Aligned liquid crystal thin films and glasses
View Patent ↗The present disclosure includes a method that allows one to obtain high quality alignment of nematic or smectic liquid crystal (LC) polymer glasses in thin films. The present disclosure also includes thin films of aligned smectic or nematic LC main-chain polymer glasses, including aligned chiral smectic C* ferroelectric LC main-chain polymer glasses. The disclosure also includes electro-optical devices, including electro-optical devices comprising aligned chiral smectic C* ferroelectric LC main-chain polymer glasses.
1. A method for aligning smectic liquid crystal glasses in thin films comprising the steps of:
(a) heating a glassy liquid crystal (LC) main-chain polymer fiber into a smectic LC phase;
(b) compressing said main-chain polymer fiber in the smectic phase between opposed substrates wherein an aligned thin film of smectic LC main-chain polymer is formed between said opposed substrates; and
(c) cooling said thin film of smectic LC main-chain polymer into the glassy phase.
2. The method of claim 1 wherein the thin film in the glassy phase is in the frozen smectic phase.
3. The method of claim 2 wherein said smectic phase is selected from the group consisting of a smectic C* phase, a smectic A* phase, a smectic C phase, a polar smectic C phase, and a smectic A phase.
4. The method of claim 3 wherein said smectic phase is a smectic C* phase.
5. The method of claim 4 wherein the smectic C phase is a smectic C* ferroelectric LC phase.
6. The method of claim 1 wherein said main-chain polymer fiber has a diameter of from about 1 μm to about 100 μm.
7. The method of claim 1 wherein at least one of said substrates is comprised of glass.
8. The method of claim 1 wherein at least one of said substrates is comprised of a semi-conductor.
9. The method of claim 1 wherein said opposed substrates are separated by spacers.
10. The method of claim 1 wherein one or both of the heating and cooling steps is performed using a Peltier effect element.
11. The method of claim 1 wherein said main-chain polymer fiber is compressed using a weight placed on at least one of said opposed substrates.
12. The method of claim 1 wherein said main-chain polymer fiber is compressed by action of a piston on at least one of said opposed substrates.
13. The method of claim 1 wherein said LC main-chain polymer fiber in the glassy phase is prepared by pulling a fiber from an isotropic melt of the LC main-chain polymer.
14. The method of claim 1 wherein said LC main-chain polymer fiber in the glassy phase is prepared by extruding a fiber from an isotropic melt of the LC main-chain polymer.
15. The method of claim 1 wherein said main-chain polymer is
16. The method of claim 1 wherein the transition from the smectic LC phase to the glassy phase occurs at above room temperature.