Liquid Crystal Film with Variable Polymer Networks for Reversible Encryption
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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.
Innovation Solution
A liquid crystal film with a composite functional layer comprising a honeycomb-shaped polymer matrix and varying polymer network density regions, allowing reversible information patterns through electric or thermal stimuli, achieved by precise control of polymerization rates and molecular orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymer-dispersed liquid crystals (PDLCs) with high polymer matrix content are used to achieve high peel strength and large-area flexible films, then film mechanical strength and area are improved, but the porous polymer matrix fails to provide induction or stabilization for liquid crystal molecule orientation, resulting in single light-modulation characteristic and inability to achieve diverse patterns
Solution Approach 1:
The patent introduces polymer networks with spatially varying distribution densities within the liquid crystal film. Different regions contain different densities of polymer networks, creating local variations in liquid crystal molecule orientation control. This enables diverse patterning regions (transparent, scattering, different orientations) within a single film that maintains high peel strength through the polymer matrix.
2Ease of operation
If small-molecule liquid crystals are used for information patterning, then reversible patterning function is achieved, but the liquid state makes it difficult to prepare large-area flexible films
Solution Approach 1:
The patent creates a composite material system combining small-molecule liquid crystals with a polymer matrix and polymer networks. The polymer matrix provides mechanical strength for large-area flexible films, while the liquid crystal components maintain reversible patterning functionality. The polymer networks embedded within provide additional orientation control without sacrificing the reversible switching capability.
3Ease of manufacture
If polymeric liquid crystals are used to improve film preparation, then large-area flexible films can be fabricated, but high viscosity poses challenges in achieving uniform large-area orientation and pattern switching
Solution Approach 1:
The patent employs a porous polymer matrix structure containing embedded polymer networks. This porous architecture provides induction sites for liquid crystal molecule orientation while maintaining low enough viscosity for uniform large-area processing. The polymer networks within the pores act as nucleation points that guide orientation without requiring extremely high viscosity.
4Adaptability or versatility
If polymer-stabilized liquid crystal (PSLC) films with low polymer network content are used, then various patterns can be implemented, but peel strength between substrates is low, making it difficult to prepare large-area flexible films
Solution Approach 1:
The patent changes the polymer network content parameter from the typical low concentration in PSLC films to a higher concentration with varying distribution densities. This parameter change simultaneously achieves both high peel strength for large-area flexible films and diverse patterning capability through the spatially varying network densities that create different local orientation conditions.
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 and visual effects, facilitating large-area processing and dynamic information encryption and display functions.
Implementation Method 1
liquid crystals exhibit stimulus-responsiveness to external fields such as an electric field, a magnetic field, heat, pressure, and humidity
Implementation Method 2
In electrochromic liquid crystal materials, small-molecule liquid crystals, polymer-dispersed liquid crystals, and polymer-stabilized liquid crystals all serve as excellent electrochromic materials
Implementation Method 3
In thermochromic liquid crystal materials, temperature-sensitive color-changing devices, such as film thermometers, have been widely applied
Implementation Method 4
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
Implementation Method 5
PDLCs, due to the high polymer matrix content, exhibit high peel strength between the two substrates, allowing for the preparation of large-area flexible films
Implementation Method 6
a series of photochromic materials have been developed by incorporating azobenzene, molecular motors, molecular switches, etc. into the small-molecule and polymeric liquid crystals
Data Source
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Figure 2b~3
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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.