Method for the Preparation of High-Efficient, Tuneable and Switchable Optical Elements Based on Polymer-Liquid Crystal Composites
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Abstract
A homogeneous isotropic mixture of photocurable monomers and/or oligomers, one or more liquid crystals or a liquid crystal mixture, and optionally a photoinitiator is provided that is homogeneous and optically clear within a temperature range of between 15 and 25° C. An optically transparent film of the homogenous isotropic mixture on a substrate or in a space between two substrates is prepared. The optically transparent film is irradiated with an inhomogeneous light field of actinic light such that areas of the film are irradiated while others are not. The intensity is sufficiently low that first areas solely, substantially or mainly composed of photocured polymer are formed, while the liquid crystals or liquid crystal mixture completely, substantially or mainly escapes into second areas that are not or substantially not irradiated. The substrates are removed depending on whether the rigid or flexible film is to be prepared alone or on a substrate.
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Citations
40 Claims
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1-20. -20. (canceled)
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21. A method for the production of a rigid or flexible film, having first areas being solely, substantially or mainly composed of photocured polymer and second areas being solely, substantially or mainly composed of liquid crystals or a liquid crystal mixture wherein, according to alternative (a), the first and second areas alternate in at least a first plane, while the composition of the film is substantially invariable in at least one direction that is angular to the said first plane, or, according to alternative (b), at least one of either the first or the second areas is completely surrounded by the other area, respectively, and the first and second areas are located in a periodic pattern;
- or for the production of an optical element comprising said film disposed on a flat, light transmitting substrate or between two flat substrates, wherein at least one of the two substrates is light transmitting;
the method comprising the steps of;(a) providing a homogeneous and isotropic mixture, comprising at least a first component, consisting of one or more photocurable monomers and/or oligomers, and a second component, consisting of one or more liquid crystals or a liquid crystal mixture, and optionally further comprising a photoinitiator for photopolymerization of the photocurable monomers and/or oligomers, wherein said homogeneous and isotropic mixture is homogeneous and optically clear within a temperature range of at least between 20°
C. to 25°
C., more preferably of at least between 15°
C. and 25°
C.,(b) preparing an optically transparent film of said homogeneous and isotropic mixture on a substrate or filling said homogeneous and isotropic mixture into a space between two substrates, wherein at least one of the two substrates is actinic light transmitting, wherein step (b) is performed within the same temperature range as defined in step (a), (c) irradiating at least one surface of the optically transparent film of step b) with an inhomogeneous light field of actinic light such that areas of the film are irradiated while others are not or substantially not irradiated, said step of irradiating being performed within the temperature range as defined in step (a) and having an intensity sufficiently low that the first areas being solely, substantially or mainly composed of photocured polymer are formed, while the liquid crystal or liquid crystal mixture components completely, substantially or mainly escape into the second areas which are not or substantially not irradiated, whereby said rigid or flexible film is formed, and (d) removing one or both of the two substrates depending on whether said rigid or flexible film is to be prepared alone or said rigid or flexible film is to be prepared on one of the two substrates. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 40)
- or for the production of an optical element comprising said film disposed on a flat, light transmitting substrate or between two flat substrates, wherein at least one of the two substrates is light transmitting;
Specification