Optically active nano-achiral composite materials and methods for making the same

Abstract

An optically active nanocomposite material is provided that may have a textured substrate and a multilayer optic stack with a plurality of layers comprising nanoplatelets. The nanoplatelets may be achiral and formed of a material such as transition metal chalcogenides, Mxenes, or nanocarbons. The optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD) and optional circular dichroism (CD). The nanocomposite may have an optical asymmetry g-factor of greater than or equal to about 1. Further, the nanocomposite is thermally stable, for example, to a temperature of greater than or equal to about 250° C. Different methods of fabricating such nanocomposites using layer-by-layer (LBL) processes are also provided.

Description

Attorney Docket No.2115-008388-WO-POA OPTICALLY ACTIVE NANO-ACHIRAL COMPOSITE MATERIALS AND METHODS FOR MAKING THE SAME CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 603,846, filed on November 29, 2023. The disclosure of the above application is incorporated herein by reference in its entirety. GOVERNMENT SUPPORT

[0002] This invention was made with government support under 2243104 awarded by the National Science Foundation and N00014-18-1-2876 awarded by the U.S. Office of Naval Research. The government has certain rights in the invention. FIELD

[0003] The present disclosure relates to robust, optically active additively engineered composites formed from two-dimensional achiral nanoplatelet materials with strong circular polarization and methods for making the same. BACKGROUND

[0004] This section provides background information related to the present disclosure which is not necessarily prior art.

[0005] Photonics devices have a wide range of uses, including for robotic perception systems, holographic technologies, information encryption protocols, through-space communications, and power plant monitoring, among others. Many of these applications require variable and intense polarization rotation, as well as tolerance to extreme environments where they are exposed to extreme conditions like high or low temperatures, high or low pressures, radiation and the like (e.g., nuclear reactors, ocean floor, deserts). However, many current photonic devices are based on liquid crystals (LC) with small molecules or organic polymers that cannot be used at extreme temperatures. For example, working temperatures cannot exceed 100 °C for most devices based on liquid crystal (LC) technology due to temperature-sensitive phase transitions, recrystallization processes, and oxidation reactions. Other technologies may involve nanocomposite films made from zero- and one-dimensional building blocks, that is, nanoparticles and nanofibers, which display resilience to oxidation paired with high circular dichroism (CD) and optical asymmetry g-factors that are essential figures of merit for chiral optics. However,Attorney Docket No.2115-008388-WO-POA current chiral nanocomposites remain vulnerable to temperature-induced dehydration and phase transitions.

[0006] Nacre-like layered composites from two-dimensional (2D) nanomaterials are known for their toughness, fire-resistance, and optical transparency. These properties are assets for ruggedized polarization optics, but their use in chiral photonic components seems counterintuitive. Weak CD could be obtained due to molecular scale chiral features, but making nanoplatelets with strong nanoscale chirality, optical polarization rotation and high g-factor is fundamentally problematic due to their rigidity and high energy required for their twisting and strong un-polarized scattering. Additionally, the layered structure of 2D nanomaterials is much more difficult to reconfigure without structural damage as compared to LCs. Thus, it would be advantageous to develop optically active nanocomposite materials that are robust and stable in a wide variety of environments, while exhibiting strong chirality, optical polarization, and a high optical asymmetry g-factor, among other properties. SUMMARY

[0007] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0008] In certain aspects, the present disclosure relates to an optically active nanocomposite material. The optically active nanocomposite material comprises a textured substrate and a multilayer optic stack disposed on the textured substrate. The multilayer optic stack comprises at least one layer comprising a plurality of nanoplatelets. The optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD), has an optical asymmetry g-factor of greater than or equal to about 1, and is stable to a temperature of greater than or equal to about 250°C.

[0009] In one aspect, the multilayer optic stack comprises a plurality of layers in addition to the at least one layer comprising the plurality of nanoplatelets. The multilayer optic stack defines a first axis for linear birefringence (LB) and a second axis that defines linear dichroism (LD). An angular offset is defined between the first axis and the second axis.

[0010] In one further aspect, the multilayer optic stack further comprises a layer comprising a plurality of anisotropic nanoparticles.

[0011] In one further aspect, the plurality of anisotropic nanoparticles is selected from the group consisting of: nanowires, nanorods, nanotubes, and combinations thereof.

[0012] In one further aspect, the plurality of anisotropic nanoparticles comprises nanowires comprising silver.Attorney Docket No.2115-008388-WO-POA

[0013] In one further aspect, the multilayer optic stack further comprises a layer comprising an achiral dye.

[0014] In one further aspect, the textured substrate is in a deformed state when the plurality of layers are deposited thereon. The textured substrate can transition from the deformed state to a relaxed state to define a plurality of wrinkles or cracks in the multilayer optic stack.

[0015] In one aspect, the optically active nanocomposite material further displays circular dichroism (CD).

[0016] In one aspect, the optically active nanocomposite material is stable to the temperature of greater than or equal to about 300°C.

[0017] In one aspect, the plurality of nanoplatelets comprises a material selected from the group consisting of: transition metal chalcogenides, two-dimensional MXene carbides or nitrides represented by a general formula Mn+1XnTx, where M represents a transition metal, X represents carbon or nitrogen, n can be from 1 to 4, and Tx represents terminations on an outmost transition metal layer surface, nanocarbons, and combinations thereof.

[0018] In one aspect, the plurality of nanoplatelets comprises a material selected from the group consisting of: molybdenum disulfide (MoS2), tungsten disulfide (WS2), rhenium disulfide (ReS2), molybdenum ditelluride (MoTe₂), tungsten ditelluride (WTe₂), niobium disulfide (NbS₂), niobium diselenide (NbSe₂), tantalum disulfide (TaS₂), tantalum diselenide (TaSe₂), and rhenium diselenide (ReSe₂), titanium carbide (Ti3C2Tx) where x ranges from 0 to 2, vanadium carbide (V₂C), niobium carbides (Nb₂C, Nb₄C₃), molybdenum carbide (Mo₂C), titanium carbonitride (Ti₃CN), chromium carbide (Cr₂C); titanium nitride (Ti₄N₃), and vanadium carbide (V₄C₃), graphene, graphene oxide (GO), reduced graphene oxide (rGO), and carbon nitride (C₃N₄), and combinations thereof.

[0019] In one aspect, the multilayer optic stack comprises at least one bilayer that comprises the plurality of nanoplatelets in a first layer and further comprises poly(diallyldimethylammonium chloride) (PDDA) in a second layer.

[0020] In one aspect, the textured substrate has a diagonal pattern relative to a major dimension defined therein.

[0021] In one further aspect, the diagonal pattern comprises a plurality of grooves.

[0022] In one aspect, the plurality of nanoplatelets has an average maximum dimension of greater than or equal to about 100 nm to less than or equal to about 500 nm.

[0023] In another aspect, the present disclosure also provides a resonator cavity comprising the optically active nanocomposite material as described above.Attorney Docket No.2115-008388-WO-POA

[0024] In certain other aspects, the present disclosure relates to an optically active nanocomposite material that comprises a multiple layer optic stack comprising a plurality of nanoplatelets. The optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD) and has an optical asymmetry g-factor is greater than or equal to about 1 and is stable to a temperature of greater than or equal to about 250 °C.

[0025] In yet other aspects, the present disclosure relates to a method for forming an optically active nanocomposite material. The method may comprise applying a first charged material having a first polarity to a substrate having a second polarity opposite to the first polarity. The method may further comprise applying a second charged material having the second polarity over the first charged material in a layer-by-layer process. The first charged material and the second charged material are distinct from one another and selected from a polymer and a plurality of nanoplatelets. The method further comprises repeating the applying of the first charged material and the applying of the second charged material to form the optically active nanocomposite material comprising multiple layers comprising the polymer and the plurality of nanoplatelets. The method forms the optically active nanocomposite material that displays both linear birefringence (LB) and linear dichroism (LD) and has an optical asymmetry g-factor is greater than or equal to about 1.

[0026] In one aspect, the substrate is under an applied force and in a first twisted state during the applying of the first charged material, during the applying of the second charged material, and during the repeating. The method further comprises permitting the substrate to relax from the first twisted state to a second relaxed state to facilitate at least one of wrinkling, crackling, or buckling of the optically active nanocomposite material comprising multiple layers.

[0027] In one aspect, the substrate is a textured substrate that comprises a plurality of grooves.

[0028] In one further aspect, the plurality of grooves are formed by imprinting the substrate or a layer disposed on the substrate with a stamp via soft lithography.

[0029] In one aspect, the textured substrate has a diagonal pattern relative to a major dimension defined therein and the diagonal pattern comprises a plurality of grooves.

[0030] In one aspect, the first charged material is the polymer that is positively-charged and the second charged material is the plurality of nanoplatelets that is negatively-charged.

[0031] In one aspect, the first charged material comprises poly(diallyldimethylammonium chloride) (PDDA) and the second charged material comprises the plurality of nanoplatelets.

[0032] In one aspect, the plurality of nanoplatelets comprises a material selected from the group consisting of: transition metal chalcogenides, two-dimensional MXene carbides or nitridesAttorney Docket No.2115-008388-WO-POA represented by a general formula Mn+1XnTx, where M represents a transition metal, X represents carbon or nitrogen, n can be from 1 to 4, and Tx represents terminations on an outmost transition metal layer surface, nanocarbons, and combinations thereof.

[0033] In one aspect, the plurality of nanoplatelets comprises a material selected from the group consisting of: molybdenum disulfide (MoS2), tungsten disulfide (WS2), rhenium disulfide (ReS2), molybdenum ditelluride (MoTe₂), tungsten ditelluride (WTe₂), niobium disulfide (NbS₂), niobium diselenide (NbSe₂), tantalum disulfide (TaS₂), tantalum diselenide (TaSe₂), and rhenium diselenide (ReSe₂), titanium carbide (Ti3C2Tx) where x ranges from 0 to 2, vanadium carbide (V₂C), niobium carbides (Nb₂C, Nb₄C₃), molybdenum carbide (Mo₂C), titanium carbonitride (Ti₃CN), chromium carbide (Cr₂C); titanium nitride (Ti₄N₃), and vanadium carbide (V₄C₃), graphene, graphene oxide (GO), reduced graphene oxide (rGO), and carbon nitride (C₃N₄), and combinations thereof.

[0034] In one aspect, the method further comprises applying a layer comprising a third charged species comprising a plurality of anisotropic nanoparticles.

[0035] In one aspect, the anisotropic nanoparticles are selected from the group consisting of: nanowires, nanorods, nanotubes, and combinations thereof.

[0036] In one aspect, the method further comprises aligning the plurality of anisotropic nanoparticles on the substrate by one or more alignment processes selected from the group consisting of: high-speed spraying under shear force, alignment by an external electric field, alignment by an external magnetic field, Langmuir-Blodgett alignment technique, and combinations thereof.

[0037] In one aspect, the method further comprises applying a layer comprising a third charged species comprising an achiral dye.

[0038] In one aspect, the optically active nanocomposite material further displays circular dichroism (CD).

[0039] In certain further aspects, the present disclosure relates to a method for forming an optically active nanocomposite material. The method may comprise applying a plurality of nanoplatelets to a surface of a polymeric substrate to define a texture comprising a plurality of grooves. The applying includes one or more processes selected from the group consisting of: microcontact printing by pressing a stamp having the plurality of nanoplatelets disposed thereon onto the surface, ink jet printing the plurality of nanoplatelets onto one or more target regions of the surface, screen printing, spin coating, or both screen printing and spin coating the plurality of nanoplatelets onto the surface, applying the plurality of nanoplatelets to one or more exposed regions on the surface having a photolithography treated layer disposed thereon, and combinationsAttorney Docket No.2115-008388-WO-POA thereof. The method thus forms the optically active nanocomposite material having an optic layer comprising the plurality of nanoplatelets disposed over the polymeric substrate. The optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD) and has an optical asymmetry g-factor is greater than or equal to about 1.

[0040] In certain other aspects, the present disclosure relates to a method for controlling chirality of an optically active nanocomposite material. The method comprises directing at least one of: (i) an external electric field, (ii) an external magnetic field, or (i) and (ii) towards the optically active nanocomposite material to modify a circular dichroism (CD) exhibited by the optically active nanocomposite material. The optically active nanocomposite material comprises a textured substrate and a multilayer optic stack disposed on the textured substrate, wherein the multilayer optic stack comprises at least one layer comprising a plurality of nanoplatelets. The optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD), has an optical asymmetry g-factor of greater than or equal to about 1, and is stable to a temperature of greater than or equal to about 250°C.

[0041] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS

[0042] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0043] FIGS. 1A–1G. Optically active nanocomposite materials made from two- dimensional (2D) nanomaterials prepared by a first method according to certain aspects of the present disclosure, with uniform, tunable left- and right-handed polarization rotation. FIG. 1A shows a schematic of the first method according to certain aspects of the present disclosure (referred to herein as Method 1 or “M1”). FIG.1B shows a photograph of left-handed (LH) and right-handed (RH) composites made from achiral Ti3C2Txnanoplatelets deposited on grooved polyethylene terephthalate (PET). FIG.1C shows a three-dimensional and FIG.1D shows high- magnification atomic force microscope images showing that layer-by-layer (LBL) deposition of Ti3C2Txnanoplatelets in the PDMS grooves results in nanoscale wrinkles. FIG.1E shows circular dichroism (CD) spectra and FIG. 1F shows CD mapping of the composites at each maximum polarization rotation amplitude for LH (left) and RH (right) M1-composites of Ti3C2Tx using MMP. FIG. 1G shows dependence of CD intensities on the dihedral angle between linearAttorney Docket No.2115-008388-WO-POA birefringence (LB) and linear dichroism (LD), and α, of the composites prepared according to certain aspects of the present disclosure.

[0044] FIGS. 2A–2I. Optically active nanocomposite materials made from two- dimensional (2D) nanomaterials prepared by a second method according to certain aspects of the present disclosure show real-time reconfigurable polarization rotation. FIG.2A shows a schematic of the second method according to certain aspects of the present disclosure (referred to herein as Method 2 or “M2”). FIG.2B shows a photograph of Ti3C2Txnanoplatelet composites assembled by an LBL method on a twisted polydimethylsiloxane (PDMS) strip and the corresponding released state. FIG.2C shows three-dimensional atomic force microscope images for the wrinkled (left) and cracked (right) sides of RH M2-composites of Ti3C2Tx. FIG.2D shows CD spectra for the composites under a 10% tensile strain. FIG. 2E shows CD mapping at each maximum polarization rotation amplitude for the LH (left) and RH (right) composites under various strain amplitudes. FIG.2F shows cycling tests for the polarization rotation of M2-composites of Ti3C2Tx under a periodic 10% tensile strain. FIG.2G shows scanning electron microscopy image of silver (Ag) nanowire films with a controlled orientation. FIG. 2H shows CD spectra for 25%-strained composites with Ag nanowire films under various α via rotating Ag nanowire films and FIG.2I shows corresponding dependence of g-factor with α.

[0045] FIGS. 3A–3G show optically active nanocomposite materials made from two- dimensional (2D) nanomaterials prepared by certain aspects of the present disclosure generating and modulating strong circularly polarized light emission (CPLE). FIG.3A shows schematics for the generation of CPLE with M2-composites that contain a linear dichroism (LD) layer of nanoplatelet wrinkles and a linear birefringence (LB) layer of strained PDMS. FIG. 3B shows CPLE spectra for rhodamine 6G under the modulation of an unstrained M2-composite of Ti3C2Tx with a 25%-strained PDMS, at various α via rotating the LD direction in the x-y plane. FIGS.3C– 3E show dependence of gem on α for the composites with LD from FIG.3C: the unstrained Ti3C2Tx composite, FIG. 3D: an aligned silver (Ag) nanowire film, and FIG. 3E: a linear polarizer. FIG. 3F shows a normalized CPLE spectra (left) and corresponding emission photographs (right) for different fluorescent dyes modulated with Ti3C2Tx nanoplatelet composites at α of 30 (dash) and 330o(solid). FIG.3G shows photographs to image the circular polarization of emission with LH and RH circular filters for the fluorescent dyes of cascade blue acetyl azide (blue) and rhodamine 6G (green) with polarization modulated with composites that had different LD originations.

[0046] FIGS. 4A–4D show polarization imaging in the near-infrared range using thermally resilient composites formed in accordance with certain aspects of the present disclosure. FIG.4A shows schematics of circularly polarized optical imaging with LH and RH composites.Attorney Docket No.2115-008388-WO-POA FIG.4B shows images and corresponding intensity profiles for the LH and RH polarized flame recorded by a NIR camera incorporated with M2-composites of Ti3C2Tx nanoplatelets and silver (Ag) nanowire layers for circular polarization filtering. FIG. 4C shows dependence of temperatures on circular dichroism (CD) for different composite films. FIG. 4D shows dependence of the polarization anisotropy for flame with LH NIR polarization.

[0047] FIGS.5A–5B show schematics of mechanisms of light-matter interactions leading to circular polarization of the transmitted beam. In FIG.5A, differential transmittance for LH and RH circularly polarized light passing through composites with LB and LD strata formed according to a first fabrication method of the present disclosure is shown. FIG. 5B shows a comparative differential transmittance and attenuation of the LH and RH circularly polarized light with conventional chiral structures of different types.

[0048] FIG.6 shows an effect of geometric parameters of a pattern of a substrate, which impacts LD responses. More specifically, FIG. 6 illustrates a wrinkled pattern of a Ti3C2Txnanoplatelet layer, where a height, interval and thickness of 400 nm, 1000 nm, and 12 nm of wrinkles is shown disposed on the PDMS substrate.

[0049] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0050] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific compositions, components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0051] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, elements, compositions, steps, integers, operations, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Although theAttorney Docket No.2115-008388-WO-POA open-ended term “comprising,” is to be understood as a non-restrictive term used to describe and claim various embodiments set forth herein, in certain aspects, the term may alternatively be understood to instead be a more limiting and restrictive term, such as “consisting of” or “consisting essentially of.” Thus, for any given embodiment reciting compositions, materials, components, elements, features, integers, operations, and / or process steps, the present disclosure also specifically includes embodiments consisting of, or consisting essentially of, such recited compositions, materials, components, elements, features, integers, operations, and / or process steps. In the case of “consisting of,” the alternative embodiment excludes any additional compositions, materials, components, elements, features, integers, operations, and / or process steps, while in the case of “consisting essentially of,” any additional compositions, materials, components, elements, features, integers, operations, and / or process steps that materially affect the basic and novel characteristics are excluded from such an embodiment, but any compositions, materials, components, elements, features, integers, operations, and / or process steps that do not materially affect the basic and novel characteristics can be included in the embodiment.

[0052] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed, unless otherwise indicated.

[0053] When a component, element, or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other component, element, or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0054] Although the terms first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers and / or sections, these steps, elements, components, regions, layers and / or sections should not be limited by these terms, unless otherwise indicated. These terms may be only used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer or section discussedAttorney Docket No.2115-008388-WO-POA below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.

[0055] Spatially or temporally relative terms, such as “before,” “after,” “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially or temporally relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.

[0056] Throughout this disclosure, the numerical values represent approximate measures or limits to ranges to encompass minor deviations from the given values and embodiments having about the value mentioned as well as those having exactly the value mentioned. Other than in the working examples provided at the end of the detailed description, all numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. For example, “about” may comprise a variation of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in certain aspects, optionally less than or equal to 0.1%.

[0057] In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range, including endpoints and sub-ranges given for the ranges.

[0058] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0059] In various aspects, the present disclosure contemplates composites comprising two-dimensional (2D) nanomaterials that display uniquely high electrical, thermal, and mechanical properties. Pairing robustness of such composites with polarization rotation is needed for hyperspectral optics in extreme conditions. However, rigid nanoplatelets have randomized achiral shapes, which scramble the circular polarization of photons with comparable wavelengths. In accordance with various aspects of the present disclosure, an optically active nanocomposite material comprises an optic stack, which may have multiple layers, and which comprises aAttorney Docket No.2115-008388-WO-POA plurality of nanoplatelets or 2D nanomaterials, which can be paired with a textured surface. In this manner, the nanoplatelets strongly and controllably rotate light polarization based on positioning in the layers and on the textured surface, despite being nano-achiral. Here, chiral and achiral features reflect that certain molecules, nanoparticles, or nanostructures have non-superimposable (chiral) or superimposable (achiral) mirror images, which manifest as different extinction coefficients to left-handed and right-handed circularly polarized light (LCP and RCP). Chiroptical activity can be measured by circular dichroism (CD) spectrometry, where circular dichroism (CD) is differential absorption to LCP and RCP and expressed as: CD = Extinction of LCP – Extinction of RCP, where extinction is the sum of absorption and scattering. By “optically active” it is meant that the material exhibits circular birefringence, an ability to rotate the polarization plane of light, such as manifested in chiral molecules and nanostructures. It can be scaled by CD based on Kramers–Kronig transformation and highly correlated with other optical polarization properties such as linear birefringence (LB, the refraction difference to linearly polarized light with orthogonal polarization directions) and linear dichroism (LD, the extinction difference to linearly polarized light with orthogonal polarization directions). In preferred aspects, the optically active composite exhibits at least LB and LD and preferably also exhibits CD and optical rotation.

[0060] The intense circular dichroism in nanocomposite films prepared in accordance with certain aspects of the present disclosure can originate from a textured or patterned surface below an optic layer or stack, for example, a multi-layered optic stack that comprises a plurality of layers, where the textured surface has a diagonal pattern of wrinkles, grooves or ridges, which can lead to an angular offset between axes of linear birefringence (LB) and linear dichroism (LD) for the stack. Stratification of the layer-by-layer (LBL) nanocomposites prepared in accordance with certain aspects of the present disclosure thus enables precise engineering of the polarization-active materials from imprecise nanoplatelets with an optical asymmetry g-factor that can be greater than or equal to about 1.0, in certain variations, exceeding those of typical nanomaterials by approximately 500 times.

[0061] Moreover, the nanoplatelets may be made from inorganic or other thermally stable materials, so that the composites formed in accordance with certain aspects of the present disclosure exhibit high thermal resilience. For example, an optically active nanocomposite material formed in accordance with the present disclosure may be heat resistant and thus stable to a temperature of greater than or equal to about 250 °C, optionally greater than or equal to about 275 °C, and in certain variations, optionally greater than or equal to about 300 °C. By “stable” it is meant that the composite material maintains desired properties, like circular birefringence and circular dichroism, at elevated temperatures, while also remaining physically stable so that it doesAttorney Docket No.2115-008388-WO-POA not suffer undue physical damage, such as substantial phase changes like melting or permanent mechanical deformation. By way of example, an optically active composite prepared in accordance with certain aspects of the present disclosure can enable operating temperatures as high as 250 °C or more and imaging of hot emitters in the near-infrared part of the spectrum. Such multilayered optic stacks can be formed by layer-by-layer techniques to form nanocomposites with achiral dyes, which results in anisotropic factors for circularly polarized emission approaching the theoretical limit. The generality of the observed phenomena is demonstrated by nanocomposite polarizers in the form of nanoplatelets.

[0062] In certain aspects, the composites formed in accordance with the present disclosure may have nanoparticles with platelet-like shapes also considered to be a two-dimensional (2D) particle. While retaining the planar shape, the particle may also be elongated, e.g., the particle may also display aspect ratios for major planar axes other than unity. A platelet-like shape is typically flattened, for example, a plate that may have an oval (e.g., disc), polygonal (e.g., trapezoidal or rectangular), or irregular shape. As used herein, platelets and flakes are used interchangeably. In certain variations, the platelet-shaped nanoparticle or nanoplatelet may have an average particle size diameter of greater than or equal to about 50 nm to less than or equal to about 1,000 nm. In certain aspects, the plurality of nanoplatelets used in a composite (to form a nanocomposite) may have a maximum average dimension of greater than or equal to about 100 nm to less than or equal to about 500 nm with a monolayer dominated nanoplatelet structure. The nanoplatelets may have a maximum average particle size that is less than a dimension of a feature of a pattern in which they are deposited, for example, having a maximum average particle size less than a width of a groove of a pattern, so that the nanoplatelet can be disposed therein. Further, a multilayer structure may have greater than or equal to about 2 to less than or equal to about 10 layers. In this aspect, the aspect ratio (AR) may be as defined as AR = L / H, where L is the length of the longest axis (here the major lateral axis) and H is height. A platelet generally defines a nanoscale particle with AR of greater than or equal to about 3 to less than or equal to about 100.

[0063] In certain aspects, the plurality of nanoplatelets comprises a material selected from the group consisting of: transition metal chalcogenides, MXene materials, nanocarbons, and any combinations thereof. MXene materials are two-dimensional thin layers of carbides, nitrides, or carbonitrides typically represented by the general formula Mn+1XnTx, where M represents a transition metal, X represents carbon or nitrogen, n can be from 1 to 4, and Txrepresents terminations on an outmost transition metal layer surface. MXene nanoplatelets may include titanium carbide (Ti₃C₂T^), where T represents terminations on an outmost transition metal layer surface, such as functional groups, like oxygen (–O), hydroxyl (–OH), or fluoride (–F) on a surfaceAttorney Docket No.2115-008388-WO-POA of the MXene material. x ranges from 0 to about 2. Other suitable MXene materials may include vanadium carbide (V₂C), niobium carbides (Nb₂C, Nb₄C₃), molybdenum carbide (Mo₂C), titanium carbonitride (Ti₃CN), chromium carbide (Cr₂C); titanium nitride (Ti₄N₃), and / or vanadium carbide (V₄C₃). In one variation, the MXene may comprise titanium carbide (Ti3C2Tx) where x is from 0 to 2, by way of non-limiting example.

[0064] In certain variations, the transition metal chalcogenide, such as a transition metal dichalcogenide nanoplatelet. The transition metal chalcogenide may comprise molybdenum disulfide (MoS2), tungsten disulfide (WS2), rhenium disulfide (ReS2), molybdenum ditelluride (MoTe₂), tungsten ditelluride (WTe₂), niobium disulfide (NbS₂), niobium diselenide (NbSe₂), tantalum disulfide (TaS₂), tantalum diselenide (TaSe₂), and rhenium diselenide (ReSe₂), by way of non-limiting example. As a further example, the nanoplatelets may comprise carbon-based materials, such as nanocarbon, including graphene, graphene oxide (GO), reduced graphene oxide (rGO), and carbon nitride (C₃N₄).

[0065] These various materials tend to be thermally stable and resistant to chemical and corrosive attack. Further, while these materials / particles are not optically active or chiral themselves and have randomized achiral shapes that can scramble circular polarization of photons with comparable wavelengths, when incorporated into a nanocomposite layer in an optic layer, such as a multilayer optic stack, and especially when disposed on a textured surface, they can exhibit desired optical activity. For example, these nanoplatelets may have different orientations and position controlments. As will be described further herein, such nanoplatelet materials can be used with various different manufacturing methods according to certain aspects of the present disclosure for forming an optically active nanocomposite material. In this manner, in accordance with the present teachings, a large family of optical nanocomponents can be computationally designed and additively engineered for ruggedized optics.

[0066] In certain alternative variations, these nanocomposites may be composed of alternative nanoparticles, such as nanowires, nanorods, and nanotubes. As will be described below, in certain variations, a multilayer optic stack comprises a plurality of layers, where at least one layer may comprise a plurality of nanoplatelets, while another layer may comprise a plurality of nanowires, nanorods, or nanotubes. In this manner, nanocomposites are composed of diverse components, such as nanoplatelets, nanowires, nanorods, and nanotubes, which contribute to the tunability and modulation of their circular dichroism responses across different frequency bands.

[0067] Robust, thermally-stable, optically active nanocomposite materials can be formed via layer-by-layer (LBL) deposition of 2D nanoscale components into optical media layers, such as stacked optical media layers, with tunable linear dichroism (LD) and linear birefringence (LB)Attorney Docket No.2115-008388-WO-POA that can be additively engineered for specific wavelengths. For example, these nanocomposite materials can be used in resonant cavities for lasing at visible (e.g., wavelengths of light ranging from greater than or equal to about 380 nm to less than or equal to about 740 nm), infrared (IR) having wavelengths ranging from greater than or about 750 nm to less than or equal to about 1 mm, including near infrared (NIR)(e.g., wavelengths ranging from about 750 nm (0.75 micrometers) to about 1.4 micrometers), short wave infrared (SWIR), mid wave infrared (MWIR), long wave infrared (LWIR), and far infrared (FIR),), far-IR (e.g., wavelengths of light ranging from greater than or equal to about 15 micrometers to less than or equal to about 1 mm), and THz ranges (e.g., wavelengths of light ranging from greater than or equal to about 30 micrometers to less than or equal to about 3 mm), by way of example. The optically active nanocomposites exhibit tunable circular dichroism (CD) across a broad range of wavelengths, including visible, near- infrared (NIR), infrared (IR), far-infrared (FIR), and terahertz (THz) frequencies. These nanocomposites may comprise various components, such as nanoplatelets, nanowires, nanorods, and nanotubes, which contribute to the tunability and modulation of their circular dichroism responses across different frequency bands.

[0068] Moreover, the circular dichroism response of these nanocomposite materials can be enhanced by integrating nanocomposites within resonant cavities, trapping photons between two reflective surfaces. For example, an optical or resonant cavity may have at least a first reflective surface and a second reflective surface parallel to each other and spaced apart from one another to define a resonator cavity. The nanocomposite may be disposed within the resonator cavity. This allows certain wavelengths to constructively interfere and enhance specific resonance modes that align with the CD response of the nanocomposite. High refractive index materials, such as gold and silver can effectively confine light, creating stronger near-field interactions that intensify chiral light-matter interactions. In various aspects, the present technology contemplates varying the cavity thickness (ranging from nano- to micro-scale dimensions, for example, a microscale is typically at least one dimension of less than about 1,000 micrometers and a nanoscale is at least one dimension of less than about 1 micrometer (i.e., 1,000 nm)) and the materials used in the nanocomposites, the resonance can be tuned across visible, NIR, IR, FIR, and THz ranges, enabling chiral lasing devices with high efficiency and tunable output characteristics.

[0069] All the components and composites are achiral at the scales relevant to experimentally observed polarization rotation, which makes the optical response conceptually different from deformation-induced, lithographically-defined, and assembly-facilitated out-of- plane chirality investigated in the past. The generality of the observed phenomena wasAttorney Docket No.2115-008388-WO-POA demonstrated by composite polarizers made from three chemically diverse 2D nanomaterials, such as titanium carbide (Ti3C2Tx) representing MXenes, molybdenum sulfide (MoS2) representing transition metal chalcogenides, and graphene oxide (GO) representing nanocarbons. Using Ti3C2Txas an example of a suitable inorganic achiral nanoplatelet particle, at least two distinct manufacturing methods are described herein to generate nanoscale surface textures with centimeter-scale dimensions showcasing their scalability.

[0070] Multiscale chirality of nanoplatelets can be explained as follows. The chiroptical activity of chemical structures is dependent on the amplitude of electromagnetic resonances and their left / right asymmetry. When the frequency match for resonance is satisfied, chiroptical activity will be the highest when the wavelength of photons is comparable to the size of chiral objects. Nanostructured materials display chirality at multiple scales and their chiroptical activity is maximized when they display high left / right asymmetry at the scale comparable to the wavelength of the photon. As such, chiral plasmonic particles and assemblies have strong chiroptical activity for visible wavelengths because their dimensions of about 100 nm are complemented by high mirror asymmetry. The latter can be quantified as Hausdorff chirality measure (HCM) or Osipov–Pickup–Dunmur chirality index (OPD) exceeding 0.2 and 5.0, respectively.

[0071] Nanoplatelets of 2D materials used in accordance with certain aspects of the present disclosure, exemplified by Ti3C2Tx, MoS2 or GO, show only weak, if any, chiroptical activities. Their mirror asymmetry at atomic scale can be high (Harsdorf Chirality Measure (HCM) of approximately 0.3, Osipov-Pickup-Dunmur (OPD) of approximately 0.001) due to, for instance, amino acid surface ligands, but the characteristic size of the asymmetric tetrahedrons around the α-carbon is small at approximately 0.3 nm. Thus, photons with 200 nm to 300 nm wavelengths matching in energy with resonant electronic transitions, produce only weak CD peaks with an amplitude of 1–10 mdeg, which are smaller than those for many nanoscale (bio)molecules. Chirality measures for the same nanoplatelets at 100 nm scale are near zero (HCM = 7.9 × 10-2, OPD = -6.4 × 10-5) due to the rigidity of the 2D material and irregular shapes, which makes them nano-achiral. Consequently, the chiroptical activity for MoS2 and Ti3C2Tx nanoplatelets with various amino acid ligands around the electronic oscillation band and band gaps is weak or near zero.

[0072] However, nanoplatelet composites prepared in accordance with certain aspects of the present disclosure exhibit chiroptical activity. The nanocomposite may include a multilayer optic stack comprising a plurality of layers at least some of which comprise the nanoplatelets described above. Thus, the multilayer optic stack defines a first axis for linear birefringence andAttorney Docket No.2115-008388-WO-POA a second axis that defines linear dichroism. An angular offset may be defined between the first axis and the second axis. In certain aspects, a substrate or first layer may exhibit the linear birefringence (LB) and a second layer may exhibit linear dichroism (LD), where an angular offset is defined between the first axis and the second axis. Notably, in certain variations, the substrate may exhibit linear birefringence (LB), while the one or more layers of the stack may exhibit linear dichroism (LD). The presence of LB- and LD-active strata along the light path results in polarization rotation and strong CD, which is typically treated as an artifact complicating measurements of “true” isotropic CD related to chirality. The LB component of the optical media splits the light beam propagating along the z-axis into “slow” and “fast” wave packets with orthogonal polarizations. Subsequent passage through LD-active media serving as an imperfect linear polarizer retains their phase lag, resulting in strong ellipticity for the combined transmitted beam.

[0073] 2D nanomaterials or nanoplatelets can display LD and LB, but the typical layered nanocomposites made from them are x-y isotropic because nanoplatelets are placed randomly on the surface. However, when the multilayer optic stack is formed by the methods contemplated herein that may involve layer-by-layer (LBL) deposition or other techniques, LB / LD activity is imparted to the material and, thus, CD by adding surface textures along the z-axis.

[0074] In certain variations, the methods of making the optically active nanocomposite material may involve layer-by-layer (LBL) deposition. The LBL technique relies on alternating adsorption of charged species or polyelectrolytes onto a substrate. Layers may be built up by sequential dipping of a substrate into oppositely charged solutions having oppositely charged moieties that are attracted to the surface. Additional steps may occur between application steps, such as washing of the surface before application of the next material. Monolayers of individual components attracted to each other by electrostatic and van-der-Waals interactions are thus sequentially adsorbed on the substrate. Multiple deposition cycles of first and second charged materials can be repeated sequentially to build alternating layers in a multilayered structure. A layered material formed by LBL is often referred to as: (polyanion / polycation)n, where n represents the number of deposition cycles or layers present. Each polyanion / polycation layer may be considered to be a bilayer. LBL films or coatings can be constructed on a variety of solid substrates, thus imparting much flexibility for size, geometry and shape and further patterned or etched (with chemicals, plasma, electron beam, or high intensity lasers, for example).

[0075] Thus, the methods of the present disclosure may involve a layer-by-layer (LBL) process that optionally comprises disposing materials on a substrate having a first polarity. In certain variations, the substrate may first be treated to impart a first polarity. The methodAttorney Docket No.2115-008388-WO-POA optionally comprises applying a first charged material having a second polarity to at least one surface on the substrate having the first polarity opposite to the second polarity. The method also includes applying a second charged material having the first polarity over the first charged material in the LBL process on the at least one surface of the substrate. The first charged material and the second charged material are distinct from one another and define at least one layer of a multilayered coating or stack formed herein (having alternating layers of the first charged material and the second charged material). As will be appreciated, this process can be repeated to form a multilayered stack comprising a plurality of layers.

[0076] In certain aspects, the substrate may have a negative charge or may be treated to impart a negative charge. In one example, the substrate may comprise a polymer, such as polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), or the like. In certain aspects, the substrate may include a charged material or moiety and may be cleaned, for example, with a Piranha solution followed by a plasma treatment (e.g., oxygen plasma treatment). In certain aspects, after treatment, the polymeric substrate has a negative charge. In other aspects, the substrate may be coated with polymeric material or treated with other chemicals, electron beam, or high intensity lasers, for example.

[0077] As will be described further below, in certain variations, the surface of the substrate defines a textured substrate, which may define a pattern of features. For example, FIG.6 illustrates a textured substrate (polydimethyl siloxane (PDMS)) having a wrinkled or undulating pattern on which a nanoplatelet layer may be disposed, where a height, interval and thickness may be, by way of non-limiting example, 400 nm, 1000 nm, and 12 nm respectively. In certain variations, the textured substrate may have a pattern that is disposed diagonally to a major dimension (e.g., to length and / or width) defined therein. See for example, FIG. 1A. In certain variations, a pattern may comprise a plurality of grooves interspersed with a plurality of lands. The grooves may have a diagonal pattern with respect to a major dimension of the substrate, for example, disposed at an angle with respect to x and y directions (e.g., in FIG.1A, shown at an angle (α, 45°) with respect to either x or y directions). In other variations, the textured substrate may be one that is reversibly deformable, for example, flexible, so that it may be twisted, flexed, or otherwise physically deformed when force is applied in a first state, while the substrate returns to a second relaxed state when the force is removed. Thus, in certain aspects, the textured substrate may be in a deformed state when the multiple layer optic stack layers are deposited thereon, for example, in a twisted state, which can transition from the deformed state to a relaxed state to facilitate at least one of wrinkling, crackling, or buckling of the optically active nanocomposite material comprising multiple layers and in this manner defines a plurality of wrinkles or cracks in the multiple layerAttorney Docket No.2115-008388-WO-POA optic stack having been deposited thereon. Therefore, a texture can be imposed onto the multiple layer stack of composite material.

[0078] In one aspect, the first charged material may be applied over the negatively charged substrate. In certain aspects, the first charged material may be a polycation. In certain aspects, the first charged material may be poly(dimethyldiallylammonium chloride) (PDDA), polyurethane (PU), or combinations thereof. In one aspect, the first charged material is poly(dimethyldiallylammonium chloride) (PDDA).

[0079] Next, a second charged material may be formed over the first charged material. In certain aspects, the second charged material may be a polyanion. In certain aspects, the second charged material may be a plurality of anionic or negatively charged platelet-shaped nanoparticles. In certain variations, a bilayer may be formed that comprises the PDDA and negatively charged nanoplatelets. The methods of depositing the first and second charged materials may be repeated to form a multilayered optic stack comprising a plurality of layers including nanoplatelets that provide optical activity. In this manner, an optically active nanocomposite material comprises the multilayer optic stack comprising a plurality of layers deposited via LBL.

[0080] In certain aspects, the mutlilayered optic stack comprises at least two layers of the plurality of positive layers that each comprises a cationic poly(diallyldimethylammonium chloride) (PDDA) and at least two layers of the plurality of negative layers that each comprises the anionic nanoplatelet particles.

[0081] According to various aspects of the present disclosure, the methods may also include further treating or reacting surfaces of the plurality of platelet-shaped nanoparticles to include chiral ligands. For example, such chiral ligands may include penicillin or an amino acid, such as lysine, cysteine, arginine, or alanine, and achiral ligands, such as polyoxometalates, mercaptopropionic acid mercaptoundecanoic acid, and the like. In certain aspects, a variety of chiral surface ligands were not found to impart strong chirality to the nanoplatelets, for example, modification of MoS2 with cysteine and Ti3C2Tx with lysine resulted in stable colloidal dispersions for processing. For example, in the case of Ti3C2Tx, this was particularly important because of the well-known difficulties with its delamination. Strong van der Waals attraction of the Ti3C2Tx nanoplatelets was overcome by bonding with amino acids, resulting in steric repulsion and adding positive charge resulting in electrostatic repulsion.

[0082] Furthermore, in other aspects of the present disclosure, a layer comprising a plurality of anisotropic nanoparticles may be incorporated into the stack, for example, as a top or outermost layer deposited during the LBL process. The inclusion of one or more layers comprising an anisotropic nanoparticle can optimize polarization contrast, for example, controlling theAttorney Docket No.2115-008388-WO-POA circular polarization modulation capabilities in a nearly linear way. In one aspect, the plurality of nanowires, nanorods, and nanotubes comprises a material selected from plasmonic nanostructures. In certain variations, the anisotropic nanoparticles are selected from the group consisting of: nanowires, nanorods, nanotubes, and combinations thereof. For example, the nanowires or nanorods may be formed of an electrically conductive metal, such as silver (Ag), such as silver nanowires, gold (Au), such as gold nanorods, copper (Cu), aluminum (Al), or may be nanotubes such as carbon nanotubes.

[0083] The present disclosure contemplates making the optically active nanocomposites by a variety of methods including the following. First, the present disclosure contemplates a variety of methods for patterning nanoplatelets on a polymer substrate. For example, soft lithography templates can be used to form predetermined patterns on a surface of a substrate that then has the nanoplatelets deposited thereon. In one variation, the deposition of the nanoplatelets may include layer-by-layer (LBL) deposition described above. Thus, in one variation, nanoplatelets are LBL deposited into pre-formed grooves on a polymeric substrate. These grooves are initially formed or transferred to the substrate using a polydimethylsiloxane (PDMS) stamp via a soft lithography process. This technique defines the LBL deposition of nanoplatelets to form a well-defined and patterned structure, enabling high-resolution spatial arrangement of nanoplatelet layers with scalability beyond centimeter dimensions.

[0084] In another method, the nanoplatelets may be deposited via layer-by-layer (LBL) deposition onto a twisted substrate followed by mechanical relaxation. Thus, nanoplatelets may be LBL deposited onto a flexible substrate (e.g., a PDMS strip or sheet) that has been mechanically deformed or twisted, resulting in regions of compression on one side and stretching on the other. Upon carefully relaxing the twisted (e.g., PDMS) substrate, the nanoplatelet-coated strip or sheet recovers its original shape, which is transferred onto the polymer substrate, creating unique cracked and wrinkled patterns due to differential mechanical relaxation between compression and stretching.

[0085] In certain aspects, the present disclosure contemplates methods for forming an optically active nanocomposite material that comprise applying a plurality of nanoplatelets to a surface of a polymeric substrate to define a texture comprising a plurality of grooves. The applying includes one or more processes for applying the nanoplates to the surface. Such processes may be selected from the group consisting of: microcontact printing by pressing a stamp having the plurality of nanoplatelets disposed thereon onto the surface, ink jet printing the plurality of nanoplatelets onto one or more target regions of the surface, screen printing, spin coating, or both screen printing and spin coating the plurality of nanoplatelets onto the surface, applying theAttorney Docket No.2115-008388-WO-POA plurality of nanoplatelets to one or more exposed regions on the surface having a photolithography treated layer disposed thereon, and combinations thereof to form the optically active nanocomposite material having an optic layer comprising the plurality of nanoplatelets disposed over the polymeric substrate. The optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD) and has an optical asymmetry g-factor is greater than or equal to about 1 and may include any of the features or variations previously described above.

[0086] For example, in one method, nanoplatelets may be transferred onto the polymer substrate via a microcontact printing process. Nanoplatelets may be transferred onto the polymer substrate by pressing a PDMS stamp coated with nanoplatelets onto the substrate surface. This method allows the creation of fine, reproducible nanoplatelet patterns, which are capable of producing high-resolution designs.

[0087] In a further method, nanoplatelet-containing droplets may be ink jet printed. Droplets containing dispersed nanoplatelets are deposited via inkjet printing onto targeted regions of the polymer substrate, for example, according to programmable and predetermined designs. This method enables precise placement and pattern customization, with adjustable parameters for droplet volume, nanoplatelet concentration, and deposition layout.

[0088] In yet another method, the nanoplatelets may be deposited via screen printing and spin coating with a patterned groove mask. Nanoplatelets may be deposited onto the polymer substrate using either screen printing or spin coating in combination with a patterned mask featuring groove-shaped hollow regions. The mask restricts the deposition, ensuring that nanoplatelets are applied only to specific areas of the substrate, resulting in precise, well-defined patterns.

[0089] The present disclosure also contemplates photolithography-assisted deposition of nanoplatelets. Nanoplatelets are patterned using a photosensitive polymer layer. After ultraviolet exposure and development to form the pattern, the surface has a photolithography treated layer. The nanoplatelets are then deposited onto the exposed areas of the substrate having the photolithography treated layer, enabling high-resolution patterning.

[0090] As described above, in certain variations, the optically active nanocomposite may include a multilayer stack that in addition to one or more layers comprising nanoplatelets, further includes one or more layers comprising an anisotropic nanoparticle, such as a nanowire, nanorod, or nanotube, of a plasmonic material. Such anisotropic materials may be aligned in the layer in which they are present.Attorney Docket No.2115-008388-WO-POA

[0091] The present disclosure contemplates different methods for aligning nanowires, nanorods, and / or nanotubes on a textured substrate. In one variation, such a method may comprise high-speed spraying under shear force for alignment of the anisotropic nanoparticles. Nanowires, nanorods, and nanotubes are sprayed at high speeds, for example, spraying at a flow rate of greater than or equal toa bout 20 liters / min, across the textured substrate, generating a shear force that aligns the nanostructures along the direction of motion.

[0092] In another method, the anisotropic particles may be aligned under electric and magnetic fields. For example, nanostructures may be aligned across the textured substrate by applying an external direct current (DC) electric field, for example, having a strength of greater than or equal to about 10⁴ V / m, or a magnetic field with a strength greater than or equal to about 1.6 Tesla to align the nanoparticles.

[0093] In yet another variation, a Langmuir–Blodgett technique can be used for alignment of the anisotropic nanoparticles. Nanowires, nanorods, and nanotubes are deposited as a monolayer at an air-water interface, and then transferred to the textured substrate. The alignment is thus achieved by controlling surface tension and compression forces during transfer.

[0094] By way of example, in a first method of the present disclosure (referred to herein as Method 1 or M1) shown in FIGS.1A–1G, a polydimethylsiloxane (PDMS) layer is coated onto polyethylene terephthalate (PET) substrates with strong linear birefringence (LB) followed by imprinting submicron scale grooves. For example, soft lithography with a patterned or wrinkled stamp may be used. In one variation, the imprinted submicron grooves may have a typical interval of 740 ± 60 nm and depth of 120 ± 20 nm, respectively. Nanoplatelets of 2D nanomaterial are conformally deposited on the PDMS grooves by the LBL deposition of negatively-charged nanoplatelets and positively-charged PDDA with a total thickness determined by the numbers of bilayers. As such, in one variation, ten (10) bilayers of Ti3C2Tx-PDDA produce a coating with a thickness of 27 ± 3 nm. Importantly, the platelets of 2D materials (here Ti3C2Tx) coating the walls of the grooves are stacked, which results in a composite with high refractive index and an electrical dipole orthogonal to the z-axis. When the dihedral angles between the grooves and inherent or “built-in” LB axis of PET are +45° (left-handed, LH, composites) and -45° angles (right-handed, RH, composites), strong monopolar CD with opposite signs are observed (FIGS. 1E–1F). The shape of the spectrum matches the theoretical ones based on LB / LD interactions nearly perfectly.

[0095] In a second method according to certain other aspects of the present disclosure (referred to herein as Method 2 or M2) shown in FIGS. 2A–2I, LBL films are deposited, for example, by a layer-by-layer (LBL) deposition process of alternating layers of PDDA and nanoplatelets, onto twisted PDMS sheets (where they are deformed under applied force) followedAttorney Docket No.2115-008388-WO-POA by their relaxation to the flat state (FIGS.2A–2B). The compressed side produces cracked films with a typical thickness of 130 ± 20 nm, while the stretched side produces wrinkled films with a height of 680 ± 82 nm (FIG. 2C). LB in these materials emerges from the PDMS substrate and increases when the substrate is stretched (FIG.2D). The LD activity originates from the wrinkled and cracked patterns of the LBL films, again, resulting in electrical polarization vectors oscillating orthogonally to the z-axis. Testing different conditions of stretching and twisting, produces wrinkles at +45° (LH composites) and -45° angles (RH composites) with respect to the long axis of the substrates.

[0096] As described above, a wide range of 2D nanoplatelet materials can be used for both the first and second fabrication methods according to certain variations of the present disclosure, as demonstrated by the use of Ti3C2Tx, MoS2and GO nanoplatelets, by way of non-limiting example. In all cases, centimeter-scale samples with uniform optical properties were obtained. In all cases, the 2D materials produce composite solids with stiffness, hardness, and substrate adhesion far exceeding the conventional chiroptical materials. The rigidity of nanoplatelets, however, does not allow them to twist and they remain nano-achiral or nano-racemic in both types of multilayered composites formed via the first or second fabrication methods described just above.

[0097] Structural tuning of polarization rotation is also contemplated. Attaining high isotropic or “true” CD can require simultaneous optimization of the chirality measures, sizes, and resonance energies of chiral chemical objects, which are subject to a long list of chemical and physical constraints. The stratified optical media with LB and LD components de-couples these parameters and simplifies the materials design process. Following Mueller calculus for light- matter interactions, CD of a transmitted light beam ideally obeys the dependence: CD ∝ LB ∙ LD^ = LB ∙ LD ∙ cos(2 α − 90^) (Eq. 1)where LB characterizes the linear birefringence of PET (as in the first method (M1) described above) or PDMS (as in the second method (M2) described above) along the y-axis (FIG. 1A), while LD represents linear dichroism at 45oin agreement with the convention of Mueller calculus; the latter can be altered by the dihedral angle, α, between LD and LB. This dependence is tested for several experimental parameters. For example, α can be varied by changing the direction of grooves (as in the first method (M1)) (FIG. 1G) or the direction of cracks / wrinkles (as in the second method (M2)). A nearly perfect agreement with Equation 1 is observed for all cases of composites of different handedness, shape, peak position, polarity and α. CD maxima were observed at α = 45oand 135owith preferred LH and RH circular polarization effect for the transmitted photons.Attorney Docket No.2115-008388-WO-POA

[0098] CD amplitude rises approximately proportionally to the number of LBL deposition cycles for both composites formed via either the first fabrication method (M1) or second fabrication method (M2) instead of expected quadratic dependence, which is indicative of the compensatory effects related potentially to additional light-matter interactions.

[0099] Strain applied to the material can strongly change LB, LD, and α. Stretching the composites made via the second fabrication method (M2) up to 31% increases LB, and thus CD (Eq. 1). After removing the strain, the spectra returned to their original states, which can be repeated at least 1,000 times without polarization loss (FIG. 2F). Mueller matrix polarimetry (MMP) mapping reveals that the chiroptical response remained homogenous even under tensile strains as high as 50% (FIG.2E). In addition, with increasing strain amplitudes, the direction of cracks / wrinkles gradually aligned towards the strain direction, resulting in the decrease of α and LD’ as well as the saturation and slow decrease of CD beyond 15% strain.

[0100] Tuning the optical activities in different strata is facilitated by the additive nature of LBL films. Additional LD activity can be imparted by depositing a layer of aligned rod-like plasmonic materials, for example, anisotropic nanoparticles like silver (Ag) nanowires by a grazing incidence spray-LBL (FIG.2G). A single layer of Ag nanowires enhanced LD amplitude approximately 5 to 10 times compared to the nanoplatelet wrinkles, enabling high g-factors without difficulties in chemical synthesis. The magnitude of polarization rotation reached as much as 3,500 millidegrees with a maximum g-factor of greater than about 1.0 (FIGS.2H and 2I), which exceeds the highest g-factors of 0.1–0.4 reported for nanoparticles in dispersion and comparable to or exceeding g-factors of 0.5–2 reported for Bouligand structures.

[0101] Circularly polarized photoluminescence of optical nanomaterials. Additive engineering of LB / LD active composites can also be applied to the circular polarization of photoluminescence. 2D nanomaterials display strong luminescence, but “true” circularly polarized light emission (CPLE) with a high emission asymmetry factor, gem, is more difficult to obtain than “true” CD. In the case of chiral molecules, a dilemma exists in that increasing optical asymmetry typically results in decreased luminescence quantum yield (Φlum), owing to the non- radiative dissipation of excited state energy.

[0102] Programmable LD and LB of nanocomposites can be harnessed to achieve a high gemwith a Φlumapproaching unity, even for achiral fluorescent dyes as shown in FIG. 3A. For example, rhodamine 6G (Φlum= 0.95) is an achiral fluorescent molecule without any CPLE; however, when it was incorporated with composites of Ti3C2Tx nanoplatelets formed via second method (M2), strong CPLE is observed.Attorney Docket No.2115-008388-WO-POA

[0103] Elaborating on Equation 1 for emissive media, the structure-property relations for CPLE can be encapsulated in the relationship set forth in Equation 2: CPLE = CD ∙ ^ ∝ LB ∙ LD^ ∙ ^ = L ^^^^ ^^^ B ∙ LD ∙ cos(2 ^ − 90 ) ∙ ^^^^ (Eq. 2)

[0104] Experimental data validates this equation. Similar to CD, LH and RH emission can be attained from opposite α via changing the direction of cracks / wrinkles (FIGS.3B–3C), so that a gemas high as 0.11 can be obtained. The value is several orders of magnitude higher than the typical asymmetry factors for chiral fluorescence emitters with gem = glum = gCPL that are generally less than 0.01 and comparable to the asymmetry factors of 0.1–0.5 reported for lanthanide complexes and liquid crystal composites.

[0105] The strain of PDMS from 0–25% changes LB while LD is maintained as constant. A linear correlation between CPLE and gem responses with LB has been observed, in agreement with Equation 2. Stretching composites formed via the second method (M2) also demonstrates the real-time modulation of CPLE’s degree of ellipticity.

[0106] When nanocomposites including aligned Ag nanowire films were used to enhance LD, the same α-dependence is observed (FIG.3D). The ellipticity of emitted light was as high as 3.6 deg while gemwas as high as 0.19. Further optimization of LD’ with a linear polarizer enabled bright CPLE intensity with an ellipticity of 17 deg and gem of 1.6 (FIG. 3E), approaching the theoretical limit of 2.0, corresponding to perfect separation of LH and RH photons. Having a unique combination of high gemand ^^^^made possible visualization of CPLE with different helicities using a standard camera (FIG.3G).

[0107] Optical stacks with tunable α, LB and LD were made from a wide variety of achiral dyes and a large family of composite materials with gradually variable strong CPLE in different parts of the spectrum that would be nearly impossible using molecular or quantum-confined chiral structures. Incorporation of tryptophan (Φlum= 0.12), cascade blue acetyl azide dye (Φlum= 0.54), and IR-783 dye (Φlum = 0.11) with composites made via the second fabrication method (M2) using Ti3C2Txnanoplatelets, both positive and negative circular polarizations emissions at 360, 450, and 780 nm were obtained (FIGS.3F–3G).

[0108] Thermally resilient circular polarization imaging is also contemplated. As described above, elevated temperatures typically destroy circular polarization effects in current LCs, composites, or solutions. Commercial circular polarizers lose their optical activity at temperatures as low as 50 °C (FIG.4C). Cholesteric liquid crystals lose their optical activity above 90 °C. In contrast, composites of Ti3C2Tx nanoplatelets made via the second fabrication technique (M2) with and without a layer of added silver (Ag) nanowires exhibit intense circular polarization from 20 to 250 °C (FIG.4C).Attorney Docket No.2115-008388-WO-POA

[0109] Benefiting from its thermal stability, LBL Ti3C2Txcomposites may serve as an effective circular modulator for polarized imaging of hot emitters, particularly in the NIR range (FIG.4A). This is demonstrated by imaging flames from burning organic fuels with strong NIR radiation in the range of 1300–1500 nm, as shown in FIG. 4A, followed by their circular polarization modulated by composites fabricated via the second method (M2) comprising Ti3C2Tx nanoplatelets (FIG. 4B). As shown in FIG.4B, images and corresponding intensity profiles for the LH and RH polarized flame recorded by a NIR camera incorporated with M2-composites of Ti3C2Tx nanoplatelets and silver (Ag) nanowire layers for circular polarization filtering are shown.

[0110] The polarization contrast can be optimized in a highly predictable manner by the sequence of LBL layers of silver (Ag) nanowires to control the circular polarization modulation capabilities in a nearly linear way (FIG.4D). This capability can be expanded to any part of the NIR spectrum including those currently inaccessible with LCs and needed for a variety of technologies.

[0111] The combination of chiroptical, mechanical, and thermal properties demonstrated for layered nanocomposites from 2D materials (e.g., nanoplatelets) with LB / LD effects prepared in accordance with certain aspects of the present teachings are unique and conceptually difficult to achieve for conventional organic materials and nanostructures with isotropic CD. The manufacturing simplicity, materials modularity, and computational predictability of the additively engineered composites lead to a large family of optically active materials with millions of potential permutations of nanoscale components, organizational patterns, and optical effects.

[0112] In certain variations, the optically active nanocomposite material comprises a multilayer optic stack comprising a plurality of layers. The plurality of layers may comprise nanoplatelets. Further, the optically active nanocomposite material may be used in an optical cavity, which may be used for lasing or generating coherent light, as described above.

[0113] Additionally, such optically active nanocomposite materials may be used for electrically and magnetically modulated chiroptical properties. In various aspects, the present disclosure provides a nanocomposite with tunable CD response across a broad spectrum, including visible, NIR, IR, FIR, and THz frequencies, where the CD properties are dynamically modifiable through the application of an external field, such as external electric and magnetic fields.

[0114] In certain variations, the present disclosure contemplates a method for controlling chirality of an optically active nanocomposite material. The method may comprise directing at least one of: (i) an external electric field, (ii) an external magnetic field, or both (i) and (ii) towards the optically active nanocomposite material to modify a circular dichroism (CD) exhibited by the optically active nanocomposite material. The optically active nanocomposite material comprisesAttorney Docket No.2115-008388-WO-POA a textured substrate and a multilayer optic stack disposed on the textured substrate, wherein the multilayer optic stack comprises at least one layer comprising a plurality of nanoplatelets. The optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD), has an optical asymmetry g-factor of greater than or equal to about 1, and is stable to a temperature of greater than or equal to about 250°C. Such an optically active nanocomposite material may include any of the features or variations described previously above.

[0115] For example, application of an electric field alters the optical asymmetry of the nanocomposite, for example, by intercalating metal ions, such as Li⁺, Na⁺, or Zn²⁺, into the nanoplatelets. This intercalation modifies electrical dipole interactions between the nanoplatelet stacking layers, which in turn modulates the chiroptical properties. The field-induced changes are reversible, allowing for the reconfiguration of optical properties upon removal of the electric field.

[0116] Similarly, applying a magnetic field influences the magnetic dipole moments in the nanocomposite during light-matter interactions, enhancing or shifting the circular dichroism response. The strength and orientation of the magnetic field determine the extent of this modulation. The combination of electric and magnetic field modulation provides a robust and versatile mechanism for the real-time control of CD responses, particularly in the megahertz to gigahertz frequency range. This enables dynamic tuning of circular polarization for both photon transmission and emission, with applications in high-speed switching, chiral light-matter interactions, and advanced photonic, optoelectronic, and quantum technologies.

[0117] Various embodiments of the inventive technology can be further understood by the specific examples contained herein. Specific Examples are provided for illustrative purposes of how to make and use the compositions, devices, and methods according to the present teachings and, unless explicitly stated otherwise, are not intended to be a representation that given embodiments of this invention have, or have not, been made or tested.

[0118] Examples

[0119] L / D-Lysine (L / D-Lys), L / D-Penicillamine (L / D-Pen), L / D-Cysteine (L / D-Cys), L / D-Alanine (L / D-Ala), L / D-Arginine (L / D-Arg), biaxially oriented polyethylene terephthalate (PET), sulfonated reduced graphene oxide, cholesteryl pelargonate, tryptophan, IR-783, Rhodamine 6G, poly(sodium-4-styrenesulfonate) (PSS), poly(diallyldimethylammonium chloride) (PDDA), cellulose fiber, hydrochloric acid (HCl), sodium hydroxide (NaOH), and sulfuric acid (H2SO4, 98%) were purchased from Sigma-Aldrich. Cascade blue acetyl azide was purchased from Fisher Scientific. Silver (Ag) nanowires were purchased from ACS Material with an average diameter of 60 nm and length of 20–30 micrometers. Sylgard™ 184 silicone elastomerAttorney Docket No.2115-008388-WO-POA kit was purchased from Dow Corning Co., USA. Ultrapure deionized (DI) water (18.2 MΩ) was used for all solution preparations.

[0120] Preparation of Lys-capped Ti3C2Tx occurs according to previous protocols described in Shuck, C. E. et al., “Scalable Synthesis of Ti3C2TxMXene,” Adv. Eng. Mater.22, 1– 8 (2020) and Lioi, D. B. et al., “Electron-Withdrawing Effect of Native Terminal Groups on the Lattice Structure of Ti3C2Tx MXenes Studied by Resonance Raman Scattering: Implications for Embedding MXenes in Electronic Composites,” ACS Appl. Nano Mater. 2, 6087–6091 (2019), the relevant portions of both of which are incorporated herein by reference. 12.5 mg of pristine Ti3C2Tx flak was mixed with 125 mg lysine (Lys) in 50 mL DI solution and purged with high- purity nitrogen for at least 1 hour to remove any dissolved oxygen. The mixed solution was placed under a tip sonicator (Cole-Parmer Ultrasonic Processor, pulse amplitude of 35%) and sonicated for 2 hours to delaminate pristine Ti3C2Tx into dominant monolayers. The obtained solution was directly used for CD, SEM characterizations and LBL assemblies. For the sample used for XPS testing, 3 times of centrifugation with a speed of 14000 rpm (Legend X1R, Thermo Scientific) for 20 min were needed to wash out unbound Lys ligands in the solution.

[0121] Cysteine (Cys)-capped and penicillin (Pen)-capped molybdenum disulfide (MoS2) particles are prepared as follows. The pristine MoS2nanoplatelets were exfoliated with a liquid processing route of redox exfoliation by polyoxometalate macroanions into monolayers or multilayers and dispersed in acetonitrile with a concentration of 1.0 mg / mL, according to the protocols described in Jawaid, A. et al., “Redox Exfoliation of Layered Transition Metal Dichalcogenides,” ACS Nano 11, 635–646 (2017) and Jawaid, A. M., et al., “Mechanism for Redox Exfoliation of Layered Transition Metal Dichalcogenides,” Chem. Mater.32, 6550–6565 (2020), the relevant portions of which are incorporated herein by reference.100 microliters of as- made MoS2nanoplatelets was mixed with 900 microliters of 10 mM L / D-Cys or L / D-Pen then sonicated for 2 hours and stirred overnight to allow the Cys and Pen ligands to sufficiently graft onto the nanoplatelets. The obtained product was directly used for CD and SEM characterizations.

[0122] Both composites formed via the first fabrication method (M1) and the second fabrication method (M2) are formed on designed substrates with the LBL assembly of nanoplatelets, which impart exceptional capabilities to the resulting films, including: (1) self- limited deposition enabling conformal coating on complex surfaces; (2) high-temperature resilience and mechanical robustness of the resulting composite films; (3) strong adhesion to the wide range of substrates; (4) predictability of the optical properties; and (5) suitability for all or nearly 2D nanomaterials and all optical substrates.Attorney Docket No.2115-008388-WO-POA

[0123] Example 1

[0124] Fabrication of composites made by the first fabrication method (M1) is described in this example. For M1-composites, their fabrication was via the LBL assembly of nanoplatelets on biaxially oriented PET with grooves patterned by wrinkled stamps in a soft-lithography technique.

[0125] The process includes three steps (I)–(III) described herein.

[0126] (I) Preparation of wrinkled stamps. The wrinkled stamps were prepared by oxygen plasma etching to strained PDMS strips. PDMS strips were cut into 20 × 35 mm from PDMS films that were previously made by 20 mg SylgardTM184 silicone elastomer and 2.0 mg cross-linker base in a 12 × 12 cm petri dish. The obtained PDMS strip had a thickness of 1 mm and was 40%- strained along the length, fixed by clamps under the strain, and etched by oxygen plasma (Evactron® Plasma De-Contaminator™, 20 W for 20 min). Then, 5 alternating PSS / PDDA bilayer units were LBL deposited on the strained PDMS to act as a spacer between the PDMS stamp and patterned grooves. Releasing the PDMS strip from the clamps obtained wrinkled stamps with a groove interval and height / depth of 840 ± 60 and 230 ± 60 nm (Table 2 below). Similarly, the wrinkled stamps were made with 10%- and 20%-strained PDMS that formed wrinkles with groove intervals of 1220 ± 60 and 1030 ± 60 nm and heights of 90 ± 20 and 220 ± 50 nm, respectively. Commercial digital versatile discs were also used as wrinkled stamps with a corresponding groove interval and height of 760 ± 60 and 150 ± 10 nm.

[0127] (II) Soft-lithography to pattern grooves on PET.

[0128] The PET film (150 micrometers in thickness) serving as a substrate was cut into 75 × 50 mm, fixed on a glass slide, and treated with plasma clearing (5 W for 5 min) before dropping 300 microliters mixture solution of silicone elastomer and cross-linker base (1:10). After the addition of spacer (150 micrometers) and spreading out of dropped solution, the wrinkled stamps prepared in step (I) were covered onto the top of the solution with an angle of 135oand 45oto the uniaxially stretched axis of PET film for the fabrication of LH and RH composites (FIG. 1A). The obtained PET film was placed in a desiccator to remove bubbles and then cured at 60 °C overnight. Afterward, the PDMS stamp was peeled off to obtain PET film with pattered PDMS grooves. The PDMS layer has a thickness of 150 micrometers (μm) determined by the spacer with the same groove intervals as the wrinkled stamps.

[0129] (III) LBL assembly on the patterned PET. The PET film with patterned grooves underwent a cleaning and activation process to impart hydrophilic properties under an ultraviolet ozone surface cleaner (5 W for 1 min). The activated strip was dipped into a 0.5 wt.% PDDA solution for 5 min, then transferred to DI water to wash out unbound polymers, and dried withAttorney Docket No.2115-008388-WO-POA compressed air. Next, the positively charged PDMS strip was immersed into negatively charged Lys-capped Ti3C2Tx nanoplatelets solution for 10 min to assemble one layer of Ti3C2Tx, then transferred to DI water to wash out unbound Ti3C2Tx nanoplatelets, and dried with compressed air. The obtained strip was dipped into a PDDA solution to begin the next cycle of LBL assembly until 10 bilayers of Ti3C2Tx-PDDA deposition in the grooves. The formed wrinkled patterns of nanoplatelet films were well-aligned with a tilt angle of 45oand 135owith respect to the long axis of PET. A similar LBL assembly procedure was used to fabricate MoS2and GO composites with 5 bilayers of nanoplatelet-PDDA deposition considering the dominant multilayer nanostructures.

[0130] Example 2

[0131] Fabrication of composites made by the second fabrication method (M2) is described in this example. For M2-composites, their fabrication was via the LBL assembly of nanoplatelets on a twisted substrate of PDMS strips, followed by a releasing process to flatten twisted assembles to obtain composites with cracked and wrinkled patterns on the compressed and stretched sides. This process was divided into two steps (I)–(II) described herein.

[0132] (I) Fabrication of twisted substrate. PDMS strips were cut into a size of 10 × 45 mm, twisted 360°in either a clockwise or anticlockwise direction to get the LH and RH PDMS substrate, and fixed on the glass slide with clamps for further usage.

[0133] (II) LBL assembly of nanoplatelets on the twisted PDMS. The twisted PDMS strip was cleaned and activated with hydrophilic properties under plasma cleaner (20 W for 20 minutes). Then the activated strip was covered by a layer of PDDA and rinsed by negatively charged Lys-capped Ti3C2Txnanoplatelets solution for 5 minutes to fully deposit one layer of Ti3C2Tx. Repeating the LBL cycles until a composite film with 6 bilayers of Ti3C2Tx-PDDA formed on each side of the twisted PDMS. Afterward, releasing the twisted strip from clamps obtained M2-composites of Ti3C2Txfor characterization. The same LBL assembly procedure was used to fabricate M2-composites of MoS2 via the electrostatic interaction of positively charged PDDA with negatively charged MoS2 nanoplatelets covered with polyoxometalates.

[0134] Example 3

[0135] Fabrication of Ag nanowire films incorporated into the multilayer composite stack is described. A glass slide was cleaned with ethanol under sonication and then plasma-cleaned to make the slide hydrophilic. A layer of PEI was deposited on the hydrophilic substrate by LBL assembly under the spraying of PEI and rinsed with water to wash out unbound PEI. Afterward, a suspension of Ag nanowires was sprayed on the PEI-coated substrate along airflow with a spraying nozzle (B1 / 4J, Spraying Systems) to align the Ag nanowires on the substrate via a grazing incidence spraying method. Under the airflow, the Ag nanowires suspension was atomizedAttorney Docket No.2115-008388-WO-POA into small droplets and aligned on the substrate under the shear force along the direction of airflow. The liquid flow rate was set to 1 mL / min using a liquid pump (M50, Valco Instruments Co.), while the airflow rate was set to 30 L / min with a flow meter (Red-Y, Vögtlin Instruments GmbH). The incidence angle of the shear force spray was 10°. The distance from the nozzle to the substrate was 1.0 cm. Deposition for 200 seconds provided a dense film with one layer of Ag nanowires. The obtained glass with well-aligned Ag nanowires was rinsed with water and dried with compressed air.

[0136] Simulations and Experimental Data

[0137] A commercial software package of Lumerical Finite-Difference Time-Domain (FDTD) Solutions was used for simulations to calculate the extinction, CD and LD spectra of Ti3C2Txand Ag nanowire composites, as well as corresponding electrical field distributions under the light-matter interaction process according to Maxwell’s equations.

[0138] To compare the CD response of M2-composites of Ti3C2Tx with experiments, the models of cracked and wrinkled Ti3C2Txpatterns were created with 3ds Max according to geometrical parameters from scanning electron microscopy (SEM) and atomic force microscope (AFM) images. The Ti3C2Tx models were illuminated by LH and RH circularly polarized light, which contained two total-field scattered-field sources with the same k- vector but with a phase difference of −90° / 90° for LH / RH circularly polarized light. Two analysis groups including a box of power monitors were used to calculate the absorption and scattering intensity. The extinction and CD spectra were recorded as the extinction’s average and difference under LH and RH circularly polarized light. To keep consistent with the experiments, the beam source was irradiated from the z-axis, while Ti3C2Tx models were rotated in the x-y plane with an angle difference of 10°from 0° to 170° to remove linear effects.

[0139] The LD response of Ti3C2Txand Ag nanowire composites was calculated under the illumination of two linearly polarized light with the same k-vector along the z-axis but differing in polarization angle, i.e., one oriented horizontally and the other vertically with respect to the stripe of wrinkles. The LD intensity was recorded with the extinction difference between horizontally and vertically polarized light, encompassing both the absorption and forward scattering components along the z-axis while excluding any backward scattering (reflection). Their electrical field maps were recorded with frequency profile monitors placed at the middle of z height of models with a wavelength determined by the maximum LD intensity.

[0140] The refractive index of Ti3C2Tx used for simulation was measured with an ellipsometer on one layer of Ti3C2Tx nanoplatelets LBL assembled on a Si wafer. Using this obtained refraction index, the simulated extinction spectrum matched well with experiments. TheAttorney Docket No.2115-008388-WO-POA refractive index of PDMS and Ag were sourced from prior research. Simulation wavelengths were set in the 300 to 1500 nm range with a refractive index of 1.0003 for the air background.

[0141] Molecular dynamics simulations for Cys-capped MoS2 nanoplatelets. VESTA 3.4.4 software was used to build a MoS2supercell, using the wrinkled structure taken from the Crystallographic Open Database (COD entry 9007660). The supercell was cut in half along c and also along the crystallographic directions [-110], [1-10]. Lowest-coordination sulfur atoms of the MoS2nanoplatelets were replaced by L-Cys zwitterion, with the carboxylate group deprotonated and the amino group protonated. The insert-molecules tool from Gromacs 2022.2 package was used in this step and the resulting structure was then subjected to an initial relaxation of the ligands over frozen Mo and S atoms as follows: (1) two minimization steps were carried out using the steepest descent algorithm until forces reached values below 200 kJ / mol / nm followed by another minimization step using the conjugate gradient algorithm until forces reached values below 100 kJ / mol / nm; (2) the resulting structure was then subjected to a simulated annealing run with initial heating from 100 to 500 K during 2 ns, followed by 1 ns at a temperature of 500 K and then cooling to 100 K during another 2 ns; and (3) the resulting structure was then subjected to another minimization procedure similar to step (1). These classical procedures were performed in a vacuum. Lennard-Jones charges and bonded parameters for the ligands were taken from the LigParGen server. Lennard-Jones parameters for Mo and S atoms from the nanostructure were taken from Liu et al., “Interpretable molecular models for molybdenum disulfide and insight into selective peptide recognition,” Chem. Sci.11, 8708–8722 (2020), the relevant portions of which are incorporated herein by reference and generic atomic partial charges were assigned to these atoms to deliver a neutral system.

[0142] After classical minimization with frozen Mo and S atoms, quantum chemistry calculations were performed at the GFN1-xTB level using the xTB 6.4.0 software. All calculations were performed using the analytical linearized Poisson-Boltzmann model for water and an electronic temperature of 1000 K. Firstly, a full geometry optimization step was carried until an energy variation below 5×10⁻⁶ Eh and a gradient below 1×10⁻³ Eh / Bohr was reached. The resulting structure was then taken for a 40 ps molecular dynamics (MD) run at the NVT ensemble (300 K) with a 0.5 fs timestep. All Mo-S bonds were constrained at the optimized values with a 1.0 Eh / bohr² force constant to avoid large structural deformations.

[0143] The CD spectrum was computed for the final structure considering the analytical linearized Poisson-Boltzmann solvation model for water and excitations up to 7.0 eV and the spectra were obtained using Gaussian broadening with a full width at half maximum of 1.2 eV. The spectrum for the D-Cys enantiomer system was obtained by mirroring the spectrum calculatedAttorney Docket No.2115-008388-WO-POA for the L-Cys system. All calculations were performed using the xTB / sTDA formalism, as implemented in the XTB4STDA 1.0 and sTDA 1.6.1 software. Besides simulating the CD spectra, the sTDA calculations also provide information about the electronic reorganization taking place for each excited state j with respect to the ground state by analyzing the average change in the Löwdin charge population P on each atom i (Eq.3). Such population variations may be converted to changes in the electric charges (q) by taking their negative (Eq. 4) since an increase in the electronic population on an atom decreases its partial atomic charge.

[0144] ∆^ ^ ^= ^^ ^− ^^^(Eq.3)

[0145] ∆ ^ ^= −∆^^ ^ (Eq.4)

[0146] The number of individual excitations is too large to allow the proper analysis of each transition, so the charge differences obtained from the Löwdin populations were averaged out over 5 nm wavelength intervals in the range from 200 to 400 nm. Instead of analyzing the electronic populations, electrostatic potential arising from the charge polarization on a solvent- accessible surface around the Cys-MoS2 structure is computed, which is more representative of the effects of interest (the surface polarization of the nanoplatelets upon illumination). These electrostatic potential variations were decomposed into contributions arising from the inorganic nanoplatelets (both Mo and S contributions) and Cys ligands to identify the charge transfer character between these unities along the spectral window.

[0147] Calculation of chirality indexes for Cys-functionalized MoS2nanoplatelets. The chirality index of different structures from the MD simulation was quantified using both Hausdorff and Osipov-Pickup-Dunmur metrics with Fortran codes. Calculations were performed for the final L-Cys-capped MoS2full structure and considered subsets containing only its MoS2atoms and only its L-Cys atoms. For comparison purposes, calculations were also performed considering the initial MoS2 nanoplatelets before functionalization of both L-Cys and D-Cys, isolated molecules after classical energy minimization, and an ensemble of 100 structures along a 1 ns-long classical stochastic dynamics at 300 K.

[0148] Characterization protocols for materials. CD and extinction spectra were acquired using a JASCO J-1700 CD spectrophotometer with the g-factors to record the anisotropy of circular polarization, which was calculated with the following equation: !− factor =&' / ()*+,-*+^, × 0123^ (Eq.5) where the units of mdeg and a.u. were used to scale CD and extinction intensities. The switch from photomultiplier tube (190–800 nm) to InGaAs (800–1300 nm) detector results in the discontinuity at 800 nm for the intensities of CD, extinction and g-factor spectra obtained by JASCO J-1700, while not significantly influencing the spectral shape. MMP CD, other multipleAttorney Docket No.2115-008388-WO-POA optical polarization elements in the Mueller matrix, and polarization mapping were obtained with a Mueller matrix polarimeter by Hinds Instrument. Besides “true” isotropic CD, both the mentioned instruments measure CD originating from the light interacting with LD- and LB-active strata. This optical activity can be referred to as “apparent” CD; this term only underscores the difference with what other publications referred to as “true” or isotropic CD originating from the mirror asymmetry of (nano)structures freely dispersed in the media and CD originating from other polarization components. The “apparent” CD is not an artifact, as it is sometimes referred to in the literature since it does change the circular polarization state of circularly polarized light when the light passes through an anisotropy medium. It is a different optical process in comparison to “true” CD as shown in FIGS. 5A–5B. The sum of all CD components is detected by spectropolarimeters. In FIG. 5A, differential transmittance for LH and RH circularly polarized light passing through M1-composites with LB and LD strata is shown. In FIG.5B, the differential transmittance and attenuation of the LH and RH circularly polarized light with conventional chiral structures of different types is shown for comparison.

[0149] Circularly polarized light emission (CPLE) was measured with a JASCO CPL-300 spectrophotometer with gem to record the anisotropy of circular polarization in the light emission, which was calculated with the following equation:where CPLE adopts a unit of mdeg, and direct current, DC, is the fluorescence intensity recorded by photomultiplier tubes with a unit of V. Near-infrared CPLE spectra were recorded by OLIS NIR CPL Solo spectrometer with Hamamatsu thermoelectric cooled near-infrared photomultiplier tubes from the range of 900 to1700 nm.

[0150] The mechanical properties of Ti3C2Tx composite film were measured with nanoindentation by Hysitron TI 950 Nanoindenter (Bruker, USA) with a Berkovich probe on a silicon wafer. For the measurement of mechanical ruggedization of Ti3C2Tx composites on soft PDMS strips with a height of 1 cm, a spherical probe with a diameter of 50 micrometers was used for the indentation test. After every 5 or 10 bilayers of Ti3C2Tx-PDDA deposition, nanoindentation was performed until 80 bilayers. All measurements were conducted in a displacement control mode with a peak displacement of 10, 30, and 50 nm for the composites with a total LBL thickness of 340 nm on a silicon wafer and 1 micrometers for the composites on PDMS substrates.6 random points in an area of 5 × 5 mm were indented during the measurement. Reduced modulus (Er) and hardness were fitted from the force-displacement curves, while Young’s modulus (E) was calculated with the following equation:Attorney Docket No.2115-008388-WO-POA / ( / =>?) ( / =>A?) ;<= ; + ;A(Eq.7) where Er is the fitted reduced modulus, ν is the Poisson’s ratios of PDMS (0.5) and Ti3C2Tx (0.227), νi (0.2) is the Poisson’s ratio of diamond indenter with corresponding Young’s modulus (Ei) of 1220 GPa, and E is Young’s modulus of the sample.

[0151] The refraction index of Ti3C2Tx was measured with an ellipsometer of J.A. Woollam M-2000 VASE at three angles of 50°, 60°, and 70° to one layer of Ti3C2Tx nanoplatelets LBL assembled on a Si wafer. The final refraction index used for simulation was averaged over the three angles. SEM images were taken by FEI Nova 200 Nanolab Dual Beam SEM and FEI Helios NanoLab 650 dual-beam SEM with an acceleration voltage of 5 kV and a current of 0.4 nA. AFM images were taken with a Veeco Dimension Icon AFM system with Bruker probes of RTESPA-150 and analyzed with NanoScope Analysis 2.0. X-ray Photoelectron Spectroscopy (XPS) spectra were obtained with the Kratos Axis Ultra spectrometer. The zeta-potential and hydrodynamic diameter of nanoplatelets were measured by a Zetasizer Nano ZSP (Malvern Instruments Ltd., GB). Results are reflected below in Tables 1 –3.Attorney Docket No.2115-008388-WO-POA Table 1. Chirality indexes of Cys functionalized MoS2nanoplatelets quantified with both HCM and OPD.a. Averages values obtained from frames 1–100 of classical MD. b. This line corresponds to averages over all ligands from the final structure.Attorney Docket No.2115-008388-WO-POA Table 2. Groove intervals and depths of M1-composites of Ti3C2Txfabricated with different wrinkled stamps.Attorney Docket No.2115-008388-WO-POA Table 3. Circularly polarized emissionafor LH polarized flame with polarization generation modulated by M2-composites of Ti3C2Tx incorporated with different layers of Ag nanowires.a. The polarization anisotropy, quantified by the difference in the intensity profile of images under the filtering of LH and RH Ti3C2Txcomposites, (LH-RH) / (LH+RH), exhibited a linear dependence with the addition of Ag nanowire layers (FIG. 4D). With five layers of Ag nanowires, the ratio of LH and RH emission for the LH polarized flame reached 38:62 as recorded by the gemof flame, while a maximum polarization anisotropy of (48 ± 1.2)% was achieved with circular polarization filters of M2-composites from Ti3C2Tx.Attorney Docket No.2115-008388-WO-POA

[0154] Effect of nanoplatelet sizes on the optical activity of composites was investigated. The size of nanoplatelets plays a role in the nanoscale structure of composites, their thermal robustness and their optical polarization effect. Overall, the thicker and more rigid the nanoplatelets are, the smaller the optical effects. It was also found that a size match between nanoplatelets and grooves is important for obtaining uniform composites with strong optical polarization. To be more specific, a summary of the effect of nanoplatelet size on the structure and optical activity of obtained nanocomposites is provided below.

[0155] M1-composites of Ti3C2Tx. If the size of the nanoplatelets exceeds the dimensions of the grooves, the composite films become less uniform, resulting in weak polarization rotation. For Ti3C2Txnanoplatelets, the average size of nanoplatelets may be less than about 1.1 micrometers, in certain variations.

[0156] M1-composites of MoS2. Nanoplatelets of MoS2 with an average size and height of 160 and 20 nm, respectively, are more rigid than those from Ti3C2Tx. The grooves in PET are filled after five LBL deposition cycles, resulting in the absence of LD and a weak polarization rotation. The “true” 2D monolayers of MoS2 form a well-integrated composite with an intense optical polarization.

[0157] M2-composites of Ti3C2Tx. Thin monolayer platelets with conformal adhesion to the substrate result in composites with stronger optical effects compared to larger and thicker nanoplatelets with multiple stacks of Ti3C2Tx-PDDA bilayers. The thick large platelets are deposited randomly, making it challenging to have uniform composite structures with strong polarization rotation.

[0158] Further, the effect of bilayer numbers on optical activities was investigated. The number of bilayers determines not only the thickness of layers, for example, comprising Ti3C2Tx nanoplatelets, but also the morphology of the composite films. Consequently, the number of bilayers affects LD, LB, and CD responses of the optical elements. For clarity and adequate benchmarking, the role of bilayer number for M1- and M2-composites based on MMP was quantified and summarized below.

[0159] Effect of bilayer numbers on LB. A large part of LB originates from the substrates of PET and stretched PDMS. It decreases with increasing numbers of Ti3C2Tx-PDDA bilayers, due to the decrease in transmittance caused by the additional layers. This effect is observed for both M1- and M2-composites.

[0160] Effect of bilayer numbers on LD. LD originates from Ti3C2Tx-PDDA bilayers and increases with increasing number of Ti3C2Tx-PDDA bilayers. In the case of M1-composites, both the experiments and FDTD simulations indicate that LD gradually increased and then saturatedAttorney Docket No.2115-008388-WO-POA for increasing stack of Ti3C2Tx-PDDA bilayers owing to the decrease of transmittance as a result of the increase of reflection. While for M2-composites, LD initially increased over the first 4 bilayers, but subsequently declined rapidly because of the expanded intervals between wrinkles under their robust mechanical strength that hindered composite flattening during the untwisting process.

[0161] Effect of bilayer numbers on CD. CD exhibited a corresponding change withbilayer numbers and displayed a linear dependency with the values of LB ∙ LD′, i.e., CD ∝ LB ∙LD^.

[0162] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

Attorney Docket No.2115-008388-WO-POA CLAIMS What is claimed is:

1. An optically active nanocomposite material comprising: a textured substrate; and a multilayer optic stack disposed on the textured substrate, wherein the multilayer optic stack comprises at least one layer comprising a plurality of nanoplatelets, wherein the optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD), has an optical asymmetry g-factor of greater than or equal to about 1, and is stable to a temperature of greater than or equal to about 250°C.

2. The optically active nanocomposite material of claim 1, wherein the multilayer optic stack comprises a plurality of layers in addition to the at least one layer comprising the plurality of nanoplatelets, wherein the multilayer optic stack defines a first axis for linear birefringence (LB) and a second axis that defines linear dichroism (LD), wherein an angular offset is defined between the first axis and the second axis.

3. The optically active nanocomposite material of claim 2, wherein the multilayer optic stack further comprises a layer comprising a plurality of anisotropic nanoparticles.

4. The optically active nanocomposite material of claim 3, wherein the plurality of anisotropic nanoparticles is selected from the group consisting of: nanowires, nanorods, nanotubes, and combinations thereof.

5. The optically active nanocomposite material of claim 3, the plurality of anisotropic nanoparticles comprises nanowires comprising silver.

6. The optically active nanocomposite material of claim 2, wherein the multilayer optic stack further comprises a layer comprising an achiral dye.

7. The optically active nanocomposite material of claim 2, wherein the textured substrate is in a deformed state when the plurality of layers are deposited thereon and can transition from the deformed state to a relaxed state to define a plurality of wrinkles or cracks in the multilayer optic stack.

8. The optically active nanocomposite material of claim 1, wherein the optically active nanocomposite material further displays circular dichroism (CD).

9. The optically active nanocomposite material of claim 1 that is stable to the temperature of greater than or equal to about 300 °C.

10. The optically active nanocomposite material of claim 1, wherein the plurality of nanoplatelets comprises a material selected from the group consisting of: transition metal chalcogenides, two-dimensional MXene carbides or nitrides represented by a general formulaAttorney Docket No.2115-008388-WO-POA Mn+1XnTx, where M represents a transition metal, X represents carbon or nitrogen, n can be from 1 to 4, and Tx represents terminations on an outmost transition metal layer surface, nanocarbons, and combinations thereof.

11. The optically active nanocomposite material of claim 1, wherein the plurality of nanoplatelets comprises a material selected from the group consisting of: molybdenum disulfide (MoS2), tungsten disulfide (WS2), rhenium disulfide (ReS2), molybdenum ditelluride (MoTe₂), tungsten ditelluride (WTe₂), niobium disulfide (NbS₂), niobium diselenide (NbSe₂), tantalum disulfide (TaS₂), tantalum diselenide (TaSe₂), and rhenium diselenide (ReSe₂), titanium carbide (Ti3C2Tx) where x ranges from 0 to 2, vanadium carbide (V₂C), niobium carbides (Nb₂C, Nb₄C₃), molybdenum carbide (Mo₂C), titanium carbonitride (Ti₃CN), chromium carbide (Cr₂C); titanium nitride (Ti₄N₃), and vanadium carbide (V₄C₃), graphene, graphene oxide (GO), reduced graphene oxide (rGO), and carbon nitride (C₃N₄), and combinations thereof.

12. The optically active nanocomposite material of claim 1, wherein the multilayer optic stack comprises at least one bilayer that comprises the plurality of nanoplatelets in a first layer and further comprises poly(diallyldimethylammonium chloride) (PDDA) in a second layer.

13. The optically active nanocomposite material of claim 1, wherein the textured substrate has a diagonal pattern relative to a major dimension defined therein.

14. The optically active nanocomposite material of claim 13, wherein the diagonal pattern comprises a plurality of grooves.

15. The optically active nanocomposite material of claim 1, wherein the plurality of nanoplatelets has an average maximum dimension of greater than or equal to about 100 nm to less than or equal to about 500 nm.

16. A resonator cavity comprising the optically active nanocomposite material of claim 1. 17 An optically active nanocomposite material comprising: a multiple layer optic stack comprising a plurality of nanoplatelets, wherein the optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD) and has an optical asymmetry g-factor is greater than or equal to about 1 and is stable to a temperature of greater than or equal to about 250 °C.

18. A method for forming an optically active nanocomposite material comprising: applying a first charged material having a first polarity to a substrate having a second polarity opposite to the first polarity; applying a second charged material having the second polarity over the first charged material in a layer-by-layer process, wherein the first charged material and the secondAttorney Docket No.2115-008388-WO-POA charged material are distinct from one another and selected from a polymer and a plurality of nanoplatelets; and repeating the applying the first charged material and the applying the second charged material to form the optically active nanocomposite material comprising multiple layers comprising the polymer and the plurality of nanoplatelets, wherein the optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD) and has an optical asymmetry g-factor is greater than or equal to about 1.

19. The method of claim 18, wherein the substrate is under an applied force and in a first twisted state during the applying the first charged material, during the applying the second charged material, and during the repeating and the method further comprises permitting the substrate to relax from the first twisted state to a second relaxed state to facilitate at least one of wrinkling, crackling, or buckling of the optically active nanocomposite material comprising multiple layers.

20. The method of claim 18, wherein the substrate is a textured substrate that comprises a plurality of grooves.

21. The method of claim 20, wherein the plurality of grooves are formed by imprinting the substrate or a layer disposed on the substrate with a stamp via soft lithography.

22. The method of claim 20, wherein the textured substrate has a diagonal pattern relative to a major dimension defined therein and the diagonal pattern comprises a plurality of grooves.

23. The method of claim 18, wherein the first charged material is the polymer that is positively-charged and the second charged material is the plurality of nanoplatelets that is negatively-charged.

24. The method of claim 18, wherein the first charged material comprises poly(diallyldimethylammonium chloride) (PDDA) and the second charged material comprises the plurality of nanoplatelets.

25. The method of claim 18, wherein the plurality of nanoplatelets comprises a material selected from the group consisting of: transition metal chalcogenides, two-dimensional MXene carbides or nitrides represented by a general formula Mn+1XnTx, where M represents a transition metal, X represents carbon or nitrogen, n can be from 1 to 4, and Txrepresents terminations on an outmost transition metal layer surface, nanocarbons, and combinations thereof.

26. The method of claim 18, wherein the plurality of nanoplatelets comprises a material selected from the group consisting of: molybdenum disulfide (MoS2), tungsten disulfide (WS2), rhenium disulfide (ReS2), molybdenum ditelluride (MoTe₂), tungsten ditelluride (WTe₂),Attorney Docket No.2115-008388-WO-POA niobium disulfide (NbS₂), niobium diselenide (NbSe₂), tantalum disulfide (TaS₂), tantalum diselenide (TaSe₂), and rhenium diselenide (ReSe₂), titanium carbide (Ti3C2Tx) where x ranges from 0 to 2, vanadium carbide (V₂C), niobium carbides (Nb₂C,molybdenum carbide (Mo₂C), titanium carbonitride (Ti₃CN), chromium carbide (Cr₂C); titanium nitride (Ti₄N₃), and vanadium carbide (V₄C₃), graphene, graphene oxide (GO), reduced graphene oxide (rGO), and carbon nitride (C₃N₄), and combinations thereof.

27. The method of claim 18, further comprising applying a layer comprising a third charged species comprising a plurality of anisotropic nanoparticles.

28. The method of claim 27, wherein the anisotropic nanoparticles are selected from the group consisting of: nanowires, nanorods, nanotubes, and combinations thereof.

29. The method of claim 27, further comprising aligning the plurality of anisotropic nanoparticles on the substrate by one or more alignment processes selected from the group consisting of: high-speed spraying under shear force, alignment by an external electric field, alignment by an external magnetic field, Langmuir-Blodgett alignment technique, and combinations thereof.

30. The method of claim 18, further comprising applying a layer comprising a third charged species comprising an achiral dye.

31. The method of claim 18, wherein the optically active nanocomposite material further displays circular dichroism (CD).

32. A method for forming an optically active nanocomposite material comprising: applying a plurality of nanoplatelets to a surface of a polymeric substrate to define a texture comprising a plurality of grooves, wherein the applying includes one or more processes selected from the group consisting of: microcontact printing by pressing a stamp having the plurality of nanoplatelets disposed thereon onto the surface, ink jet printing the plurality of nanoplatelets onto one or more target regions of the surface, screen printing, spin coating, or both screen printing and spin coating the plurality of nanoplatelets onto the surface, applying the plurality of nanoplatelets to one or more exposed regions on the surface having a photolithography treated layer disposed thereon, and combinations thereof to form the optically active nanocomposite material having an optic layer comprising the plurality of nanoplatelets disposed over the polymeric substrate, wherein the optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD) and has an optical asymmetry g-factor is greater than or equal to about 1.

33. A method for controlling chirality of an optically active nanocomposite material, the method comprising:Attorney Docket No.2115-008388-WO-POA directing at least one of: (i) an external electric field, (ii) an external magnetic field, or (i) and (ii) towards the optically active nanocomposite material to modify a circular dichroism (CD) exhibited by the optically active nanocomposite material, wherein the optically active nanocomposite material comprises a textured substrate and a multilayer optic stack disposed on the textured substrate, wherein the multilayer optic stack comprises at least one layer comprising a plurality of nanoplatelets, wherein the optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD), has an optical asymmetry g-factor of greater than or equal to about 1, and is stable to a temperature of greater than or equal to about 250°C.