Liquid crystal elastomer composition

Abstract

The illumination system includes a protective LCE layer, which is positioned relative to a light source of the illumination system such that light emitted from the light source passes through the protective LCE layer. The light source can be any of a variety of light sources, including an LCD display, an LED, an array of LEDs, etc. In some embodiments, the protective LCE layer can be formed from a monodomain LCE. In some embodiments, the protective LCE layer can be formed from a polydomain LCE.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to U.S. Provisional Patent Application No. 63 / 369,776, filed July 29, 2023, the entire disclosure of which is incorporated by reference.

[0002] The present disclosure relates generally to liquid crystal elastomer (LCE) compositions and more particularly, but not by way of limitation, to the use of LCEs as part of displays. [Background technology]

[0003] This section provides background information to facilitate a better understanding of the various aspects of the present disclosure. It should be understood that statements in this section of the specification are to be read in this light, and not as admissions of prior art.

[0004] Flat screen displays are widely used. There are various different types of technologies used to create flat screen displays, including liquid crystal displays ("LCDs"), plasma displays, electroluminescent (EL) displays, field emission displays, and others. While these technologies all function in different ways, each includes a screen that displays an image to the user. Each type of display also includes a display surface, which is typically the outermost layer of the display. The display surface is intended to protect the display's internal components from damage. To function well, the display surface must meet certain performance metrics related to strength and transmittance. Summary of the Invention

[0005] This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor should it be used as an aid in limiting the scope of the claimed subject matter.

[0006] The illumination system includes a protective LCE layer, which is positioned relative to a light source of the illumination system such that light emitted from the light source passes through the protective LCE layer. The light source can be any of a variety of light sources, including an LCD display, an LED, an array of LEDs, etc. In some embodiments, the protective LCE layer can be formed from a monodomain LCE. In some embodiments, the protective LCE layer can be formed from a polydomain LCE.

[0007] In various embodiments, the display surface of the display comprises an LCE sheet. In some embodiments, the LCE sheet comprises a monodomain LCE. In some embodiments, the LCE sheet comprises a polydomain LCE.

[0008] In some embodiments, the LCE sheet is composed of a monodomain LCE and includes the following properties: haze of about 3.34%, transmittance of about 90.7%, sharpness of about 93.99%, and clarity of about 99.01%.

[0009] In some embodiments, the LCE sheet is composed of a monodomain LCE and has a thermal conductivity along the fibers of about 0.33 to about 0.37 W / mK.

[0010] In some embodiments, the LCE sheet is composed of a monodomain LCE and has a cross-fiber thermal conductivity of about 0.16 to about 0.19 W / mK.

[0011] In some embodiments, the LCE sheet is composed of a monodomain LCE and has a thickness of about 0.1 to about 0.115 mm. 2 / s thermal diffusivity along the fiber.

[0012] In some embodiments, the LCE sheet is composed of a monodomain LCE and has a thickness of about 0.07 to about 0.09 mm 2 / s thermal diffusivity across the fiber.

[0013] In some embodiments, the LCE sheet is composed of a polydomain LCE and has a thermal conductivity of about 0.222 W / mK.

[0014] In some embodiments, the LCE sheet is composed of polydomain LCE and has a thickness of about 0.1 to about 0.115 mm 2 / s thermal diffusivity.

[0015] In some embodiments, the LCE sheet is composed of polydomain LCEs and has a thermal conductivity of about 1.9 to about 2.04 MJ / m 3 It has a specific heat of k.

[0016] In various embodiments, an illumination system includes a light source and a protective LCE layer positioned relative to the light source such that light emitted from the light source passes through the LCE layer.

[0017] In some embodiments, the protective LCE layer is composed of a monodomain LCE and includes the following properties: about 3% haze, about 90% transmission, about 93% sharpness, and about 99% clarity.

[0018] In some embodiments, the protective LCE layer is composed of a monodomain LCE and has a along-the-fiber thermal conductivity of about 0.33 to about 0.37 W / mK.

[0019] In some embodiments, the protective LCE layer is composed of a monodomain LCE and has a across-the-fiber thermal conductivity of about 0.16 to about 0.19 W / mK.

[0020] In some embodiments, the protective LCE layer is comprised of a monodomain LCE and has a thickness of about 0.1 to about 0.115 mm. 2 / s thermal diffusivity along the fiber.

[0021] In some embodiments, the protective LCE layer is composed of a monodomain LCE and has a thickness of about 0.07 to about 0.09 mm. 2 / s thermal diffusivity across the fiber.

[0022] In some embodiments, the protective LCE layer is composed of a polydomain LCE and has a thermal conductivity of about 0.222 W / mK.

[0023] In some embodiments, the protective LCE layer is comprised of a polydomain LCE and has a thickness of about 0.1 to about 0.115 mm. 2 / s thermal diffusivity.

[0024] In some embodiments, the protective LCE layer is composed of a polydomain LCE and has a thermal conductivity of about 1.9 to about 2.04 MJ / m 3 It has a specific heat of k.

[0025] In some embodiments, the light source is selected from the group consisting of an LCD display, an OLED display, a mobile device, a table, a smartwatch, an LED, and an array of LEDs.

[0026] In some embodiments, the light source is a foldable display.

[0027] A more complete understanding of the subject matter of this disclosure can be obtained by reference to the following detailed description in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0028] [Figure 1A] FIG. 1 shows mesogen alignment in a polydomain main-chain LCE. [Figure 1B] FIG. 1 shows mesogen alignment in a monodomain main-chain LCE. [Figure 2(a)] FIG. 1 shows a two-step thiol-acrylate reaction for synthesizing and programming LCEs and illustrates the chemicals used for the synthesis. [Figure 2(b)]FIG. 1 shows a two-step thiol-acrylate reaction for synthesizing and programming an LCE, illustrating the polydomain state after the Michael addition reaction. [Figure 2(c)] FIG. 1 shows a two-step thiol-acrylate reaction to synthesize and program an LCE, with stretching used to orient the mesogens into a monodomain. [Figure 2(d)] FIG. 1 shows a two-step thiol-acrylate reaction to synthesize and program an LCE, showing an anisotropic monodomain after UV crosslinking. [Figure 3A] 1 is a graph of stress versus strain for axial loading of an LCE sample, according to an embodiment of the present disclosure. [Figure 3B] 1 is a graph of stress versus strain for lateral loading of an LCE sample, according to an embodiment of the present disclosure. [Figure 4A] 1 is a graph of load versus displacement for an LCE sample, according to an embodiment of the present disclosure. [Figure 4B] 1 is a graph of elastic modulus versus displacement for an LCE sample, according to an embodiment of the present disclosure. [Figure 5] FIG. 1 is a schematic diagram of a touchscreen display having a protective LCE layer, according to an embodiment of the present disclosure. [Figure 6] 1 is a schematic diagram of a light source having a protective LCE layer according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0029] It should be understood that the following disclosure provides many different embodiments or examples for implementing different features of various embodiments. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not limiting. The section headings used herein are for organizational purposes and should not be construed as limiting the subject matter described. Reference will now be made to more specific embodiments of the disclosure and data providing support for such embodiments. It should be noted, however, that the following disclosure is for illustrative purposes only and in no way limits the scope of the claimed subject matter.

[0030] LCEs are cross-linked polymer networks that exhibit the anisotropic properties of liquid crystals and the elastic behavior of rubber. This combination of properties makes LCEs adaptable for a wide range of applications. This disclosure focuses on the use of LCEs as part of a transmissive display. To demonstrate the effectiveness of LCEs as part of a transmissive display, various properties of LCE samples were tested, including thermal conductivity, thermal diffusivity, specific heat, transparency, transmittance, sharpness, clarity, and stress.

[0031] LCEs are a class of multifunctional polymers that combine network elasticity with liquid crystal ordering. Liquid crystals are composed of rigid aromatic rings known as mesogens. Self-assembly of mesogens results in liquid crystal ordering, which can exist in two states: polydomain and monodomain. Figure 1A shows the polydomain state, in which mesogens 1 are arranged in randomly oriented domains, resulting in significant damping and energy dissipation. Figure 1B shows the monodomain state, in which mesogens 1 are aligned for enhanced strength and are simultaneously mechanically anisotropic. When anchored into a polymer network, the mesogen ordering confers unique capabilities to the material, including the ability for tuned gradients and anisotropy, muscle-like reversible actuation, and extreme energy dissipation compared to conventional hydrogels, rubbers, and elastomers.

[0032] LCE synthesis and preparation are not trivial processes. Main-chain LCEs, defined by direct synthesis of mesogens onto the polymer backbone, exhibit ideal coupling behavior leading to exceptional properties. However, this process has long been a challenge in the field of LCEs. Most researchers use sequential hydrosilylation reactions, which require highly pure materials and careful experimental conditions. To tune the liquid crystal structure into a monodomain, the mesogens must be manually oriented during synthesis. Using hydrosilylation reactions, one technique is to allow the material to gel, stretch the gel to align the mesogens and chains, and then allow the reaction to complete crosslinking of the material. This technique is inherently difficult to repeat. Non-mechanical methods, such as surface alignment and magnetic fields, can also be applied to align the mesogens into a monodomain. These methods must be used for one-step reactions, such as free radical reactions, which cannot be stopped and restarted. Furthermore, these reactions are limited to samples less than 100 μm thick. Recently, we have developed a new technique for creating tailored main-chain LCEs with unprecedented scalability, thermomechanical properties, and control over mesogenic order. Figures 2(a)-2(d) show a two-step thiol-acrylate reaction that can be used to synthesize large LCE samples and tuned to exploit the unique properties of LCEs.

[0033] Tables 1 and 2 below report the thermal conductivity and thermal diffusivity values ​​of monodomain and polydomain LCEs at different temperature points. Thermal conductivity and thermal diffusivity were measured at different temperatures using the equipment and parameters described below, all in accordance with ISO 22007-2. Tests were performed using a Hot Disk® TPS3500. The thickness of the tested LCE samples was 1 mm. Tests included the standard isotropic Hot Disk® method, the anisotropic hot strip method, and the Hot Disk® specific heat capacity method. The following sensor types were used: Hot Strip 5081 (20 mm × 6.4 mm), Hot Disk® 5501 Kapton (radius 6.4 mm), and Hot Disk® 5462 Kapton (radius 3.2 mm).

[0034] TIFF2025528330000002.tif30170

[0035] TIFF2025528330000003.tif29170

[0036] The transparency versus wavelength of monodomain LCE samples was tested. The monodomain LCE samples exhibited greater than 80% transmittance at wavelengths greater than approximately 420 nm and greater than 85% transmittance at wavelengths greater than approximately 450 nm. Additionally, the haze, transmittance, sharpness, and clarity of a 0.75 mm thick monodomain LCE sample were measured using a Rhopoint ID-L Transmission Appearance Meter, yielding a haze of 3.34%, transmittance of 90.7%, sharpness of 93.99%, and clarity of 99.01%. Polydomain LCEs may be useful when low transmittance and light diffusion are desired (e.g., luminaires and decorative lighting).

[0037] 3A and 3B are graphs of stress versus strain for axial and lateral loading, respectively, of a monodomain LCE sample according to an embodiment of the present disclosure. The LCE sample dissipated more energy as the applied strain rate increased, both when loaded axially and laterally. Energy dissipation was nearly an order of magnitude higher when the material was loaded axially compared to when loaded laterally. These test results also demonstrate the impact resistance capabilities of the sample. Thermoplastic polyurethanes are commonly used in applications where impact resistance is important. Table 3 below shows the strain rate for a 0.75 mm thick sample.

[0038] TIFF2025528330000004.tif26170

[0039] These test results indicate that LCEs offer improved impact resistance compared to thermoplastic polyurethanes ("TPUs"). While TPUs are also heat resistant, LCEs are more thermally conductive (and therefore have lower heat resistance) than TPUs. TPUs are widely used for display applications, including flexible displays. LCEs are well suited for use in these applications due to their superior thermal conductivity and impact resistance compared to TPUs. LCEs are soft at temperatures from about 0°C to about 70°C. This makes LCEs applicable to applications at or near ambient temperatures, such as display applications.

[0040] 4A and 4B are graphs of load versus displacement and modulus versus displacement, respectively, for a monodomain LCE sample according to an embodiment of the present disclosure. The LCE sample underwent nanoindentation testing using an Agilent Technologies G200 equipped with an Accutip. The LCE sample exhibited hysteretic behavior during testing, but when given time to recover, the sample fully recovered. Microindentation testing was performed on a 0.75 mm thick LCE sample using a Buehler Micromet II equipped with a diamond Vickers tip.

[0041] FIG. 5 is a schematic diagram of a touchscreen display having a protective LCE layer according to an embodiment of the present disclosure. As discussed above, LCEs have desirable properties compared to conventional materials, making them suitable for use in a wide variety of applications. There are many different types of display technologies, with liquid crystal displays ("LCDs") being one of the most popular. Among LCD displays are various types, including light-emitting diode ("LED") displays and organic LED (OLED) displays. LCD displays typically include various components layered within a housing or frame. Component layers may include, for example, a printed circuit board, polarizers, a light source (e.g., an LED or other light source), color filters, a cover glass, touch sensors, an optically clear adhesive ("OCA"), and the like. The outermost layer of an LCD display is the display surface, which is designed to protect the LCD display's components. In addition to protecting the LCD display's components, the display surface must allow light generated by the LCD display to pass through and be visible to the user. LCEs are well suited for use as a display surface or in combination with an existing display surface because they provide both the protection / strength needed to protect the internal components of the LCD display and the transmittance needed to allow the light produced by the LCD display (i.e., the picture) to pass through and be clearly visible.

[0042] With continued reference to FIG. 5 , an exemplary display 10 is shown schematically. Display 10 is depicted as a touchscreen OLED display. Display 10 includes a cover glass 2, an LCE layer 3, an OCA 4, a polarizer 5, a touch sensor 6, a sealing glass 7, an OLED emitter 8, and a backplane glass 9. Display 10 is merely illustrative; more or fewer layers may be present in various displays. For example, a non-touchscreen display may omit the touch sensor. In other embodiments, display 10 may be a flexible or foldable display. LCEs are well suited for foldable displays given their strength and flexibility. As shown in FIG. 5 , LCE layer 3 is used in conjunction with cover glass 2. LCE layer 3 comprises a monodomain LCE, as monodomain LCEs have greater transmittance than polydomain LCEs. Using LCE layer 3 in conjunction with cover glass 2 enhances the overall strength of the protective layer. In some embodiments, cover glass 2 may be omitted, with LCE layer 3 being the outermost layer. The use of an LCE in display 10, with or without cover glass 2, provides excellent protection for the internal components of display 10 (e.g., printed circuit boards, polarizers, color filters, backlight units, etc.). In various embodiments, display 10 may be incorporated into an LCD television (e.g., home or commercial), a laptop display, a computer monitor display, a mobile device (e.g., a phone or tablet), a smart watch, a vehicle gauge cluster, a head-up display, etc.

[0043] In some embodiments, LCE layer 3 is approximately 50-150 μm thick, but may be thinner or thicker depending on the application. In some embodiments, LCE layer 3 is composed of a monodomain LCE having a haze of approximately 3.34%, a transmittance of approximately 90.7%, a sharpness of approximately 93.99%, and a transparency of approximately 99.01%. In various embodiments, LCE layer 3 is composed of a monodomain LCE having a haze of approximately 1-5%, a transmittance of approximately 85-93%, a sharpness of approximately 90-95%, and a transparency of approximately 95-99%. In some embodiments, LCE layer 3 is composed of a monodomain LCE having a thermal conductivity along the fibers of approximately 0.33-0.37 W / mK. In some embodiments, LCE layer 3 is composed of a monodomain LCE having a thermal conductivity across the fibers of approximately 0.16-0.19 W / mK. In some embodiments, the LCE layer 3 has a thickness of about 0.1 to about 0.115 mm. 2 In some embodiments, the LCE layer 3 is constructed of a monodomain LCE having a thermal diffusivity along the fiber of about 0.07 to about 0.09 mm / s. 2 1 / s. In some embodiments, LCE layer 3 is constructed from a monodomain LCE to have a thermal diffusivity across the fibers of about 0.222 W / mK. In some embodiments, display 10 is constructed from a polydomain LCE to have a thermal conductivity of about 0.1 to about 0.115 mm. 2 In some embodiments, the LCE layer 3 is constructed of a polydomain LCE to have a thermal diffusivity of about 1.9 to about 2.04 MJ / m. 3 It is composed of a polydomain LCE with a specific heat capacity of k.

[0044] FIG. 6 is a schematic diagram of an illumination system 11 having a protective LCE layer 12 according to an embodiment of the present disclosure. The illumination system 11 includes a light source 13, which can be any of a variety of light sources, including an LED or array of LEDs, white light, laser light, arc lamp, etc. In one embodiment, the light source 13 is an LED or array of LED lights. LED lights are sensitive electronic components that benefit from the protection that can be provided by the LCE layer 12. The LCE layer 12 can be formed into a sheet or cover that is fixed in place over the light source 13, or it can be poured in liquid form into a cavity over the light source 13 and cured in place. The LCE layer 12 is positioned relative to the light source 13 so that light emitted from the light source 13 passes through the LCE layer 12. The LCE layer 12 can be formed from a monodomain or polydomain LCE and configured with properties similar to those of the LCE layer 3 described above. The light source 13 can form part of a large LED display (e.g., a television / monitor LED screen, an LED video wall commonly used in commercial applications). LCE layer 12 may be formed from a monodomain LCE if greater transmittance is desired. Polydomain LCEs may be used if it is desired to diffuse the light from light source 13. Diffusing the light can help to better distribute the light within a space and reduce "spot lighting" in the space, and can also provide the aesthetic effect of softening the light distribution.

[0045] While various embodiments of the present disclosure are illustrated in the accompanying drawings and described in the detailed description above, it will be understood that the present disclosure is not limited to the embodiments disclosed herein, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit of the present disclosure as set forth herein.

[0046] The term "substantially" is defined as largely but not necessarily entirely specified, as understood by one of ordinary skill in the art. In any disclosed embodiment, the terms "substantially," "approximately," "nearly," and "about" can be substituted with "within [a percentage] of" that specified, where percentage includes 0.1, 1, 5, and 10 percent.

[0047] The foregoing outlines features of some embodiments so that those skilled in the art may better understand aspects of the present disclosure. Those skilled in the art will appreciate that they can readily use the present disclosure as a basis for designing or modifying other processes and structures to carry out the same purposes and / or achieve the same advantages of the embodiments introduced herein. Those skilled in the art will also appreciate that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the present disclosure. The scope of the present invention is to be determined solely by the language of the claims that follow. The term "comprising" in the claims shall mean "including at least," such that the list of recited elements in the claims is an open group. The terms "a," "an," and other singular terms shall include their plural forms unless specifically excluded.

[0048] In particular, conditional language used herein, such as "can," "might," "may," "eg," and the like, unless expressly stated otherwise or understood otherwise within the context in which it is used, is intended to generally convey that certain embodiments include certain features, elements, and / or conditions, while other embodiments do not. Thus, such conditional language does not generally imply that the features, elements, and / or conditions are in any way required by one or more embodiments, or that one or more embodiments necessarily include logic for determining whether or not those features, elements, and / or conditions should be included in or performed in any particular embodiment, with or without authorial input or direction.

[0049] While the above detailed description illustrates, describes, and points out novel features applicable to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the devices or algorithms shown may be made without departing from the spirit of the present disclosure. It will be recognized that the processes described herein may be implemented in forms that do not provide all of the features and advantages described herein, since some features may be used or practiced separately from others. The scope of protection is defined by the appended claims, rather than the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

[0050] While various embodiments of the method and apparatus of the present invention have been illustrated in the accompanying drawings and described in the detailed description above, it will be understood that the invention is not limited to the disclosed embodiments, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit of the invention as described herein.

Claims

1. The display surface of a display, wherein the display surface includes an LCE sheet. The LCE sheet is composed of monodomain LCE and has the following characteristics: Approximately 3% haze, Approximately 90% light transmittance, Approximately 93% sharpness, and Approximately 99% transparency The display surface, including the surface.

2. The display surface according to claim 1, wherein the LCE sheet is composed of monodomain LCE and has a thermal conductivity along the fibers of about 0.33 to about 0.37 W / mK.

3. The display surface according to claim 1, wherein the LCE sheet is composed of monodomain LCE and has a thermal conductivity across the fibers of about 0.16 to about 0.19 W / mK.

4. The LCE sheet is composed of monodomain LCE and is approximately 0.1 to 0.115 mm thick. ２ The display surface according to claim 1, having a thermal diffusivity along the fibers of / s.

5. The LCE sheet is composed of monodomain LCE and is approximately 0.07 to 0.09 mm thick. ２ The display surface according to claim 1, having a thermal diffusivity across fibers of / s.

6. The display surface according to claim 1, wherein the LCE sheet is composed of polydomain LCE and has a thermal conductivity of about 0.222 W / mK.

7. The LCE sheet is composed of polydomain LCE and is approximately 0.1 to 0.115 mm thick. ２ The display surface according to claim 1, having a thermal diffusivity of / s.

8. The LCE sheet is composed of polydomain LCE and has a density of approximately 1.9 to approximately 2.04 MJ / m ３ The display surface according to claim 1, having a specific heat of k.

9. The display surface according to claim 1, wherein the display is an LCD display.

10. The display surface according to claim 1, wherein the display is a mobile device.

11. Light source and A protective LCE layer, which is positioned relative to the light source such that light emitted from the light source passes through the protective LCE layer. Equipped with, The protective LCE layer is composed of monodomain LCE and has the following characteristics: Approximately 3% haze, Approximately 90% light transmittance, Approximately 93% sharpness, and Approximately 99% transparency A lighting system, including a lighting system.

12. The lighting system according to claim 11, wherein the protective LCE layer is composed of monodomain LCE and has a thermal conductivity along the fibers of about 0.33 to about 0.37 W / mK.

13. The lighting system according to claim 11, wherein the protective LCE layer is composed of monodomain LCE and has a thermal conductivity across fibers of about 0.16 to about 0.19 W / mK.

14. The protective LCE layer is composed of monodomain LCE and is approximately 0.1 to 0.115 mm thick. ２ The lighting system according to claim 11, having a thermal diffusivity along the fibers of / s.

15. The protective LCE layer is composed of monodomain LCE and is approximately 0.07 to 0.09 mm thick. ２ The lighting system according to claim 11, having a thermal diffusivity across fibers of / s.

16. The lighting system according to claim 11, wherein the protective LCE layer is composed of polydomain LCE and has a thermal conductivity of about 0.222 W / mK.

17. The protective LCE layer is composed of polydomain LCE and is approximately 0.1 to 0.115 mm thick. ２ The lighting system according to claim 11, having a thermal diffusivity of / s.

18. The protective LCE layer is composed of polydomain LCE and has a density of approximately 1.9 to approximately 2.04 MJ / m ３ The lighting system according to claim 11, having a specific heat of k.

19. The lighting system according to claim 11, wherein the light source is selected from the group consisting of an LCD display, an OLED display, a mobile device, a tablet, a smartwatch, an LED, and an array of LEDs.

20. The lighting system according to claim 11, wherein the light source is a foldable display.

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