Liquid Crystal Film With Switchable Encrypted Information Patterns
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Solution Overview
Problem
Existing liquid crystal-based information-patterning controllable materials face challenges in film preparation, pattern switching, and inability to achieve diverse patterning, particularly in large-area flexible films, due to issues such as high viscosity, low peel strength, and single light-modulation characteristics.
Innovation Solution
A liquid crystal film with a composite functional layer comprising a honeycomb-shaped polymer matrix and varying polymer network density, allowing reversible pattern changes under electric fields or temperature variations, using components like flexible polymerizable monomers, liquid crystals, initiators, and spacer particles, and a three-step curing process to achieve customized patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If small-molecule liquid crystals are used for information patterning, then reversible pattern switching is achieved, but large-area flexible film preparation becomes difficult due to liquid state
Solution Approach 1:
The patent uses polymer-stabilized liquid crystal (PSLC) composite materials, where liquid crystal molecules are dispersed in a polymer matrix. This composite structure combines the liquid crystal's reversible pattern switching capability with the polymer's solid-state mechanical properties, enabling both pattern switching operation and large-area flexible film preparation.
Solution Approach 2:
The patent prepares large-area flexible films by embedding liquid crystal-polymer composite materials between flexible substrate layers, creating a thin film structure that maintains flexibility while enabling reversible pattern switching through external field application.
2Ease of manufacture
If polymeric liquid crystals are used for information patterning, then film preparation is improved, but uniform large-area orientation becomes difficult due to high viscosity
Solution Approach 1:
The patent introduces spacers with different heights (first spacers and second spacers) to create local variations in gap thickness. This local quality differentiation enables controlled liquid crystal orientation in different regions, achieving uniform large-area orientation despite the high viscosity of polymeric liquid crystals.
Solution Approach 2:
The patent uses spacer particles as intermediary elements between the substrate and liquid crystal layer. These spacers mediate the orientation of liquid crystal molecules by providing physical constraints and anchoring points, enabling uniform orientation across large areas while working with viscous polymeric liquid crystals.
3Adaptability or versatility
If polymer-stabilized liquid crystal films are used, then pattern diversity is achieved, but peel strength between substrates is low due to low polymer network content
Solution Approach 1:
The patent changes the polymer network content parameter to be within a specific range (5-20 wt%) to optimize both pattern diversity and peel strength. By precisely controlling this parameter, the patent achieves sufficient mechanical strength while maintaining the liquid crystal's ability to form diverse patterns in response to external fields.
Solution Approach 2:
The patent creates a composite structure with optimized polymer-liquid crystal ratio, where the polymer matrix provides mechanical strength and adhesion between substrates, while the liquid crystal phase maintains its ability to form diverse patterns. This composite approach balances strength and versatility requirements.
4Ease of manufacture
If polymer-dispersed liquid crystals are used, then large-area flexible films with high peel strength are achieved, but diverse patterning is lost due to porous polymer matrix structure
Solution Approach 1:
The patent creates regions with different polymer network densities (first regions and second regions) within the liquid crystal film. The first regions have higher polymer content providing structural stability, while the second regions have lower polymer content allowing liquid crystal reorientation and pattern formation, thus achieving both film integrity and diverse patterning capability.
Solution Approach 2:
The patent segments the liquid crystal film into functional regions with different properties. By dividing the film into regions with varying polymer network densities, the patent enables different functional zones: some regions provide mechanical support while others enable pattern switching, achieving both large-area film stability and diverse patterning.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The film enables rich customization of information patterns, precise pattern construction, and large-area processing, offering dynamic information encryption and display functions through reversible changes in light transmittance and scattering.
Implementation Method 1
utilizing the smectic or crystalline-cholesteric phase transitions of small-molecule and polymeric liquid crystal materials
Implementation Method 2
electrochromic liquid crystal materials... can achieve reversible information patterning functions under the action of the external fields
Implementation Method 3
thermochromic liquid crystal materials... temperature-sensitive color-changing devices... can achieve reversible information patterning functions under the action of the external fields
Implementation Method 4
0.5 wt % to 15 wt % of rod-shaped photopolymerizable monomers... undergo free radical polymerization or cationic polymerization under ultraviolet light irradiation
Data Source
AI summary
The present disclosure relates to the technical field of functional liquid crystal materials, and discloses a liquid crystal film with an intelligent information encryption function and a preparation method and use thereof. The liquid crystal film includes two layers of parallel transparent substrates and a composite functional layer between the transparent substrates; and the composite functional layer includes a honeycomb-shaped polymer matrix and liquid crystals filled in pores of the polymer matrix, where the liquid crystals comprise a polymer network; and the distribution density of the polymer network varies in different regions of the liquid crystal film, thereby allowing the liquid crystal film to exhibit a reversible changing information pattern that disappears (or appears) upon application of an electric field and appears (or disappears) after removal of the electric field, or a reversible changing information pattern that disappears (or appears) at low temperatures and appears (or disappears) at high temperatures.