阅读说明：本技术 通过液晶具有可变散射的可电控装置及其方法 (Electrically controllable device with variable scattering by liquid crystal and method thereof ) 是由 F·蒙迪欧 于 2021-03-26 设计创作，主要内容包括：本发明涉及一种通过液晶具有可变散射的装置(100),其包括具有第一电极(2)、具有通过聚合物网络进行稳定的液晶的电活性层(3)和第二电极(2')的堆叠体。从称为T1的温度开始,该材料具有称为P的中间相。在大于或等于T1的温度T'下,该堆叠体能够在可见光范围内具有至少三种稳定且可逆的散射状态和一种可变颜色。本发明还涉及该装置的制备。(The invention relates to a device (100) with variable scattering by liquid crystals, comprising a stack with a first electrode (2), an electroactive layer (3) with liquid crystals stabilized by a polymer network, and a second electrode (2'). Starting from a temperature called T1, the material has a mesophase called P. At a temperature T' greater than or equal to T1, the stack is capable of having at least three stable and reversible scattering states and one variable color in the visible range. The invention also relates to the production of such a device.)

1. An electrically controllable device (100, 200, 300, 400, 500, 600, 700) with variable scattering by liquid crystals, comprising a stack of layers in the following order:

a first electrode (2), in particular on a dielectric substrate, having a first main surface, called connection surface, and a surface, called opposite surface Sb,

-a dielectrically electroactive layer (3) having a main face called "connection surface side" and a main face called the opposite face a2, made of a material comprising:

the liquid crystal(s) of the liquid crystal(s),

polymers forming a polymer network through which the liquid crystal is stabilized,

a second electrode (2') having a main surface called second connection surface and a surface called opposite surface Sc on the side of plane A2, in particular on a dielectric support,

the electroactive layer is visible due to the transparency at the side of the first electrode and/or at the side of the second electrode,

characterized in that the material has, starting from a temperature called T1, a mesophase called P, wherein the material comprises a set of domains, in particular sub-centimeter domains, said domains comprising two-dimensional topological defects,

characterised in that, at a temperature T' greater than or equal to T1, the stack is capable of having at least three scattering states in an operating range which includes all or part of the visible range,

the first state is the most scattering,

the second state is scattering and less scattering than the first state,

and the third state is transparent or scattering and less scattering than the second state,

the three states are switchable and reversible,

at least two of the three states are obtained by applying an electric field between the first and second electrodes,

and in that the material comprises at least one dichroic dye having an absorption wavelength or even an absorption band comprised in said working range, and in that a first scattering state is coloured, having a given colour C0 defined by a brightness L x 0, and a second, less scattering state having a given colour C1, distinguished from C0, defined by a brightness L1, distinguished from L x 0.

2. Electrically controllable device with variable scattering by liquid crystals according to the preceding claim, characterized in that a first colored scattering state is achievable in the absence of said applied electric field, a second and a third state are achievable in the presence of said applied electric field, the applied electric field being preferably an alternating electric field, the second colored scattering state being obtained for a voltage V1, the third colored scattering state being obtained for a voltage V2 greater than V1, and L1 being greater than L0, in particular L1-L0 being at least 1, even preferably the third state being the lowest scattering among the three states also having a color C2 differentiated from C1 and C0 defined by a brightness L2 differentiated from L1 and L0; in particular, L2 is greater than L1 and greater than L0.

3. Electrically controllable device according to any of the preceding claims, having variable scattering by liquid crystals, characterized in that said electric field is alternating and at T' said stack has a diffuse transmission TD and/or a haze H decreasing with voltage at least up to a voltage threshold value and a color having a brightness L decreasing or increasing with voltage at least up to said voltage threshold value.

4. Electrically controllable device with variable scattering by liquid crystals according to any of the preceding claims, characterized in that the stack has:

at least 30%, even 50%, or 70% of the relative difference in% between H0 and Hv, H0 and Hv being in absolute value, where Hv is the haze value under an electric field, H0 is the haze value without an electric field, in particular H0 is greater than Hv,

-and/or a relative difference in% between TL0 and TLv of at least 5% or even 10%, where TLv is the value of the light transmission under an electric field, and TLv is the value of the light transmission without an electric field,

-and/or a relative difference in% between AL0 and ALv of at least 5%, even 10% or 20%, AL0 and ALv being in absolute value form, where ALv is the absorption value under an electric field and AL0 is the absorption value without an electric field, in particular AL0 is greater than ALv.

5. An electrically controllable device having variable scattering by liquid crystals according to any of the preceding claims, characterized in that it comprises at least one linear polarizer having a polarization axis in a plane parallel to plane a 1.

6. Electrically controllable device with variable scattering by means of a liquid crystal according to any of the preceding claims, characterized in that the mesophase P is not a smectic phase, in particular a nematic phase.

7. Electrically controllable device with variable scattering by liquid crystals according to any of the preceding claims, characterized in that said material has a further mesophase P 'at a temperature below T1, said mesophase P being further away from said crystalline phase than said mesophase P', in particular mesophase P is a nematic phase, optionally twisted.

8. Electrically controllable device with variable scattering by liquid crystals according to any of the preceding claims, characterized in that the domain of the mesophase P is a domain remaining from another mesophase P ', and in particular phase P is further away from the crystalline phase than mesophase P', and preferably is a nematic phase, optionally twisted.

9. An electrically controllable device having variable scattering by liquid crystals according to any of the preceding claims, characterized in that said domains of mesophase P are the domains remaining from another mesophase P ', phase P' not being a nematic phase; in particular, the mesophase P' is a smectic phase, and the defects of the mesophase P are smectic phase defects.

10. Electrically controllable device with variable scattering by liquid crystals according to any of the preceding claims, characterized in that the domains of the mesophase P are the domains remaining from another mesophase P', and in particular phase P is a nematic phase.

11. Electrically controllable device with variable scattering by means of liquid crystals according to any of the preceding claims, characterized in that said domains can resemble smectic focal conic domains, in particular toroidal, non-toroidal, parabolic, semi-cylindrical, sector-shaped.

12. Electrically controllable device with variable scattering by means of liquid crystals according to any of the preceding claims, characterized in that it comprises:

-in contact with face a1, a first surface anchoring layer of said liquid crystal, capable of anchoring, in the absence of said applied electric field, at least part of the liquid crystal in contact with it, along a first, preferably planar, orientation, the first anchoring layer preferably being transparent, in particular having a thickness E at most of microns or even sub-microns₁，

-in contact with face a2, a second surface anchoring layer, in particular normal or degenerate planar, capable of orienting, in the absence of said applied electric field, a portion of the liquid crystal in contact with it in a second orientation, in particular similar to or distinct from the first orientation, preferably transparent and having a thickness E 'of at most microns, even sub-microns'₁。

13. Electrically controllable device with variable scattering by means of liquid crystals according to the preceding claim, characterized in that:

the first anchoring layer is a unidirectional or degenerate planar anchoring and the second anchoring layer is a preferably normal or degenerate planar anchoring,

-or the first anchoring layer is a dielectric layer, in particular a polymer dielectric layer, and/or the second anchoring layer is a dielectric layer, in particular a polymer dielectric layer, or an air or gas cavity.

14. Electrically controllable device with variable scattering by liquid crystals according to any of claims 1 to 13, characterized in that said dielectric substrate (1) is transparent and carries on the Sb side a first electrode which is transparent and is selected from a glass sheet or a transparent polymer sheet with an optional scratch-resistant layer, and/or the dielectric support (1') is transparent and carries on the S' b side a second electrode which is transparent and is selected from a glass sheet or a transparent polymer sheet with an optional scratch-resistant layer.

15. Electrically controllable device with variable scattering by liquid crystals according to any of claims 1 to 14, characterized in that the dielectric substrate (1) is transparent and carries on the Sb side a first electrode which is transparent and comprises a first glass sheet which is laminated on the Sb side to another glass sheet by means of a thermoplastic lamination interlayer and/or the dielectric support (1') is transparent and carries on the Sb side a second electrode which is transparent and comprises a glass sheet which is laminated on the S' b side to another glass sheet by means of a thermoplastic lamination interlayer occupying all or part of the surface of the bent and/or quenched first glass sheet.

16. An electrically controllable device having variable scattering by liquid crystals according to any of the preceding claims, characterized in that it comprises a laminated glazing comprising:

-a first additional glass sheet (8),

-a thermoplastic laminating interlayer, in particular EVA or PVB,

-a second additional glass sheet (8') or plastic sheet,

the inner main faces of the first and second additional glass sheets, called F2 and F3, face each other, the stack being between the faces F2 and F3, preferably in a laminated interlayer, in particular with a substrate, even a support, of polymer, occupying all or part of the surface of the first sheet.

17. A method of making an electrically controllable device having variable scattering by liquid crystal, in particular according to any of the preceding claims, comprising the steps of:

providing a first electrode, in particular on a dielectric substrate,

providing a second electrode, in particular on a dielectric support,

-providing a mixture comprising:

at least one polymer precursor, in particular mesogenic or non-mesogenic,

liquid crystals comprising at least a first liquid crystal, in particular non-polymerizable, having an intermediate phase P, and optionally at least a second liquid crystal,

dichroic dyestuffs, especially mesogenic or non-mesogenic,

if necessary, a polymerization initiator, preferably a photoinitiator,

TA is the transition temperature between mesophase P and mesophase P 'of the mixture, below TA the mixture has mesophase P' and from TA has mesophase P,

-forming a stack of layers between the first and second electrodes, comprising forming from said mixture an electroactive layer made of a material comprising said liquid crystal and a dichroic dye stabilized by a polymer network, said forming comprising polymerizing, preferably by photopolymerization, preferably under uv light, said one or more precursors producing said polymer network at a temperature Ti less than TA.

18. Method for producing an electrically controllable device with variable scattering by liquid crystals according to the preceding claim, characterized in that said first liquid crystal has an intermediate phase P 'below the temperature TA, said first liquid crystal having a transition temperature Tp between the intermediate phase P and the intermediate phase P', TA preferably being less than or equal to Tp.

19. Method according to any of the preceding method claims for manufacturing an electrically controllable device with variable scattering, characterized in that the forming of the electroactive layer comprises bringing the mixture into contact with a first and a second liquid crystal surface anchoring layer, in particular comprising:

depositing a layer by a liquid route, or providing an element, such as a submillimeter membrane, connected to a first electrode,

depositing a layer by liquid route, or providing an element, such as a submillimeter membrane connected to a second electrode, or creating a gas cavity, such as an air cavity, between the second electrode and the mixture.

20. The process according to any one of the preceding process claims for manufacturing an electrically controllable device with variable scattering, characterized in that it comprises a step of laminating said stack between two glass sheets, in particular curved, by means of a polymer lamination interlayer, in particular thermoplastic, such as PVB or EVA, comprising one or more sheets, in particular laminated at a temperature of at most 140 ℃ or even at most 120 ℃.