CN-117389076-B - Preparation method of liquid crystal elastomer microstructure based on photopolymerization phase separation

CN117389076BCN 117389076 BCN117389076 BCN 117389076BCN-117389076-B

Abstract

The invention relates to a preparation method of a liquid crystal elastomer microstructure based on photopolymerized phase separation, which comprises the steps of S1, filling a mixture of photopolymer monomers and liquid crystal between a first substrate and a second substrate of the first liquid crystal box, wherein the first substrate is a substrate without an orientation layer, the second substrate is coated with the orientation layer, S2, covering a gray mask on the first surface of the first substrate of the first liquid crystal box, enabling the first surface of the first substrate to be a surface far away from the mixture, S3, carrying out ultraviolet exposure on the gray mask until the photopolymer monomers and the liquid crystal are separated to obtain a composite structure, and S4, processing the composite structure according to a preset preparation strategy of the liquid crystal elastomer microstructure based on a pre-configured liquid crystal elastomer prepolymer to obtain the liquid crystal elastomer microstructure. The thickness of the liquid crystal elastomer microstructure film prepared by the method ranges from a few micrometers to tens of micrometers, the orientation is good, the manufacturing process is simple, the cost is low, and the precision is high.

Inventors

LIU YANJUN
CHENG MING
CAI WENFENG

Assignees

南方科技大学

Dates

Publication Date: 20260508
Application Date: 20230829

Claims (9)

1. The preparation method of the liquid crystal elastomer microstructure based on photopolymerization phase separation is characterized by comprising the following steps of: s1, for a first liquid crystal box with a specified thickness, a mixture of photopolymer monomers and liquid crystal is filled between a first substrate and a second substrate of the first liquid crystal box, the first substrate is an upper substrate without an orientation layer, the second substrate is a lower substrate, and the first surface of the second substrate facing the mixture is coated with the orientation layer; S2, covering a gray mask on a first surface of a first substrate of the first liquid crystal box, wherein the first surface of the first substrate is a surface far away from the mixture; S3, carrying out ultraviolet exposure on the gray mask until the photopolymer monomer and the liquid crystal are completely separated, wherein the photopolymer monomer is gathered on the second surface of the first substrate to form a polymer microstructure film, and the liquid crystal is gathered on the first surface of the second substrate to obtain a composite structure; s4, processing the composite structure based on a pre-configured liquid crystal elastomer prepolymer according to a preparation strategy of a preset liquid crystal elastomer microstructure to obtain the liquid crystal elastomer microstructure; The step S4 comprises the following steps: S41, preprocessing a first substrate with a polymer microstructure film gathered in a composite structure to obtain a third substrate, wherein the polymer microstructure film gathered on a second surface of the third substrate is provided with an orientation layer; s42, forming a second liquid crystal box by using a third substrate and a fourth substrate, wherein a liquid crystal elastomer prepolymer is filled between the third substrate and the fourth substrate of the second liquid crystal box, an orientation layer is arranged on the first surface of the fourth substrate facing the liquid crystal elastomer prepolymer, and the second surface of the third substrate faces the liquid crystal elastomer prepolymer; S43, performing ultraviolet exposure on the first surface of the third substrate of the second liquid crystal box until the liquid crystal elastomer prepolymer is polymerized and cured; S44, stripping the polymerized and cured liquid crystal elastomer prepolymer from the second liquid crystal box to obtain the liquid crystal elastomer microstructure.
2. The method of preparing a microstructure of a liquid crystal elastomer as claimed in claim 1, wherein S41 comprises: s41-1, cleaning, drying and carrying out ultraviolet ozone hydrophilic treatment on a first substrate in the composite structure; S41-2, spin-coating a polyvinyl alcohol aqueous solution on the first substrate subjected to the hydrophilic treatment and drying; S41-3, carrying out friction orientation on the dried first substrate, so that an orientation layer is formed on the surface of the polymer microstructure film on the first substrate, and a third substrate is obtained.
3. The method for preparing a microstructure of a liquid crystal elastomer as claimed in claim 1, wherein the step S4 comprises: s41', cleaning the composite structure until liquid crystal in the composite structure is completely washed out; s42', filling the cleaned composite structure by using a pre-configured liquid crystal elastomer prepolymer to obtain a third liquid crystal box, wherein the third liquid crystal box comprises a first substrate, a second substrate and the liquid crystal elastomer prepolymer filled between the first substrate and the second substrate; s43', performing ultraviolet exposure on the first surface of the first substrate of the third liquid crystal box until the liquid crystal elastomer prepolymer is polymerized and cured; s44', stripping the polymerized and cured liquid crystal elastomer prepolymer from the second liquid crystal box to obtain the liquid crystal elastomer microstructure.
4. The method for preparing a microstructure of a liquid crystal elastomer according to claim 1, wherein, The pre-configured liquid crystal elastomer prepolymer comprises a liquid crystal polymer monomer, a cross-linking agent and a photoinitiator; Wherein the mass fraction of the liquid crystal polymer monomer is 60mol% to 80mol%; the mass fraction of the crosslinking agent is 15mol% to 30mol%; The mass fraction of the photoinitiator is 1 mol% to 5mol%.
5. The method for preparing a microstructure of a liquid crystal elastomer according to claim 1, wherein, And when the gray mask in the step S3 is subjected to ultraviolet exposure, the temperature of the mixture of the photopolymer monomer and the liquid crystal is kept stable at 100+/-10 ℃.
6. The method of manufacturing a microstructure of a liquid crystal elastomer as claimed in claim 5, wherein the ultraviolet light intensity of the ultraviolet exposure of the gray mask is 0.4-0.8mW/cm 2 , and the exposure time is 20-40min.
7. The preparation method of the liquid crystal elastomer microstructure based on photopolymerization phase separation is characterized by comprising the following steps of: A1, filling a mixture of a liquid crystal elastomer prepolymer and liquid crystal between a fifth substrate and a sixth substrate of the fourth liquid crystal box aiming at a fourth liquid crystal box with a specified thickness, wherein an alignment layer is coated on a second surface of the fifth substrate and a first surface of the sixth substrate; A2, covering a gray mask on the first surface of a fifth substrate of the fourth liquid crystal box, wherein the first surface of the fifth substrate is a surface far away from the mixture; a3, carrying out ultraviolet exposure on the gray mask until the liquid crystal elastomer prepolymer and the liquid crystal are completely separated, wherein the liquid crystal elastomer prepolymer is gathered on the second surface of the fifth substrate to form a liquid crystal elastomer microstructure, and the liquid crystal is gathered on the first surface of the sixth substrate; and A4, stripping the liquid crystal elastomer microstructure from the fourth liquid crystal box to obtain the liquid crystal elastomer microstructure.
8. The method for preparing a microstructure of a liquid crystal elastomer according to claim 7, wherein, In the mixture of the liquid crystal elastomer prepolymer and the liquid crystal, the mass ratio of the liquid crystal elastomer prepolymer to the liquid crystal is 1:1.
9. A liquid crystal elastomer microstructure formed by the method of any one of claims 1 to 8.

Description

Preparation method of liquid crystal elastomer microstructure based on photopolymerization phase separation Technical Field The invention relates to the technical field of preparation of liquid crystal elastomer microstructures, in particular to a preparation method of a liquid crystal elastomer microstructure based on photopolymerization phase separation. Background In recent years, with the development of technology, as an intelligent material with liquid crystal ordering and elastomer elasticity, the liquid crystal elastomer can respond to various external stimuli such as heat, light, electricity, magnetism, humidity and the like, can be miniaturized, can remotely realize contactless light control and deformation, can be randomly arranged based on orientation, and has wide application prospect. At present, the preparation of common liquid crystal elastomer microstructures combines soft lithography with magnetic field orientation, 4D printing and self-assembly. The method comprises the steps of preparing a silicon microstructure array based on photoetching and etching technology by combining soft photoetching with magnetic field orientation, pouring prepolymer of a liquid crystal elastomer into a PDMS mould after mould inversion, simultaneously carrying out orientation by using a magnetic field, carrying out photopolymerization at nematic phase temperature, and finally stripping the PDMS to obtain the liquid crystal elastomer microstructure. Because the method needs photoetching and etching, and also needs a larger magnetic field for orientation, the device is huge, and the defects of complex steps, higher cost, single orientation form of a finished product and incapability of obtaining complex orientation exist. The 4D printing is to use shearing force during extrusion of the liquid crystal elastomer to orient or to use laser and ultraviolet light to print point by point and layer by layer, so that a single liquid crystal elastomer micro-actuator is prepared, and a surface micro-structure array is rarely prepared. The defects of slow printing speed, incapability of realizing mass production and processing and preparation of large-area samples, huge device, expensive equipment, long time consumption and limited application exist. Self-assembly comprises a self-assembly structure formed on the surface of a liquid crystal elastomer material and soft embossing by other self-assembly materials, and has the defect that the shape of a microstructure is single, the self-assembly structure is limited by the self-assembly materials and the structure, and arbitrary design cannot be carried out. Disclosure of Invention First, the technical problem to be solved In view of the above-mentioned shortcomings and disadvantages of the prior art, the present invention provides a preparation method of a liquid crystal elastomer microstructure based on photopolymerization phase separation, which solves the technical problems of high preparation cost, low precision, difficult mass production and difficult large-area preparation of the liquid crystal elastomer microstructure in the prior art. (II) technical scheme In order to achieve the above object, in a first aspect, the present invention provides a method for preparing a microstructure of a liquid crystal elastomer based on photopolymerization phase separation, comprising: s1, for a first liquid crystal box with a specified thickness, a mixture of photopolymer monomers and liquid crystal is filled between a first substrate and a second substrate of the first liquid crystal box, the first substrate is an upper substrate without an orientation layer, the second substrate is a lower substrate, and the first surface of the second substrate facing the mixture is coated with the orientation layer; S2, covering a gray mask on a first surface of a first substrate of the first liquid crystal box, wherein the first surface of the first substrate is a surface far away from the mixture; S3, carrying out ultraviolet exposure on the gray mask until the photopolymer monomer and the liquid crystal are completely separated, wherein the photopolymer monomer is gathered on the second surface of the first substrate to form a polymer microstructure film, and the liquid crystal is gathered on the first surface of the second substrate to obtain a composite structure; S4, processing the composite structure based on a pre-configured liquid crystal elastomer prepolymer according to a preparation strategy of a preset liquid crystal elastomer microstructure to obtain the liquid crystal elastomer microstructure. Optionally, the S4 includes: S41, preprocessing a first substrate with a polymer microstructure film gathered in a composite structure to obtain a third substrate, wherein the polymer microstructure film gathered on a second surface of the third substrate is provided with an orientation layer; s42, forming a second liquid crystal box by using a third substrate and a fourth substrate, wherein a