including placing a substrate on a cylindrical electrode in a vacuum vessel, introducing at a first location in the vacuum vessel a first gaseous species capable of depositing a layer onto the substrate when formed into a plasma, and introducing at a second location in the vacuum vessel a second gaseous species capable of etching the substrate when formed into a plasma. The first location is closer to an entrance of the vacuum vessel at an unwind side than to the second location. The method further includes generating a plasma from the first gaseous species and the second gaseous species between the cylindrical electrode and a counter-electrode, rotating the cylindrical electrode to translate the substrate, and exposing a major surface of the substrate to the plasma. A layer is deposited on at least a portion of the major surface of the substrate and the substrate is etched, thereby forming nanostructures including at least one of nano-pillars, nano-columns, or continuous nano-walls including nano-pillars or nano-columns. An article is also provided, made by the method.

Description

METHODS OF MAKING NANOSTRUCTURED SURFACES AND ARTICLES MADE BY THE METHOD SUMMARY

[0001] In a first aspect, a continuous method for making a nanostructured surface is provided. The method comprises placing a substrate on a cylindrical electrode in a vacuum vessel, introducing at a first location in the vacuum vessel a first gaseous species capable of depositing a layer onto the substrate when formed into a plasma, and introducing at a second location in the vacuum vessel a second gaseous species capable of etching the substrate when formed into a plasma. The first location is closer to an entrance of the vacuum vessel at an unwind side than to the second location. The method further comprises generating a plasma from the first gaseous species and the second gaseous species between the cylindrical electrode and a counter-electrode, rotating the cylindrical electrode to translate the substrate, and exposing a major surface of the substrate to the plasma. A layer is deposited on at least a portion of the major surface of the substrate and the substrate is etched, thereby forming nanostructures comprising at least one of nano-pillars, nano-columns, or continuous nano-walls comprising nano-pillars or nano- columns.

[0002] In a second aspect, an article is provided. The article is made according to the method of any embodiment of the first aspect, and has nano-pillars or nano-columns.

[0003] Various aspects and advantages of exemplary embodiments of the disclosure have been summarized. The above Summary is not intended to describe each illustrated embodiment or every implementation of the present certain exemplary embodiments of the present disclosure. The Drawings and the Detailed Description that follow more particularly exemplify certain preferred embodiments using the principles disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The disclosure may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying figures, in which:

[0005] FIG.1 is a flow chart of a continuous method of making a nanostructured surface, according to various exemplary embodiments disclosed herein;

[0006] FIG.2A is a generalized schematic top view of a comparative Configuration A of a chamber for forming nanostructures;

[0007] FIG.2B is a generalized schematic top view of a Configuration B of a chamber for forming nanostructures, according to various exemplary embodiments disclosed herein;

[0008] FIG.3A is a generalized schematic side view of a Configuration B of a chamber for forming nanostructures, according to various exemplary embodiments disclosed herein;

[0009] FIG.3B is a rotated side view of Configuration B of FIG.3A, according to various exemplary embodiments disclosed herein;

[0010] FIG.4 is a generalized schematic cross-sectional view of an exemplary article, according to various exemplary embodiments disclosed herein;

[0011] FIG.5 is a generalized schematic cross-sectional view of another exemplary article, according to various exemplary embodiments disclosed herein;

[0012] FIG.6 is a generalized schematic perspective view of a further exemplary article, according to various exemplary embodiments disclosed herein;

[0013] FIG.7A is a scanning electron microscopy (SEM) image of a cross-section of a portion of a control article;

[0014] FIG.7B is an SEM image of a cross-section of a portion of an exemplary article made according to various exemplary embodiments disclosed herein;

[0015] FIG.8A is an SEM image of a cross-section of a portion of another control article;

[0016] FIG.8B is an SEM image of a cross-section of a portion of another exemplary article made according to various exemplary embodiments disclosed herein;

[0017] FIG.9 is a graph of average nanostructure height versus HMDSO exposure for CE SET 1 and EX SET 1; and

[0018] FIG.10 is a graph of average nanostructure height versus HMDSO exposure for CE SET 2 and EX SET 2.

[0019] In the drawings, like reference numerals indicate like elements. While the above-identified drawings, which may not be drawn to scale, set forth various embodiments of the present disclosure, other embodiments are also contemplated, as noted in the Detailed Description. In all cases, this disclosure describes the presently disclosed disclosure by way of representation of exemplary embodiments and not by express limitations. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of this disclosure. DETAILED DESCRIPTION

[0020] For the following Glossary of defined terms, these definitions shall be applied for the entire application, unless a different definition is provided in the claims or elsewhere in the specification. Glossary

[0021] Certain terms are used throughout the description and the claims that, while for the most part are well known, may require some explanation. It should be understood that:

[0022] The term “fluoropolymer” refers to any organic polymer containing fluorine.

[0023] The terms “(co)polymer” or “(co)polymers” includes homo(co)polymers and (co)polymers, as well as homo(co)polymers or (co)polymers that may be formed in a miscible blend, (e.g., by coextrusion or by reaction, including, (e.g., transesterification)). The term “(co)polymer” includes random, block and star (co)polymers.

[0024] The term “adhesive” refers to pressure-sensitive adhesives and / or hot melt adhesives.

[0025] As used herein, “adjacent” encompasses both in direct contact (e.g., directly adjacent) and having one or more intermediate layers present between the adjacent materials.

[0026] As used herein, “attached” encompasses both directly attached and being attached via one or more intermediate layers present between the attached materials.

[0027] The term “anisotropic” refers to having a height to width (that is, average width) ratio of about 1.5:1 or greater (preferably, 2:1 or greater; more preferably, 5:1 or greater).

[0028] The term “nanoscale” refers to submicron (for example, between about 1 nm and about 500 nm).

[0029] The term “nanostructured” refers to having at least one dimension on the nanoscale. Typically, a nanostructure is three-dimensional.

[0030] The term “plasma” refers to a partially ionized gaseous or fluid state of matter containing electrons, ions, neutral molecules, and free radicals.

[0031] The term “metal” includes a pure metal or a metal alloy.

[0032] The term “film” or “layer” refers to a single stratum within a multilayer film.

[0033] The term “substrate” encompasses films, layers, and articles.

[0034] As used herein, “thickness” refers to the smallest dimension of a film or layer, e.g., in a z-axis while a major surface of the film or layer is in the x- and y-axes. Thickness may be determined using a micrometer gauge or doing a microscopic analysis of a cross-sectional sample of a layer or an article.

[0035] The term “(meth)acryl” or “(meth)acrylate” with respect to a monomer, oligomer, (co)polymer or compound means a vinyl-functional alkyl ester formed as the reaction product of an alcohol with an acrylic or a methacrylic acid.

[0036] The term “optically clear” refers to an article in which there is no visibly noticeable distortion, haze or flaws as detected by the naked eye at a distance of about 1 meter, preferably about 0.5 meters.

[0037] The term “vapor coating” or “vapor depositing” means applying a coating to a substrate surface from a vapor phase, for example, by evaporating and subsequently depositing onto the substrate surface a precursor material to the coating or the coating material itself. Exemplary vapor coating processes include, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD) and combinations thereof.

[0038] By using terms of orientation such as “atop”, “on”, “over,” “covering”, “uppermost”, “underlying” and the like for the location of various elements in the disclosed coated articles, we refer to the relative position of an element with respect to a horizontally-disposed, upwardly-facing substrate. However, unless otherwise indicated, it is not intended that the substrate or articles should have any particular orientation in space during or after manufacture, or in interpreting the claims.

[0039] As used herein, “radiation” refers to electromagnetic radiation unless otherwise specified.

[0040] As used herein, “transparent” refers to a material (e.g., film or layer) that absorbs less than 20% of light having wavelengths between 350 nm and 2500 nm.

[0041] The terms “about” or “approximately” with reference to a numerical value or a shape means + / - five percent of the numerical value or property or characteristic, but expressly includes the exact numerical value.

[0042] The term “substantially” with reference to a property or characteristic means that the property or characteristic is exhibited to a greater extent than the opposite of that property or characteristic is exhibited. For example, a substrate that is “substantially” transparent refers to a substrate that transmits more radiation (e.g., visible light) than it fails to transmit (e.g., absorbs and reflects). Thus, a substrate that transmits more than 50% of the visible light incident upon its surface is substantially transparent, but a substrate that transmits 50% or less of the visible light incident upon its surface is not substantially transparent.

[0043] As used in this specification and the appended embodiments, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference “a compound” includes a mixture of two or more compounds. As used in this specification and the appended embodiments, the term “or” is generally employed in its sense including “and / or” unless the content clearly dictates otherwise.

[0044] Unless otherwise indicated, all numbers expressing quantities or ingredients, measurement of properties and so forth used in the specification and embodiments are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached listing of embodiments can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings of the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claimed embodiments, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0045] By definition, the total weight percentages of all ingredients in a composition equals 100 weight percent.

[0046] Various exemplary embodiments of the disclosure will now be described. Exemplary embodiments of the present disclosure may take on various modifications and alterations without departing from the spirit and scope of the present disclosure. Accordingly, it is to be understood that the embodiments of the present disclosure are not to be limited to the following described exemplary embodiments but is to be controlled by the limitations set forth in the claims and any equivalents thereof.

[0047] In a first aspect, continuous method for making a nanostructured surface is provided. The method comprises:

[0048] placing a substrate on a cylindrical electrode in a vacuum vessel;

[0049] introducing at a first location in the vacuum vessel a first gaseous species capable of depositing a layer onto the substrate when formed into a plasma;

[0050] introducing at a second location in the vacuum vessel a second gaseous species capable of etching the substrate when formed into a plasma, wherein the first location is closer to an entrance of the vacuum vessel at an unwind side than to the second location;

[0051] generating a plasma from the first gaseous species and the second gaseous species between the cylindrical electrode and a counter-electrode;

[0052] rotating the cylindrical electrode to translate the substrate; and

[0053] exposing a major surface of the substrate to the plasma, wherein a layer is deposited on at least a portion of the major surface of the substrate and the substrate is etched, thereby forming nanostructures comprising at least one of nano-pillars, nano-columns, or continuous nano-walls comprising nano-pillars or nano-columns.

[0054] In a second aspect, an article is provided. The article is made according to the method of any embodiment of the first aspect, and has nano-pillars or nano-columns.

[0055] Referring to FIG.1, a flow chart is provided of such a continuous method of making a nanostructured surface. The flow chart includes the operation 110 of “Placing a substrate on a cylindrical electrode in a vacuum vessel”; the operation 120 of “Introducing at a first location in the vacuum vessel a first gaseous species capable of depositing a layer onto the substrate when formed into a plasma”; and the operation 130 of “Introducing at a second location in the vacuum vessel a second gaseous species capable of etching the substrate when formed into a plasma, wherein the first location is closer to an entrance of the vacuum vessel at an unwind side than to the second location”. The flow chart further includes the operation 140 of “Generating a plasma from the first gaseous species and the second gaseous species between the cylindrical electrode and a counter-electrode”; the operation 150 of “Rotating the cylindrical electrode to translate the substrate”; and the operation 160 of “Exposing a major surface of the substrate to the plasma, wherein a layer is deposited on at least a portion of the major surface of the substrate and the substrate is etched, thereby forming nanostructures comprising at least one of nano-pillars, nano- columns, or continuous nano-walls comprising nano-pillars or nano-columns”.

[0056] One suitable method for forming a nanostructured surface includes applying a thin, masking layer to a major surface of the substrate using plasma chemical vapor deposition. The masking layer is the reaction product of plasma chemical vapor deposition using a reactant gas that includes a compound selected from organosilicon compounds, metal alkyl compounds, metal isopropoxide compounds, metal oxide compounds, metal acetylacetonate compounds, metal halide compounds, and combinations thereof. Typically, the organosilicon compounds can include tetramethylsilane, trimethylsilane, hexamethyldisiloxane (HMDSO), tetraethylorthosilicate, or a polyhedral oligomeric silsesquioxane. In select cases, a preferred organosilicon compound is HMDSO. Useful metal alkyls can comprise trimethylaluminum, tributylaluminum, tributyltin, or tetramethyl gallium. Useful metal isopropoxides can comprise titanium isopropoxide, or zirconium isopropoxide. Useful metal acetylacetonates can comprise platinum acetylacetonates, or copper acetylacetonate. Useful metal halides can comprise titanium tetrachloride, or silicon tetrachloride. In certain embodiments, the first gaseous species (i.e., reactant gas) is mixed with a noble gas or an etchant gas.

[0057] Plasma chemical vapor deposition (or plasma-enhanced chemical vapor deposition) is a process by which plasmas, typically generated by radio-frequency discharge, are formed in the space between two electrodes when that space is filled with a reacting gas or gases. Plasma chemical vapor deposition is done under vacuum to reduce side reactions from unwanted species being present in the reacting chamber. The reacting gas or gases typically deposit thin solid films on a substrate. In the providedmethod, a masking layer is formed on the substrate using plasma chemical vapor deposition. Certain chemical species, when plasma deposited on a substrate in very short time form islands of material.

[0058] Typically, when reactant gases derived from relatively small organic or organometallic compounds are plasma chemical vapor deposited on a substrate, they initially form small islands of reacted material. Reaction conditions are adjusted (web speed, plasma discharge energy, time of exposure, etc.) so as to halt the deposition before a continuous layer of critical thickness occurs.

[0059] Forming a nanostructured surface further includes etching portions of the major surface not protected by the masking layer to form a nanostructure on the substrate. Typically, reactive ion etching is used for the etching. In one embodiment, the provided method can be carried out using a continuous roll- to-roll process referred to as “cylindrical reactive ion etching” (cylindrical RIE). Cylindrical RIE utilizes a rotating cylindrical electrode to provide anisotropically etched nanostructures on the surface of a substrate or article. In general, cylindrical RIE can be described as follows. A rotatable cylindrical electrode (“drum electrode”) powered by radio-frequency (RF) and a grounded counter-electrode are provided inside a vacuum vessel. The counter-electrode can comprise the vacuum vessel itself. An etchant gas is fed into the vacuum vessel, and a plasma is ignited and sustained between the drum electrode and the grounded counter-electrode. The individual islands typically have average dimensions of less than about 400 nm, less than about 200 nm, less than about 100 nm, less than about 50 nm or even less than about 20 nm.

[0060] A continuous substrate comprising a masking layer can then be wrapped around the circumference of the drum and the substrate can be etched in the direction normal to the plane of the substrate. The exposure time of the substrate can be controlled to obtain a predetermined etch depth of the resulting nanostructure. The process can be carried out at an operating pressure of approximately 10 mTorr. Cylindrical RIE is disclosed, for example, in PCT Pat. App. No. US / 2009 / 069662 (David et al.).

[0061] The etching gases (i.e., second gaseous species) can include, for example, oxygen, argon, chlorine, fluorine, a fluorocarbon (e.g., carbon tetrafluoride, perfluoromethane, perfluoroethane, perfluoropropane, nitrogen trifluoride, sulfur hexafluoride), nitrogen trifluoride, sulfur hexafluoride, methane, hydrochloric acid, and the like. In select cases, the second gaseous species comprises oxygen, a fluorocarbon, nitrogen trifluoride, sulfur hexafluoride, chlorine, hydrochloric acid, methane, or a combination thereof. Mixtures of gases may be used advantageously to enhance the etching process. Inert (e.g., noble) gases, particularly heavy gases such as argon, can be added to enhance the anisotropic etching process.

[0062] Additional details describing known methods of forming a nanostructured surface by depositing an etch mask material on a major surface of a substrate and reactive ion etching to anisotropically remove material in unmasked areas is disclosed, for example, in US Patent No.8,634,146 (David et al.).

[0063] Referring FIG.2A, current chamber 200a designs (referred to herein as Configuration A) for single-pass methods of forming a nanostructured surface introduce both the reactant gas for masking 210 and the etching gas(es) 220 a significant distance along the length of the down-web direction Wd of a process drum, which serves as the powered cylindrical electrode 230. This Configuration A further limitsthe available process window for nanostructure formation and dimensions because etch mask material will not be deposited on a substrate 240 at sufficient thickness for masking for about half of the residence time in the chamber 200a, thus, nanostructure is not formed at significant rates for about half of the residence time in the chamber 200a. This limits both throughput and achievable feature height in single- pass processing. Because the concurrent deposition of the etch mask material and etching of the underlying substrate must be balanced within the Configuration A, increasing the flow rate of the etch mask precursor to deposit etch mask material at web positions closer to the entrance of the process zone is not an effective solution because a continuous thin film will likely be formed, inhibiting nanostructure formation. Similarly, decreasing the line speed to try and achieve taller feature heights may also result in formation of a continuous thin film. For certain applications, control over nanostructure dimensions is critical to the intended product performance, and so it is desirable to both improve feature size control and increase the effective throughput for single-pass nanostructure processing.

[0064] Referring to FIG.2B, an alternative process gas configuration has been unexpectedly discovered to be effective at both increasing the throughput for single-pass nanostructure processing (relative to equivalent features achieved in the existing Configuration A of FIG.2A) and also allowing for additional control over nanostructure formations and dimensions. In this Configuration B chamber 200b, the precursor for the etch mask material 210 is introduced immediately at the start of the down-web direction Wd of the cylindrical electrode 230, and the etch mask material 210 is deposited in sufficient quantity such that nanostructures can be formed for the remainder of the residence time in the chamber 200b, meaning that the down-web length for etching following mask deposition is maximized. As such, the introduction of the etch mask material is more localized, and the nanostructures are not filled in or masked again after the initial deposition of the etch mask. In this Configuration B, the etchant gas 220 is introduced at the same location as previous configurations. It was unknown if a single-pass method could work without mixing the gases or by having the gases spaced apart within the chamber. Without wishing to be bound by theory, it is believed that because the relative flow rate for the etchant gas is much larger than the flow rate for the precursor used for the etch mask material, the input location for the etchant gas is likely less critical. This Configuration B effectively imitates a two-pass nanostructure process (i.e., deposition of etch mask material and subsequent etching) in a single-pass process, affording more control over nanostructure formation and dimensions. It is noted that just one plasma is formed from the combination of gases, but there will be a difference in species concentration throughout the chamber 200b. Additionally, the process window is generally larger because the deposition of etch mask material and etching of the substrate can be more easily separated and controlled. The new equipment design and process conditions allow for increased throughput and increased process window, particularly for substrates with relatively low etch rates where single-pass nanostructuring has previously not been possible.

[0065] Both Configuration A and Configuration B have numerous equipment and design features in common. For instance, each chamber 200a, 200b includes a pair of plates 201, 203 that separate a vacuum vessel (also referred to as an upper process chamber) 202 from an adjacent lower processchamber 204. Each chamber 200a, 200b includes a cylindrical electrode 230 located in the vacuum vessel 202. A roll-to-roll apparatus 250 is positioned primarily in the lower process chamber 204 including an unwind roll 252, a wind roll 254, and any optional tensioning rolls 256. For use, a substrate 240 is wound onto the unwind roll 252, fed past any tensioning rolls 256 present to direct the substrate 240 in between the two plates 201, 203 into the vacuum vessel 202, placed on an outer major surface of the cylindrical electrode 230, fed past any additional tensioning rolls 256 present to direct the substrate in between the two plates 201, 203 out of the vacuum vessel 202 and into the lower process chamber 204, then wound onto the wind roll 254. Accordingly, the term “unwind side” refers to the side of the lower process chamber 204 where the substrate 240 unwinds from an unwind roll 252 to enter the vacuum vessel 202. Each chamber 200a, 200b further includes a pump mechanism 205 configured to pull a vacuum down to a desired level at least within the vacuum vessel 202.

[0066] In some embodiments, the first location is within a sector from 0-90° as measured from the entrance 206 of the vacuum vessel 202 on the unwind side into a reaction zone Rz around the cylindrical electrode 230. Stated another way, the sector encompasses the first quarter of the surface area of the cylindrical electrode 230 (on which the substrate 240 is disposed).

[0067] FIG.3A is a generalized schematic side view of a Configuration B of a chamber for forming nanostructures, and FIG.3B is a rotated side view of Configuration B of FIG.3A, according to various exemplary embodiments disclosed herein. Referring to FIGS.3A-3B, many of the features shown in FIG.2B are left out for simplicity. As depicted, in some embodiments the second gaseous species 320 is introduced into the vacuum vessel 302 at the second location through a tube 360 comprising an array 362 of holes or slots 364, wherein the array 362 is substantially parallel to an axis of rotation of the cylindrical electrode 330. A size of the cross-section of the tube 360 is not limited. Optionally, a length L of the array 362 is equal to or greater than a width Ws of the substrate 340. In such cases, the cylindrical electrode 330 has a width of 15 centimeters to 2 meters.

[0068] In certain cases, the array is 362 located greater than 3 centimeters (cm) away from a surface of the cylindrical electrode 330, such as greater than 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, 13 cm, 14 cm, or greater than 15 cm away from a surface of the cylindrical electrode; and less than 30 cm away from a surface of the cylindrical electrode 330, less than 29 cm, 28 cm, 27 cm, 26 cm, 25 cm, 24 cm, 23 cm, 22 cm, 21 cm, 20 cm, 19 cm, 18 cm, 17 cm, 16 cm, 15 cm, 14 cm, 13 cm, 12 cm, 11 cm, or less than 10 cm away from a surface of the cylindrical electrode.

[0069] The first gaseous species is optionally introduced at a flow rate of less than one half, less than one fourth, less than one eighth, or less than one tenth, of the flow rate of the second gaseous species, in units of standard cubic centimeters per minute (sccm).

[0070] The nanostructured surface made by the method of the invention can have a nanostructured anisotropic surface. The nanostructured anisotropic surface typically can comprise nanoscale features having a height to width ratio or about 2:1 or greater; preferably about 5:1 or greater. In some embodiments, the height to width ratio can even be 50:1 or greater, 100:1 or greater, or 200:1 or greater. The nanostructured anisotropic surface can comprise nanofeatures such as, for example, one or more ofnano-pillars, nano-columns, or continuous nano-walls comprising nano-pillars or nano-columns. Typically, the nanofeatures have steep side walls that are substantially perpendicular to the boundary layer. In some embodiments, the nano-pillars or nano-columns are substantially co-planar. Preferably, an average height of the nano-pillars or nano-columns is greater than 50 nanometers (nm), greater than 75 nm, or greater than 100 nm. Average height can be determined by taking a scanning electron microscopy (SEM) image, measuring the height of the nanofeatures in at least three places, and taking the average of the height measurements. In some cases, the nanofeatures have at least one dimension of 500 nm or less.

[0071] In some embodiments, the majority of the nanofeatures can be capped with mask material. The mask material can have a thickness from about 3 nm to about 150 nm or from about 5 nm to about 50 nm or from about 10 nm to about 30 nm.

[0072] Referring to FIG.4, a generalized schematic cross-sectional view is provided of an exemplary nanostructured article 400 including a substrate 420 comprising a major surface 421 that has a nanostructured anisotropic surface 423.

[0073] Referring to FIG.5, in some embodiments, a nanostructured article 500 includes a substrate 520 comprising a major surface 521 that has a nanostructured anisotropic surface 523. The nanostructures are overlaid with a layer 530 that is a pressure sensitive adhesive or a thermoset material. In select embodiments, a force required to peel a pressure sensitive adhesive away from the nanostructured substrate is greater than 15 Newtons per inch (N / in), measured according to the 232 Tape Peel Test described in the Examples below.

[0074] Referring to FIG.6, in some embodiments, a nanostructured article 600 is provided in a form of a roll. A roll may be formed by winding up a nanostructured substrate 620 (and any optional additional layers). This may be performed during the nanostructuring process or afterwards, as convenient.

[0075] Some suitable materials for each of the first and second aspects are described in detail below. Substrates

[0076] Articles according to the present application include a substrate, which is not particularly limited. For instance, in some cases the substrate comprises a (co)polymeric material. In certain embodiments, the substrate includes a (co)polymeric material and the (co)polymeric material comprises a (co)polymer selected from the group consisting of a poly(methyl methacrylate), a poly(ethylene terephthalate), a polycarbonate, a cellulose, a triacetate, a polyamide, a polyimide, a fluoropolymer, a polyolefin, a siloxane (co)polymer, a cyclic olefin (co)polymer, a polyurethane, and combinations thereof. For certain applications, it is advantageous to use a substrate that comprises a transparent (co)polymeric material.

[0077] Suitable thicknesses of a substrate are 0.5 micrometers or greater, 0.8 micrometers, 1.0 micrometers, 1.5 micrometers, 2.0 micrometers, 2.5 micrometers, 3.0 micrometers, 3.5 micrometers, 4.0 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, or 8 micrometers or greater; and 10 micrometers or less, 9 micrometers, 8 micrometers, 7 micrometers, 6 micrometers, 5 micrometers, 4 micrometers, or 3 micrometers or less. Stated another way, in some cases a boundary layer has a thickness of between 0.5 micrometers and 10 micrometers.Pressure Sensitive Adhesives

[0078] In some embodiments, an article according to the present disclosure may include a pressure sensitive adhesive disposed on the nanostructured surface of the substrate.

[0079] Classes of suitable pressure sensitive adhesives include acrylics, tackified rubber, tackified synthetic rubber, ethylene vinyl acetate and the like. Suitable acrylic adhesives are disclosed, for example, in U.S. Pat. Nos.3,239,478 (Harlan); 3,935,338 (Robertson); 5,169,727 (Boardman); 4,952,650 (Young et al.) and 4,181,752 (Martens et al.), incorporated herein by reference.

[0080] In select embodiments, the adhesive is optically clear, which means that the adhesive has both transparency and clarity (e.g., low haze). In certain embodiments, an optically clear adhesive (OCA) is selected from an acrylate, a polyurethane, a polyolefin (such as a polyisobutylene (PIB)), a silicone, or a combination thereof. Illustrative OCAs include those described in International Pub. No. WO 2008 / 128073 (Everaerts et al.) relating to antistatic optically clear pressure sensitive adhesives, U.S. Pat. App. Pub. Nos. US 2009 / 089137 (Sherman et al.) relating to stretch releasing OCA, US 2009 / 0087629 (Everaerts et al.) relating to indium tin oxide compatible OCA, US 2010 / 0028564 (Cheng et al.) relating to antistatic optical constructions having optically transmissive adhesive, US 2010 / 0040842 (Everaerts et al.) relating to adhesives compatible with corrosion sensitive layers, US 2011 / 0126968 (Dolezal et al.) relating to optically clear stretch release adhesive tape, and U.S. Pat. No.8,557,378 (Yamanaka et al.) relating to stretch release adhesive tapes. Suitable OCAs include acrylic optically clear pressure sensitive adhesives such as, for example, 3M OCA 8146, 8211, 8212, 8213, 8214, and 8215, each available from 3M Company, St. Paul, MN.

[0081] In some cases, some of the (optional) pressure sensitive adhesive may interpenetrate the nanofeatures of the nanostructured anisotropic surface of the substrate. In other cases, the adhesive may only come into contact with the tops of the nanofeatures of the nanostructured anisotropic surface of the substrate. Exemplary thicknesses of a layer of a pressure-sensitive adhesive may be in the range from about 0.05 to about 100 micrometers. Thermoset Material

[0082] In some embodiments, an article according to the present disclosure may include a thermoset material disposed on the nanostructured surface of the substrate. As used herein, “thermoset” refers to a polymer that permanently sets upon curing and does not flow upon subsequent heating. Thermoset polymers are typically crosslinked polymers. The thermoset material may be formed, for instance, via crosslinking of a monomer or oligomer. Examples of monomers or oligomers for use in such a layer includes (meth)acrylates. Some suitable polymeric materials for the thermoset material include for instance and without limitation, crosslinked (meth)acrylic polymers, urethane polymers, vinyl polymers, epoxy polymers, phenolic polymers, cyanate esters, polyimides, bismaleimides, or combinations thereof. The thermoset material may also contain adhesion-promoting additives.

[0083] In some cases, some of the (optional) thermoset material may interpenetrate the nanofeatures of the nanostructured anisotropic surface of the substrate. In other cases, the thermoset material may only come into contact with the tops of the nanofeatures of the nanostructured anisotropic surface of the substrate. Exemplary thicknesses of a layer of a thermoset material may be in the range from about 0.05 to about 100 micrometers.

[0084] Listing of Exemplary Embodiments

[0085] In a first embodiment, the present disclosure provides a continuous method for making a nanostructured surface. The method comprises placing a substrate on a cylindrical electrode in a vacuum vessel; introducing at a first location in the vacuum vessel a first gaseous species capable of depositing a layer onto the substrate when formed into a plasma; introducing at a second location in the vacuum vessel a second gaseous species capable of etching the substrate when formed into a plasma, wherein the first location is closer to an entrance of the vacuum vessel at an unwind side than to the second location; generating a plasma from the first gaseous species and the second gaseous species between the cylindrical electrode and a counter-electrode; rotating the cylindrical electrode to translate the substrate; and exposing a major surface of the substrate to the plasma, wherein a layer is deposited on at least a portion of the major surface of the substrate and the substrate is etched, thereby forming nanostructures comprising at least one of nano-pillars, nano-columns, or continuous nano-walls comprising nano-pillars or nano-columns.

[0086] In a second embodiment, the present disclosure provides a method according to the first embodiment, wherein the first location is within a sector from 0-90° as measured from the entrance of the vacuum vessel into a reaction zone around the cylindrical electrode.

[0087] In a third embodiment, the present disclosure provides a method according to the first embodiment, wherein the second gaseous species is introduced at the second location through a tube comprising an array of holes or slots, wherein the array is substantially parallel to an axis of rotation of the cylindrical electrode.

[0088] In a fourth embodiment, the present disclosure provides a method according to the third embodiment, wherein a length of the array is equal to or greater than a width of the substrate.

[0089] In a fifth embodiment, the present disclosure provides a method according to the third embodiment, wherein the array is located greater than 3 centimeters (cm) and less than 30 cm away from a surface of the cylindrical electrode.

[0090] In a sixth embodiment, the present disclosure provides a method according to any of the first through fifth embodiments, wherein the first gaseous species is introduced at a flow rate of less than one half, less than one fourth, less than one eighth, or less than one tenth, of the flow rate of the second gaseous species, in units of standard cubic centimeters per minute (sccm).

[0091] In a seventh embodiment, the present disclosure provides a method according to any of the first through sixth embodiments, wherein the first gaseous species is mixed with a noble gas or an etchant gas.

[0092] In an eighth embodiment, the present disclosure provides a method according to any of the first through seventh embodiments, wherein the substrate comprises a (co)polymeric material.

[0093] In a ninth embodiment, the present disclosure provides a method according to the eighth embodiment, wherein the (co)polymeric material comprises a (co)polymer selected from the group consisting of a poly(methyl methacrylate), a poly(ethylene terephthalate), a polycarbonate, a cellulose, a triacetate, a polyamide, a polyimide, a fluoropolymer, a polyolefin, a siloxane (co)polymer, a cyclic olefin (co)polymer, a polyurethane, and combinations thereof.

[0094] In a tenth embodiment, the present disclosure provides a method according to any of the first through ninth embodiments, wherein the substrate comprises a transparent (co)polymeric material.

[0095] In an eleventh embodiment, the present disclosure provides a method according to any of the first through tenth embodiments, wherein the first gaseous species comprises a compound selected from the group consisting of organosilicon compounds, metal alkyl compounds, metal isopropoxide compounds, metal oxide compounds, metal acetylacetonate compounds, metal halide compounds, and combinations thereof.

[0096] In a twelfth embodiment, the present disclosure provides a method according to the eleventh embodiment, wherein the organosilicon compounds comprise tetramethylsilane, trimethylsilane, hexamethyldisiloxane, tetraethylorthosilicate, a polyhedral oligomeric silsesquioxane, or a combination thereof.

[0097] In a thirteenth embodiment, the present disclosure provides a method according to any of the first through tenth embodiments, wherein the second gaseous species comprises oxygen, a fluorocarbon, nitrogen trifluoride, sulfur hexafluoride, chlorine, hydrochloric acid, methane, or a combination thereof.

[0098] In a fourteenth embodiment, the present disclosure provides an article made according to the method of any of the first through thirteenth embodiments, having nano-pillars or nano-columns.

[0099] In a fifteenth embodiment, the present disclosure provides an article according to the fourteenth embodiment, wherein an average height of the nano-pillars or nano-columns is greater than 50 nanometers (nm), greater than 75 nm, or greater than 100 nm.

[0100] In a sixteenth embodiment, the present disclosure provides an article according to the fourteenth or fifteenth embodiment, wherein the nano-pillars or nano-columns are substantially co-planar.

[0101] In a seventeenth embodiment, the present disclosure provides an article according to any of the fourteenth through sixteenth embodiments, provided in a form of a roll.

[0102] In an eighteenth embodiment, the present disclosure provides an article according to any of the fourteenth through seventeenth embodiments, wherein the nanostructures are overlaid with a pressure sensitive adhesive or a thermoset material.

[0103] In a nineteenth embodiment, the present disclosure provides an article according to the eighteenth embodiment, wherein a force required to peel the pressure sensitive adhesive away from the nanostructured substrate is greater than 15 N / in, measured according to the 232 Tape Peel Test.EXAMPLES

[0104] Unless otherwise noted or readily apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. DESIGNATION DESCRIPTION SOURCE HMDSO hexamethyldisiloxane (98%) Gelest, Morrisville, PA oxygen oxygen (ultra-high purity grade) Airgas, St. Paul, MN polyimide DuPont Kapton HN polyimide film DuPont Teijin Films, Chester, VA (500HN), 500-gauge thickness (8-inch width) THV THV500 (tetrafluoroethylene, 3M Company, St. Paul, MN hexafluoropropylene, and vinylidene fluoride) film, 10-mil thickness polyurethane polyurethane film with PET backing 3M Company, St. Paul, MN PET heat-stabilized polyester film (ST580), DuPont Teijin Films, Chester, VA 500-gauge thickness, single-side primed, (12 – 16-inch width) 3M 232 tape 3M High Performance Masking Tape 3M Company, St. Paul, MN (232), (1-inch width) 3M 5498 tape 3M PTFE Film Tape (5498), (0.5-inch 3M Company, St. Paul, MN width) 3M 898 tape Scotch Filament Tape (898), (0.5-inch 3M Company, St. Paul, MN width) 3M 410M tape 3M Double Coated Paper Tape (410M), 3M Company, St. Paul, MN (1-inch width)

[0105] General Method for Roll-to-Roll (R2R) Nanostructuring

[0106] The process for nanostructuring was performed in a custom-built parallel plate capacitively coupled plasma reactor. The chamber has a central cylindrical powered electrode with a surface area of about 1.70 m2. After loading the rolled substrate into the chamber, the reactor chamber was pumped down to a base pressure of less than 1 mtorr. Process gas was introduced into the chamber at the flow rates detailed in the tables below. Plasma-enhanced chemical vapor deposition / reactive ion etching was performed by coupling RF power into the reactor at a frequency of 13.56 MHz and an applied power detailed in the tables below. The treatment time was controlled by translating the film samples through the reaction zone at speeds detailed in the tables below. The operating pressure during treatment is detailed in the tables below. Following the treatment(s), the process gas flow, applied power, and film translation were stopped, and the chamber was returned to atmospheric pressure. Additional information regarding materials and processes for applying cylindrical RIE and further details around the reactor used can be found in US8460568 B2.

[0107] Wavelength Dispersive X-ray Fluorescence (WDXRF) Spectroscopy

[0108] Wavelength dispersive X-ray fluorescence measurements were collected with a Supermini200 WDXRF instrument from Rigaku Corporation (Woodlands, TX). Samples were measured in vacuum using the manufacturer-standard settings to measure the net intensity of the silicon k-alpha peak.

[0109] Scanning Electron Microscopy (SEM) Imaging

[0110] Samples were mounted on aluminum examination stubs and coated with AuPd by DC sputtering in a Denton Vacuum Desk IV coater to ensure conductivity. Examinations were performed in a Hitachi S4700 Field Emission Scanning Electron Microscope. Where applicable, feature dimensions were measured in ImageJ using the reference scale bar generated by the S4700 microscope.

[0111] 3M 232 Tape Peel

[0112] 3M 232 tape (1-inch width) was laminated to the surface of the sample with a 4.5-lb (2.04 kg) hand roller (steel core with a Shore scale A 80 durometer silicone rubber cover) at an angle of about 90 degrees – the end of the tape was folded over and stapled to ensure the peel fixture would not slip. The sample was then mounted to the stage of an Imass SP-2100 with 3M 410M double-sided masking tape and using a 3M PA1 - B hand applicator. The tape was peeled at 6 in / min (15.24 cm / min) at an angle of about 180 degrees for 6 seconds (first second of data is ignored) – the average value (in Newtons per inch (N / in) over 5 seconds is reported. For 3M 232 tape, cohesive failure of the adhesive is observed at values over about 24.5 N / in.

[0113] 3M 5498 Tape Peel

[0114] 3M 5498 tape (0.5-inch width) was laminated to the surface of the sample with a 4.5-lb (2.04 kg) hand roller (steel core with a Shore scale A 80 durometer silicone rubber cover) roller at an angle of about 90 degrees. 3M 898 tape (0.5-inch width) was then laminated over the top of the 5498 tape with a 4.5-lb (2.04 kg) hand roller (steel core with a Shore scale A 80 durometer silicone rubber cover) at an angle of about 90 degrees – this is to provide more rigidity to the 5498 tape and ensure no stretching of the backing of the 5498 tape occurs. The end of the tape laminate was folded over and stapled to ensure the peel fixture would not slip. The sample was then mounted to the stage of an Imass SP-2100 with 3M 410M double-sided masking tape and using a 3M PA1 - B hand applicator. The tape was peeled at 6 in / min (15.24 cm / min) at an angle of about 180 degrees for 6 seconds (first second of data is ignored) – the average value (N / in) over 5 seconds is reported. For 3M 5498 tape, cohesive failure of the adhesive is observed at values over about 45 N / in.

[0115] Comparative Examples (Configuration A)

[0116] For creating random nanostructure, a controlling variable is the exposure (or integrated flux) to a precursor for the etch mask material (in this case HMDSO), which is defined as the HMDSO flow rate in standard cubic centimeters per minute (sccm) multiplied by the residence time in seconds (sec). Generally, higher HMDSO exposure values translate to earlier (down-web) mask deposition and increased time (down-web length) for etching (and thus formation of nanostructures). Reducing the line speed will increase HMDSO exposure values (nanostructure height, adhesion, etc.) but will correspondingly reduce throughput. Increasing the HMDSO flow will increase HMDSO exposure values, but, above a certain threshold, a continuous film of a critical thickness will be deposited such that nonanostructures will be formed. To simplify understanding, many of the example data sets are presented as a function of the HMDSO exposure values.

[0117] Comparative Example Set 1: Nanostructures on polyimide film with Configuration A

[0118] Comparative Example Set 1 (CE SET 1) comprises random nanostructures on a substrate that is polyimide film, varying the HMDSO flow rate and line speed. Detailed process conditions can be found in Table 1, noting that for all samples the O2gas flow rate was 750 sccm.

[0119] The 232 peel force and 5498 peel force for CE SET 1 are shown in Table 2. The peel force response was linear with HMDSO exposure (for the range of conditions investigated), possibly approaching a limit of about 35 N / in above 1000 (sccm*sec).

[0120] Selected samples were examined with scanning electron microscopy (SEM) to determine the average nanostructure height. The average nanostructure height for CEX SET 1 is shown in Table 2. The height of the nanostructure was linear with HMDSO exposure (for the range of conditions investigated).

[0121] For samples where the nanostructure height was measured, the 232 peel force and 5498 peel force versus nanostructure height for CEX SET 1 was determined to be proportional to the feature height. Table 1. ID HMDSO Power (W) Line Speed Residence HMDSO Pressure Flow (fpm) Time (sec) INT Flux (mtorr) (sccm) (sccm*sec) CE-1.1 14 7500 10 30 420 6.7 CE-1.2 14 7500 15 20 280 6.9 CE-1.3 14 7500 20 15 210 7.1 CE-1.4 14 7500 24 12.5 175 7.2 CE-1.5 14 7500 30 10 140 7.3 CE-1.6 14 9000 10 30 420 7.4 CE-1.7 14 9000 15 20 280 7.6 CE-1.8 14 9000 20 15 210 7.7 CE-1.9 14 9000 24 12.5 175 7.9 CE-1.10 14 9000 30 10 140 8.0 CE-1.11 20 7500 10 30 600 7.7 CE-1.12 20 7500 15 20 400 7.9 CE-1.13 20 7500 20 15 300 8.1 CE-1.14 20 7500 24 12.5 250 8.2 CE-1.15 20 7500 30 10 200 8.4 CE-1.16 20 9000 10 30 600 8.4CE-1.17 20 9000 15 20 400 8.6 CE-1.18 20 9000 20 15 300 8.8 CE-1.19 20 9000 24 12.5 250 9.0 CE-1.20 20 9000 30 10 200 9.2 CE-1.21 17 9000 10 30 510 8.8 CE-1.22 17 9000 15 20 340 9.0 CE-1.23 17 9000 20 15 255 9.1 CE-1.24 17 9000 24 12.5 213 9.3 CE-1.25 17 9000 30 10 170 9.4 CE-1.26 26 9000 10 30 780 9.7 CE-1.27 26 9000 15 20 520 9.9 CE-1.28 26 9000 20 15 390 10.0 CE-1.29 26 9000 24 12.5 325 10.2 CE-1.30 26 9000 30 10 260 10.4 Table 2. ID Si k-alpha 232 Tape 232 Tape 5498 Tape 5498 Tape Ave Peel Ave Peel Stdev Peel Ave Peel Stdev Nanostructure (N / in) (N / in) height (nm) CE-1.1 0.123 20.99 0.31 57 CE-1.2 0.116 16.94 0.39 31 CE-1.3 0.060 14.88 0.40 15.31 0.53 27 CE-1.4 0.052 13.77 0.42 14.05 0.06 25 CE-1.5 0.048 12.79 0.49 36 CE-1.6 0.116 20.10 0.64 20.32 0.58 45 CE-1.7 0.088 16.08 0.43 15.67 0.61 39 CE-1.8 0.050 13.31 0.27 15.78 0.30 CE-1.9 0.064 12.37 0.26 25 CE-1.10 0.037 12.03 0.10 13.65 0.44 CE-1.11 0.209 24.06 0.35 78 CE-1.12 0.110 23.18 0.36 77 CE-1.13 0.058 20.48 0.21 63 CE-1.14 0.058 17.51 0.39 41 CE-1.15 0.057 14.75 0.23 36 CE-1.16 0.181 23.61 0.51 25.25 0.38 76 CE-1.17 0.115 22.25 0.14 19.78 0.34 CE-1.18 0.080 19.56 0.13 17.97 0.39 39CE-1.19 0.070 17.25 0.27 33 CE-1.20 0.060 15.35 0.18 16.04 0.11 25 CE-1.21 0.161 22.84 0.30 22.32 0.41 CE-1.22 0.096 20.07 0.17 CE-1.23 0.074 17.81 0.22 CE-1.24 0.078 16.61 0.36 CE-1.25 0.049 14.92 0.31 CE-1.26 0.296 23.54 0.19 30.18 1.02 CE-1.27 0.187 23.85 0.11 24.99 0.27 CE-1.28 0.141 22.18 0.26 20.12 0.21 CE-1.29 0.087 19.32 0.16 CE-1.30 0.080 16.26 0.32 15.62 0.35

[0122] It is informative to run a “drum-stop” sample where the process is abruptly stopped, and the down-web formation of the nanostructure was investigated. The rate of Si (mask deposition) showed maximum localized rates of deposition near the HMDSO manifolds (about 15 and 45 inches). The tape peel response only started to increase after the first maximum in the rate of Si (mask) deposition – i.e., adhesion starts to increase only after the nanostructure height begins to increase after significant amounts of mask material have been deposited. With this understanding, there is no nanostructure (of significant height) being formed for at least the beginning third of the residence time in the system, thus the motivation for the alternative process gas configuration. Additionally, the second localized rate of Si (mask) deposition from the second manifold may slow the process of nanostructure formation as some material may be deposited at the bottom of the structures which would need to be removed (sputtered) before etching to increase nanostructure height can continue.

[0123] Comparative Example Set 2: Nanostructures on THV film with Configuration A

[0124] Comparative Example Set 2 (CE SET 2) comprises random nanostructures on a substrate that is THV film, varying the HMDSO flow rate and line speed. Detailed process conditions can be found in Table 3, noting that for all samples the O2gas flow rate was 750 sccm and the power was 9000 Watts (W).

[0125] Note that the HMDSO exposure values are higher relative to the other example sets – higher HMDSO flow rates are required when nanostructuring THV because the fluorine etch products will consume a portion of the silicon species.

[0126] The 232 peel force and 5498 peel force for CE SET 2 are shown in Table 4. The peel force response was linear with HMDSO exposure (for the range of conditions investigated), possibly approaching a limit of about 25 N / in above 1000 (sccm*sec). The peel force response showed an optimal value of about 20 N / in at about 800 (sccm*sec) and then started to decrease. This is a result ofapproaching the continuous film limit where a critical thickness is reached such that no substantial etching to form nanostructure occurs.

[0127] Selected samples were examined with SEM to determine the average nanostructure height. The average nanostructure height for CE SET 2 is shown in Table 4. The height of the nanostructure was linear with HMDSO exposure (for the range of conditions investigated). Note that the feature height as a function of HMDSO exposure for CE SET 2 (THV) is higher than CE SET 1 (polyimide) because the etch rate of THV is higher, which is a controlling variable for the nanostructuring process space in addition to HMDSO exposure.

[0128] For samples where the nanostructure height was measured, the 232 peel force and 5498 peel force versus nanostructure height for CE SET 2 was determined to be proportional to the feature height.

[0129] The rate of Si (mask deposition) again showed maximum localized rates of deposition near the HMDSO manifolds (about 15 and 45 inches), and an increase in adhesion that is limited to a relatively short portion of the down-web length of the chamber. Table 3. ID HMDSO Line Speed Residence HMDSO Pressure Flow (fpm) Time (sec) INT Flux (mtorr) (sccm) (sccm*sec) CE-2.1 37 10 30 1110 11 CE-2.2 37 15 20 740 11.4 CE-2.3 37 20 15 555 11.6 CE-2.4 37 24 12.5 463 11.8 CE-2.5 37 30 10 370 11.8 CE-2.6 45 10 30 1350 11.6 CE-2.7 45 15 20 900 11.9 CE-2.8 45 20 15 675 12 CE-2.9 45 24 12.5 563 12.1 CE-2.10 45 30 10 450 12.3 CE-2.11 53 10 30 1590 12 CE-2.12 53 15 20 1060 12.2 CE-2.13 53 20 15 795 12.4 CE-2.14 53 24 12.5 663 12.5 CE-2.15 53 30 10 530 12.8Table 4. ID Si k-alpha 232 Tape 232 Tape 5498 Tape 5498 Tape Ave Peel Ave Peel Stdev Peel Ave Peel Stdev Nanostructure (N / in) (N / in) height (nm) CE-2.1 0.355 23.80 0.27 CE-2.2 0.272 21.71 0.34 CE-2.3 0.256 15.41 0.83 CE-2.4 0.250 11.70 0.48 CE-2.5 0.241 11.06 0.32 8.13 0.20 189 CE-2.6 0.452 22.92 0.59 22.27 0.47 106 CE-2.7 0.341 22.36 0.54 20.06 0.71 84 CE-2.8 0.297 19.70 0.78 16.61 0.67 93 CE-2.9 0.265 18.64 0.49 11.97 0.08 35 CE-2.10 0.251 12.32 0.29 8.77 0.08 CE-2.11 0.619 15.78 1.32 CE-2.12 0.475 17.88 1.32 CE-2.13 0.353 18.43 1.06 CE-2.14 0.337 15.57 0.93 CE-2.15 0.341 12.07 0.09

[0130] Comparative Example Set 3: Nanostructures on polyurethane film with Configuration A

[0131] Comparative Example Set 3 (CE SET 3) comprises random nanostructure on a substrate that is a polyurethane film, varying the HMDSO flow rate and line speed. Detailed process conditions can be found in Table 5, noting that for all samples the O2gas flow rate was 750 sccm, the HMDSO gas flow rate was 20 sccm, and the power was 7500 W.

[0132] The 232 peel force for CE SET 3 are shown in Table 5. The peel force response was linear with HMDSO exposure, but the rate of adhesion increase was low in comparison to the previous comparative example sets. This can be explained by the relatively low etch rate of polyurethane films – a longer residence time is required to etch nanostructure to a significant height. Reducing the line speed to compensate is not only a problem for throughput, but slower line speeds also can result in issues with thermal distortion of the web, especially for thermally-sensitive substrates such as polyurethane. Additionally, if the line speed is reduced below some critical value, the continuous film limit will likely be reached (with localized deposition in proximity to the gas manifolds) – this problem can also not be solved simply be reducing the HMDSO flow rate, because the flow cannot be reliably controlled below about 10 sccm.Table 5. ID Line Residence HMDSO Pressure Si k-alpha 232 232 Speed Time (sec) INT Flux (mtorr) Tape Tape (fpm) (sccm*sec) Peel Peel Ave Stdev (N / in) CE-3.1 5 60 1200 7.0 0.479 15.09 N / A CE-3.2 10 30 600 7.0 0.242 12.42 0.5 CE-3.3 15 20 400 7.3 0.146 10.38 0.2

[0133] Comparative Example Set 4: Nanostructures on PET film with Configuration A

[0134] Comparative Example Set 4 (CE SET 4) comprises random nanostructures on a substrate that is a PET film, varying the HMDSO flow rate and line speed. Detailed process conditions can be found in Table 6, noting that for all samples the O2gas flow rate was 750 sccm. The 232 peel force for CE SET 4 are shown in Table 7. The peel force response was linear with HMDSO exposure until the cohesive limit of the tape was reached (25 N / in) at about 300 (sccm*sec). The peel force response with 5498 tape was not investigated for these samples. Table 6. ID HMDSO Power (W) Line Speed Residence HMDSO Pressure Flow (fpm) Time (sec) INT Flux (mtorr) (sccm) (sccm*sec) CE-4.1 15 7500 7.5 40 600 7.4 CE-4.2 15 7500 10.0 30 450 7.8 CE-4.3 15 7500 20.0 15 225 8 CE-4.4 15 7500 24.0 12.5 188 8.2 CE-4.5 15 7500 30.0 10 150 8.3 CE-4.6 15 9000 10.0 30 450 8.3 CE-4.7 15 9000 15.0 20 300 8.4 CE-4.8 15 9000 20.0 15 225 8.5 CE-4.9 15 9000 24.0 12.5 188 8.5 CE-4.10 15 9000 30.0 10 150 8.6 CE-4.11 20 7500 7.5 40 800 8.3 CE-4.12 20 7500 10.0 30 600 8.4 CE-4.13 20 7500 20.0 15 300 8.6 CE-4.14 20 7500 24.0 12.5 250 8.8 CE-4.15 20 7500 30.0 10 200 8.9CE-4.16 20 9000 7.5 40 800 8.8 CE-4.17 20 9000 10.0 30 600 9.1 CE-4.18 20 9000 20.0 15 300 9.3 CE-4.19 20 9000 24.0 12.5 250 9.4 CE-4.20 20 9000 30.0 10 200 9.4 CE-4.21 20 11000 10.0 30 600 9.3 CE-4.22 20 11000 15.0 20 400 9.4 CE-4.23 20 11000 20.0 15 300 9.4 CE-4.24 20 11000 24.0 12.5 250 9.5 CE-4.25 20 11000 30.0 10 200 9.5 Table 7. ID 232 Tape 232 Tape Peel Ave Peel Stdev (N / in) CE-4.1 24.01 0.20 CE-4.2 25.83 0.23 CE-4.3 22.36 0.13 CE-4.4 17.67 0.27 CE-4.5 14.13 0.16 CE-4.6 24.69 0.31 CE-4.7 23.52 0.37 CE-4.8 19.61 0.37 CE-4.9 16.02 0.62 CE-4.10 13.14 0.24 CE-4.11 24.59 0.28 CE-4.12 25.43 0.22 CE-4.13 22.21 0.32 CE-4.14 18.41 0.36 CE-4.15 14.24 0.39 CE-4.16 23.94 0.35 CE-4.17 25.00 0.10 CE-4.18 21.93 0.37 CE-4.19 22.54 0.40 CE-4.20 18.57 0.34 CE-4.21 25.36 0.34 CE-4.22 24.90 0.30CE-4.23 21.73 0.29 CE-4.24 17.24 0.49 CE-4.25 16.31 0.41 Examples (Configuration B)

[0135] Example Set 1: Nanostructures on polyimide film with Configuration B

[0136] Example Set 1 (EX SET 1) comprises random nanostructure on a substrate that is a polyimide film, varying the HMDSO flow rate and line speed, with HMDSO delivered through the alternative manifold configuration (Configuration B). Detailed process conditions can be found in Table 8, noting that for all samples the O2gas flow rate was 750 sccm.

[0137] The 232 peel force and 5498 peel force for EX SET 1 are shown in Table 9. The peel force response was linear with HMDSO exposure (for the range of conditions investigated), approaching the cohesive failure of 5498 tape at about 600 (sccm*sec).

[0138] With Configuration B, there was not only an increase in the rate of adhesion increase with HMDSO exposure, but it was also possible to achieve higher adhesion to the surface working within other system constraints as discussed previously (limited down-web length, mass flow controller limitations, etc.).

[0139] Selected samples were examined with scanning electron microscopy (SEM) to determine the average nanostructure height. The average nanostructure height for EX SET 1 is shown in Table 9. The height of the nanostructures was linear with HMDSO exposure (for the range of conditions investigated). The nanostructure height versus HMDSO exposure for CE SET 1 (i.e., white circles) and EX SET 1 (shaded circles) comparing Configuration A and B for polyimide is shown in FIG.9. Following from the adhesion results, it is possible to achieve taller nanostructures with Configuration B working within other system constraints as discussed previously (limited down-web length, mass flow controller limitations, etc.). Referring to FIGS.7A-7B and 8A-8B, SEM images are provided of cross-sections of portions of samples of CE-1.18 (FIG.7A), EX-1.19 (FIG.7B), CE-1.16 (FIG.8A) and EX-1.17 (FIG.8B). FIGS. 7A and 7B show the difference in average nanostructure height at an HMDSO exposure of 300 sccm*sec. Referring to FIG.7A, the average nanostructure height Hn for Configuration A was 39 nm. Referring to FIG.7B, the average nanostructure height Hn for Configuration B was 68 nm. FIGS.8A and 8B show the difference in average nanostructure height at an HMDSO exposure of 600 sccm*sec. Referring to FIG.8A, the average nanostructure height Hn for Configuration A was 76 nm. Referring to FIG.8B, the average nanostructure height Hn for Configuration B was 153 nm.

[0140] For samples where the nanostructure height was measured, the 5498 peel force versus feature height for EX SET 1 was determined to be proportional to the feature height, as expected. The 5498 tape peel was proportional to the feature height irrespective of the gas flow configuration, which suggests physical / surface-area mechanisms (including nanostructure height) are the dominant factor in promoting surface adhesion.

[0141] A “drum-stop” sample was also run with Configuration B – the rate of Si (mask deposition) showed a maximum rate of deposition near the alternate HMDSO manifold at about 9 inches. Again the tape peel response only started to increase after the first maximum in the rate of Si (mask) deposition – i.e., adhesion starts to increase only after the nanostructure height begins to increase after significant amounts of mask material have been deposited. In this configuration, the down-web length for etching (creating nanostructure) following mask deposition is maximized. Table 8. ID HMDSO Power (W) Line Speed Residence HMDSO Pressure Flow (fpm) Time (sec) INT Flux (mtorr) (sccm) (sccm*sec) EX-1.1 14 7500 10 30 420 7.3 EX-1.2 14 7500 15 20 280 7.4 EX-1.3 14 7500 20 15 210 7.6 EX-1.4 14 7500 24 12.5 175 7.2 EX-1.5 14 7500 30 10 140 7.3 EX-1.6 14 9000 10 30 420 7.9 EX-1.7 14 9000 15 20 280 8.1 EX-1.8 14 9000 20 15 210 8.3 EX-1.9 14 9000 24 12.5 175 8.4 EX-1.10 14 9000 30 10 140 8.5 EX-1.11 20 7500 10 30 600 8.1 EX-1.12 20 7500 15 20 400 8.1 EX-1.13 20 7500 20 15 300 8.4 EX-1.14 20 7500 24 12.5 250 8.6 EX-1.15 20 7500 30 10 200 8.7 EX-1.16 20 9000 30 10 200 9.0 EX-1.17 20 9000 10 30 600 8.2 EX-1.18 20 9000 15 20 400 8.5 EX-1.19 20 9000 20 15 300 8.7 EX-1.20 20 9000 24 12.5 250 8.9 EX-1.21 20 9000 30 10 200 9.1 EX-1.22 26 9000 10 30 780 7.6 EX-1.23 26 9000 15 20 520 8.0 EX-1.24 26 9000 20 15 390 8.2 EX-1.25 26 9000 24 12.5 325 8.3 EX-1.26 26 9000 30 10 260 8.5EX-1.27 32 9000 10 30 960 7.9 EX-1.28 32 9000 20 15 480 8.4 Table 9. ID Si k-alpha 232 Tape 232 Tape 5498 Tape 5498 Tape Ave Peel Ave Peel Stdev Peel Ave Peel Stdev Nanostructure (N / in) (N / in) height (nm) EX-1.1 0.137 23.89 0.21 EX-1.2 0.074 20.31 0.19 75 EX-1.3 0.060 17.15 0.25 56 EX-1.4 0.051 14.58 0.08 33 EX-1.5 0.067 14.99 0.37 38 EX-1.6 0.133 23.53 0.32 27.51 0.09 94 EX-1.7 0.074 18.37 0.38 20.83 0.04 71 EX-1.8 0.054 14.59 0.37 15.69 0.12 53 EX-1.9 0.061 12.84 0.25 < 25 EX-1.10 0.037 11.76 0.17 13.34 0.34 < 25 EX-1.11 0.204 24.32 0.25 98 EX-1.12 0.135 24.13 0.34 75 EX-1.13 0.096 23.59 0.30 65 EX-1.14 0.091 21.64 0.20 51 EX-1.15 0.072 18.27 0.28 44 EX-1.16 0.069 16.75 0.23 45 EX-1.17 0.189 24.14 0.19 42.30 2.66 153 EX-1.18 0.124 24.71 0.18 30.34 0.87 106 EX-1.19 0.102 23.92 0.28 24.75 0.24 68 EX-1.20 0.074 21.63 0.31 58 EX-1.21 0.071 18.83 0.24 18.47 0.19 50 EX-1.22 0.306 23.05 0.19 19.59 0.27 EX-1.23 0.187 22.90 0.14 19.71 0.55 EX-1.24 0.130 21.98 0.21 19.03 0.44 EX-1.25 0.124 21.82 0.23 EX-1.26 0.088 20.61 0.17 19.53 0.46 EX-1.27 0.389 9.31 0.09 EX-1.28 0.208 13.58 0.20

[0142] Example Set 2: RNS on THV film with Configuration B

[0143] Example Set 2 (EX SET 2) comprises random nanostructures on a substrate that is a THV film, varying the HMDSO flow rate and line speed, with HMDSO delivered through the alternative manifold configuration (Configuration B). Detailed process conditions can be found in Table 10, noting that for all samples the O2gas flow rate was 750 sccm and the power was 9000 W.

[0144] The 232 peel force and 5498 peel force for EX SET 2 are shown in Table 11. The peel force response was linear with HMDSO exposure for the lowest flow of HMDSO (29 sccm) investigated, but for the range of other flows (33-53 sccm) there was an optimum HMDSO exposure. This is again a result of approaching the continuous film limit at high HMDSO exposure values (e.g., slower line speeds or higher HMDSO flows) where a critical thickness is reached such that no substantial etching to form nanostructure occurs.

[0145] With Configuration B, there is not only an increase in the rate of adhesion increase with HMDSO exposure, but it is also possible to achieve higher adhesion to the surface working within other system constraints as discussed previously (limited down-web length, mass flow controller limitations, etc.).

[0146] Selected samples were examined with scanning electron microscopy (SEM) to determine the average nanostructure height. The average nanostructure height is shown in Table 11. The nanostructure height versus HMDSO exposure for CE SET 2 (white circles) and EX SET 2 (shaded circles) comparing Configuration A and B for THV is shown in FIG.10. Following from the adhesion results, it was possible to achieve taller nanostructures with Configuration B working within other system constraints as discussed previously (limited down-web length, mass flow controller limitations, etc.).

[0147] For samples where the nanostructure height was measured, the 5498 peel force versus nanostructure height for EX SET 2 was determined proportional to the feature height, as expected. Table 10. ID HMDSO Line Speed Residence HMDSO Pressure Flow (fpm) Time (sec) INT Flux (mtorr) (sccm) (sccm*sec) EX-2.1 29 10 30 870 9.2 EX-2.2 29 15 20 580 9.5 EX-2.3 29 20 15 435 9.9 EX-2.4 29 24 12.5 363 10.2 EX-2.5 29 30 10 290 10.6 EX-2.6 33 10 30 990 9.6 EX-2.7 33 15 20 660 9.9 EX-2.8 33 20 15 495 10.3 EX-2.9 33 24 12.5 413 10.6 EX-2.10 33 30 10 330 13.3EX-2.11 37 10 30 1110 8 EX-2.12 37 15 20 740 8.2 EX-2.13 37 20 15 555 8.5 EX-2.14 37 24 12.5 463 8.7 EX-2.15 37 30 10 370 9 EX-2.16 45 10 30 1350 8.7 EX-2.17 45 15 20 900 8.9 EX-2.18 45 20 15 675 9.1 EX-2.19 45 24 12.5 563 9.3 EX-2.20 45 30 10 450 9.5 EX-2.21 53 10 30 1590 9.5 EX-2.22 53 15 20 1060 9.7 EX-2.23 53 20 15 795 9.8 EX-2.24 53 24 12.5 663 10 EX-2.25 53 10 30 870 9.2 Table 11. ID Si k-alpha 232 Tape 232 Tape 5498 Tape 5498 Tape Ave Peel Ave Peel Stdev Peel Ave Peel Stdev Nanostructure (N / in) (N / in) height (nm) EX-2.1 0.273 22.60 0.49 42.30 1.21 189 EX-2.2 0.240 23.69 0.37 40.72 1.72 197 EX-2.3 0.226 23.49 0.35 33.42 0.68 123 EX-2.4 0.202 21.86 0.42 24.81 0.88 83 EX-2.5 0.193 17.78 0.28 14.93 0.79 40 EX-2.6 0.348 20.48 1.09 10.77 0.63 EX-2.7 0.316 22.57 0.45 30.99 0.37 EX-2.8 0.290 21.78 0.55 28.10 0.74 EX-2.9 0.250 21.49 0.28 30.88 0.35 EX-2.10 0.257 20.62 0.22 21.85 0.34 EX-2.11 0.415 16.73 1.14 12.38 0.36 EX-2.12 0.291 21.30 0.84 11.27 0.22 EX-2.13 0.250 23.18 0.49 18.04 0.52 EX-2.14 0.263 22.84 0.47 24.53 0.20 EX-2.15 0.240 19.82 0.18 17.51 0.62 EX-2.16 0.664 8.42 0.11 EX-2.17 0.51572 9.04 0.10EX-2.18 0.38081 10.98 0.38 EX-2.19 0.33567 12.52 0.70 EX-2.20 0.31104 15.77 1.01 EX-2.21 0.78366 7.91 0.20 EX-2.22 0.57924 8.02 0.07 EX-2.23 0.50251 8.60 0.16 EX-2.24 0.46789 8.86 0.17 EX-2.25 0.36617 9.94 0.13

[0148] Example Set 3: Nanostructures on polyurethane film with Configuration B

[0149] Example Set 3 (EX SET 3) comprises random nanostructure on a substrate that is a polyurethane film varying the HMDSO flow rate and line speed, with HMDSO delivered through the alternative manifold configuration (Configuration B). Detailed process conditions can be found in Table 12, noting that for all samples the HMDSO gas flow rate was 10 sccm, the O2gas flow rate was 750 sccm, the power was 9000 W, and the pressure was 8.9 milliTorr (mtorr).

[0150] The 232 peel force for EX SET 3 is shown in Table 12. Even with the limited range of conditions investigated, with Configuration B there was again an increase in the rate of adhesion increase with HMDSO exposure, and it was also possible to achieve higher adhesion to the surface working within other system constraints as discussed previously (limited down-web length, mass flow controller limitations, etc.). This demonstrates the utility of the alternative process gas configuration for working with relatively low etch rate materials, such as polyurethane. Table 12. ID Line Residence HMDSO Si k- 232 Tape 232 5498 Speed Time (sec) INT Flux alpha Peel Ave Tape Tape (fpm) (sccm*sec) (N / in) Peel Peel Stdev Ave (N / in) EX-3.1 5 60 600 25.00 N / A 45 EX-3.2 10 30 300 21.62 0.16 EX-3.3 5 60 600 0.021 8.29 0.14

[0151] Example Set 4: Nanostructures on PET film with Configuration B

[0152] Example Set 4 (EX SET 4) comprises random nanostructures on a substrate that is a PET film, varying the HMDSO flow rate and line speed, with HMDSO delivered through the alternative manifold configuration (Configuration B). Detailed process conditions can be found in Table 13, noting that for all samples the O2gas flow rate was 750 sccm.

[0153] The 232 peel force for EX SET 4 is shown in Table 14. With Configuration B, there may be a small increase in the rate of adhesion increase with HMDSO exposure but the difference is less significant, owing to the relatively high etch rate of PET. For materials where the etch rate is relatively high, maximizing the down-web distance after mask deposition becomes less important. Table 13. ID HMDSO Power (W) Line Speed Residence HMDSO Pressure Flow (fpm) Time (sec) INT Flux (mtorr) (sccm) (sccm*sec) EX-4.1 10 9000 7.5 40 400 8.1 EX-4.2 10 9000 10.0 30 300 8.2 EX-4.3 10 9000 10.0 30 300 8.1 EX-4.4 10 9000 10.0 30 300 9.5 EX-4.5 10 9000 20.0 15 150 8.4 EX-4.6 10 9000 20.0 15 150 9.7 EX-4.7 12 9000 20.0 15 180 9.2 EX-4.8 12 9000 24.0 12.5 150 9.4 EX-4.9 12 9000 30.0 10 120 9.6 EX-4.10 12 11000 20.0 15 180 10.2 EX-4.11 12 11000 24.0 12.5 150 10.4 EX-4.12 14 11000 20.0 15 210 10.2 EX-4.13 14 9000 15.0 20 280 9.7 EX-4.14 14 11000 24.0 12.5 175 10.6 EX-4.15 14 11000 30.0 10 140 10.8 EX-4.16 15 9000 7.5 40 600 8.1 EX-4.17 15 9000 10.0 30 450 8.3 EX-4.18 15 9000 10.0 30 450 10.2 EX-4.19 15 9000 10.0 30 450 9.6 EX-4.20 15 9000 10.0 30 450 7.8 EX-4.21 15 9000 10.0 30 450 8.6 EX-4.22 15 9000 15.0 20 300 10.5 EX-4.23 15 9000 15.0 20 300 9.9 EX-4.24 15 9000 15.0 20 300 8.1 EX-4.25 15 9000 15.0 20 300 9.0 EX-4.26 15 9000 20.0 15 225 8.5 EX-4.27 15 9000 20.0 15 225 10.8 EX-4.28 15 9000 20.0 15 225 10.1EX-4.29 15 9000 20.0 15 225 8.2 EX-4.30 15 9000 20.0 15 225 8.4 EX-4.31 15 9000 24.0 12.5 188 10.6 EX-4.32 15 9000 24.0 12.5 188 8.4 EX-4.33 15 9000 24.0 12.5 188 8.8 EX-4.34 15 11000 15.0 20 300 9.8 EX-4.35 15 11000 20.0 15 225 10.1 EX-4.36 20 9000 7.5 40 800 8.0 EX-4.37 20 9000 10.0 30 600 8.4 EX-4.38 20 9000 10.0 30 600 10.2 EX-4.39 20 9000 10.0 30 600 8.2 EX-4.40 20 9000 15.0 20 400 10.6 EX-4.41 20 9000 15.0 20 400 8.3 EX-4.42 20 9000 20.0 15 300 10.9 EX-4.43 20 9000 20.0 15 300 8.6 EX-4.44 20 9000 24.0 12.5 250 10.7 EX-4.45 20 9000 24.0 12.5 250 8.6 EX-4.46 20 9000 30.0 10 200 10.8 EX-4.47 20 9000 30.0 10 200 8.7 EX-4.48 20 11000 20.0 15 300 11.8 EX-4.49 20 11000 20.0 15 300 9.2 EX-4.50 20 11000 30.0 10 200 11.7 EX-4.51 20 11000 30.0 10 200 9.4 Table 14. ID 232 Tape 232 Tape Peel Ave Peel Stdev (N / in) EX-4.1 24.05 0.46 EX-4.2 24.03 0.70 EX-4.3 23.74 0.23 EX-4.4 22.03 0.37 EX-4.5 15.95 0.22 EX-4.6 15.89 0.28 EX-4.7 18.30 0.15 EX-4.8 20.22 0.38 EX-4.9 15.07 0.21EX-4.10 18.31 0.72 EX-4.11 15.06 0.29 EX-4.12 21.86 0.42 EX-4.13 26.77 0.37 EX-4.14 21.23 0.38 EX-4.15 16.68 1.68 EX-4.16 24.22 0.43 EX-4.17 24.66 0.52 EX-4.18 25.22 0.37 EX-4.19 24.43 0.38 EX-4.20 25.36 0.24 EX-4.21 25.44 0.33 EX-4.22 25.39 0.27 EX-4.23 25.54 0.41 EX-4.24 25.82 0.31 EX-4.25 26.05 0.22 EX-4.26 23.64 0.35 EX-4.27 24.44 0.32 EX-4.28 25.74 0.36 EX-4.29 23.95 0.29 EX-4.30 23.79 0.37 EX-4.31 20.57 0.22 EX-4.32 21.25 0.20 EX-4.33 21.27 0.20 EX-4.34 26.09 0.36 EX-4.35 24.29 0.43 EX-4.36 24.54 0.20 EX-4.37 25.32 0.65 EX-4.38 24.52 0.49 EX-4.39 24.48 0.38 EX-4.40 25.08 0.14 EX-4.41 25.35 0.24 EX-4.42 24.25 0.35 EX-4.43 25.19 0.82 EX-4.44 21.96 0.41 EX-4.45 23.89 0.32 EX-4.46 18.92 0.23EX-4.47 21.16 0.11 EX-4.48 25.60 0.55 EX-4.49 25.25 0.34 EX-4.50 19.72 0.36 EX-4.51 17.75 0.23

[0154] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

[0155] Furthermore, all publications and patents referenced herein are incorporated by reference in their entirety to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description prevails. Various exemplary embodiments have been described. These and other embodiments are within the scope of the following claims.

Claims

What is claimed is:

1. A continuous method for making a nanostructured surface, the method comprising: placing a substrate on a cylindrical electrode in a vacuum vessel; introducing at a first location in the vacuum vessel a first gaseous species capable of depositing a layer onto the substrate when formed into a plasma; introducing at a second location in the vacuum vessel a second gaseous species capable of etching the substrate when formed into a plasma, wherein the first location is closer to an entrance of the vacuum vessel at an unwind side than to the second location; generating a plasma from the first gaseous species and the second gaseous species between the cylindrical electrode and a counter-electrode; rotating the cylindrical electrode to translate the substrate; and exposing a major surface of the substrate to the plasma, wherein a layer is deposited on at least a portion of the major surface of the substrate and the substrate is etched, thereby forming nanostructures comprising at least one of nano-pillars, nano-columns, or continuous nano-walls comprising nano-pillars or nano-columns.

2. The method of claim 1, wherein the first location is within a sector from 0-90° as measured from the entrance of the vacuum vessel into a reaction zone around the cylindrical electrode.

3. The method of claim 1, wherein the second gaseous species is introduced at the second location through a tube comprising an array of holes or slots, wherein the array is substantially parallel to an axis of rotation of the cylindrical electrode.

4. The method of claim 3, wherein a length of the array is equal to or greater than a width of the substrate.

5. The method of claim 3, wherein the array is located greater than 3 centimeters (cm) and less than 30 cm away from a surface of the cylindrical electrode.

6. The method of any of claims 1 to 5, wherein the first gaseous species is introduced at a flow rate of less than one half, less than one fourth, less than one eighth, or less than one tenth, of the flow rate of the second gaseous species, in units of standard cubic centimeters per minute (sccm).

7. The method of any of claims 1 to 6, wherein the first gaseous species is mixed with a noble gas or an etchant gas.

8. The method of any of claims 1 to 7, wherein the substrate comprises a (co)polymeric material.

9. The method of claim 8, wherein the (co)polymeric material comprises a (co)polymer selected from the group consisting of a poly(methyl methacrylate), a poly(ethylene terephthalate), apolycarbonate, a cellulose, a triacetate, a polyamide, a polyimide, a fluoropolymer, a polyolefin, a siloxane (co)polymer, a cyclic olefin (co)polymer, a polyurethane, and combinations thereof.

10. The method of any of claims 1 to 9, wherein the substrate comprises a transparent (co)polymeric material.

11. The method of any of claims 1 to 10, wherein the first gaseous species comprises a compound selected from the group consisting of organosilicon compounds, metal alkyl compounds, metal isopropoxide compounds, metal oxide compounds, metal acetylacetonate compounds, metal halide compounds, and combinations thereof.

12. The method of claim 11, wherein the organosilicon compounds comprise tetramethylsilane, trimethylsilane, hexamethyldisiloxane, tetraethylorthosilicate, a polyhedral oligomeric silsesquioxane, or a combination thereof.

13. The method of any of claims 1 to 10, wherein the second gaseous species comprises oxygen, a fluorocarbon, nitrogen trifluoride, sulfur hexafluoride, chlorine, hydrochloric acid, methane, or a combination thereof.

14. An article made according to the method of any of claims 1 to 13, having nano-pillars or nano- columns.

15. The article of claim 14, wherein an average height of the nano-pillars or nano-columns is greater than 50 nanometers (nm), greater than 75 nm, or greater than 100 nm.

16. The article of claim 14 or claim 15, wherein the nano-pillars or nano-columns are substantially co-planar.

17. The article of any of claims 14 to 16, provided in a form of a roll.

18. The article of any of claims 14 to 17, wherein the nanostructures are overlaid with a pressure sensitive adhesive or a thermoset material.

19. The article of claim 18, wherein a force required to peel the pressure sensitive adhesive away from the nanostructured substrate is greater than 15 N / in, measured according to the 232 Tape Peel Test.

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