# US 9,869,887 B2 · Adaptive liquid crystal structural interface > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,869,887 B2 - Document ID: US9869887B2 - Status: Granted - Kind: B2 - Application number: 14/361,162 - Filed: 2012-11-30 - Published: 2014-10-30 - Granted: 2018-01-16 - Earliest claimed: 2011-11-30 - Assignees: Alphamicron Incorporated - Applicants: Alphamicron Incorporated - Inventors: Bahman Taheri; Ludmila Sukhomlinova; Paul Luchette - Web page: https://patentgrep.com/patent/US9869887B2 ## CPC - G02F 1/0045: {Liquid crystals characterised by their physical properties} - C09K 19/36: Steroidal liquid crystal compounds - C09K 19/586: {Optically active dopants; chiral dopants} - C09K 19/588: {Heterocyclic compounds} - G02F 1/132: {Thermal activation of liquid crystals exhibiting a thermo-optic effect} - C09K 2219/13: used in the technical field of thermotropic switches - G02F 2201/343: cholesteric liquid crystal reflector - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE ## Abstract A structural interface having an adaptive liquid crystal material that is positioned to receive electromagnetic radiation and adapted to reflect a selective band of the received electromagnetic radiation so as to help with cooling of a structure in the summer and/or heating of the structure in the winter. The adaptive liquid crystal material is designed to change its selective reflection band when exposed to an activating temperature or an activating light or both. Depending on the interior and/or exterior conditions, the adaptive liquid crystal material has one or more selective reflection bands with a peak wavelength selected from the following: within a sunlight wavelength span, outside a thermal infrared wavelength span, outside the sunlight wavelength span, or within the thermal infrared wavelength span. The structural interface may be applied to an exterior or interior surface of a structural envelop or be integrated into a structural envelope material. ## Claims ### Claim 1 A structural interface comprising an adaptive cholesteric liquid crystal material positioned to receive electromagnetic radiation and adapted to reflect a selective band of said electromagnetic radiation; wherein the adaptive cholesteric liquid crystal material undergoes a reversible photo-induced or thermal induced change in chirality or both such that it reversibly changes its pitch and thereby its selective reflection band when exposed to an activating temperature or an activating light or both without undergoing phase transition, wherein the cholesteric liquid crystal material comprises a chiral dopant having a helical twisting power, and wherein said helical twisting power changes by 20% or more when exposed to a temperature change of 10° C. or greater, or when exposed to said activating light, or both, and wherein the adaptive cholesteric liquid crystal material has one or more selective reflection bands with a peak wavelength (λmax) selected from: within 400-1000 nm during hot conditions and outside 400-1000 nm during cold conditions; or within 3000-10,000 nm during cold conditions and outside 3000-10,000 nm during hot conditions. ### Claim 2 (depends on 1) The structural interface of claim 1, wherein the activating temperature is an exterior temperature. ### Claim 3 (depends on 1) The structural interface of claim 1, wherein the activating temperature is an interior temperature. ### Claim 4 (depends on 1) The structural interface of claim 1, wherein the activating light has a wavelength in the solar spectrum. ### Claim 5 (depends on 1) The structural interface of claim 1, wherein the cholesteric liquid crystal material has a peak reflection (λmax) within 400-1000 nm during hot conditions and a peak reflection (λmax) within a thermal infrared wavelength span produced by body heat during cold conditions. ### Claim 6 (depends on 1) The structural interface of claim 1, wherein the change in the selective reflection band is in excess of 2000 nanometers (nm). ### Claim 7 (depends on 1) The structural interface according to claim 1, wherein the selective reflection band is at least 20 nanometers (nm) wide. ### Claim 8 (depends on 1) The structural interface according to claim 1, wherein the cholesteric liquid crystal material comprises a mixture of one or more of: a nematic liquid crystal, a smectic liquid crystal, a chiral dopant, a photo-active chiral dopant, an up-converting dye, a polymer, a polymerizable component, and a cholesterol based chiral liquid crystal. ### Claim 9 (depends on 1) The structural interface according to claim 1, wherein the cholesteric liquid crystal material comprises two or more liquid crystal materials with different phase transition temperatures. ### Claim 10 (depends on 1) The structural interface according to claim 1, wherein the cholesteric liquid crystal material has a birefringence greater than 0.03. ### Claim 11 (depends on 1) The structural interface according to claim 1, wherein the cholesteric liquid crystal material comprises mixtures of opposing chirality. ### Claim 12 (depends on 1) The structural interface according to claim 1, wherein said structural interface is selected from one or more of the following: a layer applied to an exterior or interior surface of a structure, a layer applied to a window, integrated into an envelope material, or integrated into a window. ### Claim 13 (depends on 1) The structural interface according to claim 1, further comprising a polarizer. ### Claim 14 A structural interface comprising an adaptive liquid crystal material positioned to receive electromagnetic radiation and adapted to reflect a selective band of said electromagnetic radiation; wherein the adaptive liquid crystal material undergoes a reversible photo-induced change in chirality such that it changes its selective reflection band when exposed to an activating light and reverts to its original chirality when the activating light is removed without undergoing phase transition, and wherein the adaptive liquid crystal material has one or more selective reflection bands with a peak wavelength (λmax) selected from: (a) within 400-1000 nm during hot conditions and outside 400-1000 nm during cold conditions; (b) outside 3000-10,000 nm during hot conditions and within 3000-10,000 nm during cold conditions; or (c) within 400-1000 nm during hot conditions and within 3000-10,000 during cold conditions. ### Claim 15 (depends on 14) The structural interface according to claim 14, wherein the liquid crystal material comprises a mixture of one or more of: a nematic liquid crystal, a smectic liquid crystal, a chiral dopant, a photo-active chiral dopant, an up-converting dye, a polymer, a polymerizable component, and a cholesterol based chiral liquid crystal. ### Claim 16 (depends on 14) The structural interface according to claim 14, wherein the liquid crystal material comprises two or more liquid crystal materials with different phase transition temperatures. ### Claim 17 (depends on 14) The structural interface according to claim 14, wherein said structural interface is a layer applied to an exterior or interior surface of a structure. ### Claim 18 (depends on 14) The structural interface according to claim 14, wherein said structural interface is integrated into or is applied onto a window. ### Claim 19 (depends on 14) The structural interface according to claim 14, wherein the change in the selective reflection band is in excess of 2000 nanometers (nm). ### Claim 20 (depends on 14) The structural interface according to claim 14, wherein the selective reflection band is at least 20 nanometers (nm) wide. ### Claim 21 (depends on 14) The structural interface according to claim 14, wherein the adaptive liquid crystal material has a birefringence greater than 0.03. ### Claim 22 A structural interface comprising an adaptive liquid crystal material positioned to receive electromagnetic radiation and adapted to reflect a selective band of said electromagnetic radiation; wherein the adaptive liquid crystal material undergoes a photo-induced or thermal-induced phase transition, or both, thereby changing its reflection band when exposed to an activating temperature or an activating light or both, wherein the adaptive liquid crystal material has one or more selective reflection bands with a peak wavelength (λmax) selected from one of the following: (a) within 400-1000 nm during hot conditions and outside 400-1000 nm during cold conditions; (b) outside 3000-10,000 nm during hot conditions and within 3000-10,000 nm during cold conditions; or (c) within 400-1000 nm during hot conditions and within 3000-10,000 nm cold conditions. ### Claim 23 (depends on 22) The structural interface according to claim 22, wherein the liquid crystal material comprises a mixture of one or more of: a nematic liquid crystal, a smectic liquid crystal, a chiral dopant, a photo-active chiral dopant, an up-converting dye, a polymer, a polymerizable component, and a cholesterol based chiral liquid crystal. ### Claim 24 (depends on 22) The structural interface according to claim 22, wherein the liquid crystal material comprises two or more liquid crystal materials with different phase transition temperatures. ### Claim 25 (depends on 22) The structural interface according to claim 22, wherein said structural interface is selected from one or more of the following: a layer applied to an exterior or interior surface of a structure, a layer applied to a window, integrated into an envelope material, or integrated into a window. ### Claim 26 (depends on 22) The structural interface according to claim 22, wherein the liquid crystal material undergoes a phase transition between cholesteric and smectic when exposed to a temperature change of 10° C. or greater.