Curable Liquid Crystal Compounds for Phase Retarder Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing liquid crystal polymers (LCPs) used in optical and electro-optical devices face challenges such as high melting points, narrow operating ranges, and issues with optical anisotropy, leading to inhomogeneous film formation and reduced alignment properties, which limit their performance in phase retarders and other optical applications.
Innovation Solution
Development of laterally substituted curable liquid crystals with adjustable optical anisotropy and low melting points, allowing for better solubility and miscibility, and reduced formation of tilt domains and disclinations, enabling the creation of thinner, more uniform phase retarder films with improved optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If liquid crystals with high optical anisotropy are used, then the necessary retardation value can be achieved with small quantities of liquid crystal compounds, but high melting points and enhanced tendency to crystallise are observed
Solution Approach 1:
The patent modifies the molecular structure of liquid crystal compounds by introducing specific lateral substituents (groups like -OCH3, -F, -Cl at positions 2, 6, or 7 of the mesogenic core) to change the physical parameters. These structural modifications reduce melting points and crystallization tendency while preserving high optical anisotropy, allowing achievement of necessary retardation values with smaller quantities of material.
2Quantity of substance
If liquid crystals with high optical anisotropy are used, then smaller quantities are needed, but formation of smectic mesophases and reduced solubility in organic solvents is observed
Solution Approach 1:
The patent introduces specific local modifications at particular positions (2, 6, or 7) of the mesogenic core structure. By placing substituents at these specific locations, the molecular packing and intermolecular interactions are locally altered, which improves solubility in organic solvents while maintaining the high optical anisotropy needed for effective retardation with minimal material quantity.
3Quantity of substance
If liquid crystals with high optical anisotropy are used, then smaller quantities are needed, but reduced miscibility with other LCPs is observed
Solution Approach 1:
The patent systematically varies molecular parameters by introducing different lateral substituents (varying atomic size, electronegativity, and steric effects) to adjust the intermolecular compatibility. These parameter changes enable better miscibility with other liquid crystal compounds while preserving the high optical anisotropy required for effective optical performance with minimal material quantity.
4Quantity of substance
If liquid crystals with high optical anisotropy are used, then smaller quantities are needed, but ability to form homogeneous alignment free of tilt domains and disclinations is reduced
Solution Approach 1:
The patent introduces specific local substituents at positions 2, 6, or 7 of the mesogenic core, which locally modify the molecular shape and interaction characteristics. These local modifications reduce the formation of tilt domains and disclinations by optimizing the balance between optical anisotropy and molecular packing, thereby achieving homogeneous alignment while using smaller quantities of material.
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 LCPs achieve higher birefringence with less material, enabling the production of thinner optical films with enhanced alignment properties and improved optical homogeneity, reducing the need for thicker films and increasing efficiency in optical structures.
Implementation Method 1
When light passes through a phase retarder its polarization direction changes because of the birefringence and the thickness of the phase retarder
Implementation Method 2
These compounds are characterised by relatively high melting points... LCP films... a nematic mesophase, a high clearing point
Implementation Method 3
photochemically polymerisable liquid crystal compounds and mixtures... cross-linked to fix the liquid crystalline properties ordered structure
Data Source
AI summary
The invention relates to novel polymerizable liquid crystals of formula (I), to LCP mixtures comprising these compounds and to their uses for optical and electro-optical devices: (I) with the proviso the at least one of the polymerisable groups G1 or G2 is a naphthalenediyl group.