Polymerisable LC Material for Thin Films With Stable Optical Dispersion
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Solution Overview
Problem
Existing polymerisable liquid crystal materials exhibit poor thermal durability, yellowing, and require thick films due to low birefringence, making them unsuitable for mass production and thin film applications.
Innovation Solution
A polymerisable LC material with a specific molecular structure (RT1-(AT1-ZT1)m1-GT1-(ZT2-AT2)m2-RT2) that enhances birefringence, thermal stability, and transparency, allowing for thinner films with improved adhesion and uniform alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If highly conjugated substituents are used in the orthogonal position to achieve flat or negative optical dispersion, then the optical properties are improved, but the material absorbs UV dose during curing resulting in poor degree of cure and poor thermal durability
Solution Approach 1:
The patent modifies the molecular structure by placing highly conjugated substituents in the orthogonal position (perpendicular to the long axis) of the liquid crystal molecule. This structural parameter change enables flat or negative optical dispersion while the specific molecular architecture controls UV absorption characteristics during curing, resolving the contradiction between optical performance and thermal durability
Solution Approach 2:
The invention uses a composite molecular structure combining the highly conjugated substituent group with specific liquid crystal core structures (cyclic carbonate, cyclosiloxane). This composite approach allows the material to achieve both the desired optical dispersion properties and improved thermal stability through synergistic molecular design
2Illumination intensity
If highly conjugated reactive mesogens are used to achieve high birefringence, then the optical properties are improved, but the thermal durability of cured films is reduced and yellowing occurs
Solution Approach 1:
The patent applies local quality by positioning the highly conjugated substituent group specifically in the orthogonal position rather than along the long axis. This localized structural modification enables high birefringence while the specific spatial arrangement prevents excessive UV absorption and thermal degradation, avoiding yellowing and maintaining thermal durability
Solution Approach 2:
The invention changes the molecular orientation parameter by placing conjugated groups perpendicular to the long axis rather than parallel. This parameter change achieves high birefringence through optimized electron cloud anisotropy while preventing the thermal degradation and yellowing associated with conventional high-conjugation structures
3Illumination intensity
If conventional LC materials with low birefringence are used, then the material formulation is simpler, but the film thickness must be increased to achieve the required retardation
Solution Approach 1:
The patent achieves high birefringence (Δn ≥ 0.15) by incorporating highly conjugated substituent groups in the orthogonal position, which significantly enhances the optical anisotropy of the liquid crystal molecules. This parameter change allows thin films (≤30 μm) to achieve the required retardation without increasing thickness
4Illumination intensity
If bulky negative dispersion compounds are used to achieve negative optical dispersion, then the optical properties are improved, but the compounds are hard to align and give formulations with a narrow process window for annealing temperature
Solution Approach 1:
The patent modifies the molecular shape parameter by using linear or slightly extended structures with highly conjugated substituents in the orthogonal position, rather than bulky three-dimensional structures. This parameter change improves alignability and widens the annealing process window while maintaining negative optical dispersion properties
Solution Approach 2:
Instead of using bulky structures to achieve negative dispersion, the invention inverts the approach by using linear structures with orthogonally positioned conjugated groups. This inverted structural strategy achieves the same optical effect while dramatically improving manufacturability and alignment characteristics
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 new material enables the production of thinner, more durable polymer films with favorable optical properties, suitable for mass production and various optical, electronic, and electro-optical devices.
Implementation Method 1
polymerisable liquid crystal materials are known in prior art for the preparation of anisotropic polymer films
Implementation Method 2
fixing the orientation of the liquid crystal molecules by polymerizing the polymerizable liquid crystal material
Implementation Method 3
optical films based on polymerisable liquid crystal materials typically exhibit a wavelength dependent retardation
Implementation Method 4
The latter materials absorb part of the UV dose when curing optical films which results in poor degree of cure and poor thermal durability of cured films
Data Source
AI summary
A polymerisable liquid crystal (LC) compound, a corresponding polymerizable LC material, a polymer film with flat, negative, or positive optical dispersion obtainable from such a material, and the use of the polymerisable LC, polymerisable LC material and/or polymer film in optical, electro optical, electronic, semiconducting, or luminescent components or devices.