Photoreactive Polymer with Multi-Cyclic Main Chain for Liquid Crystal Alignment
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Solution Overview
Problem
Existing photoreactive polymers for liquid crystal displays suffer from poor thermal stability and slow photoreaction rates, leading to reduced alignment quality and surface strength, which limits their application in large-scale liquid crystal displays.
Innovation Solution
A photoreactive polymer with a multi-cyclic compound in the main chain, featuring a photoactive functional group, is developed, allowing for rapid photoreaction and improved thermal stability through the use of a catalyst mixture with Group 4, 6, and 8 transition metals, and metallocene catalysts for polymerization, enhancing the polymer's mobility and surface strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If polycinnamate-based polymer (PVCN or PVMC) is used as photoreactive polymer, then optical alignment property is excellent, but thermal stability is poor due to glass transition temperature of 100°C or less
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by introducing multi-cyclic compounds (norbornene, cyclohexene, indene structures) into the main chain. This structural modification increases the glass transition temperature from 100°C or less to above 100°C, thereby improving thermal stability while maintaining photoreactive properties through incorporated photoactive groups
Solution Approach 2:
The patent creates a composite polymer structure by combining multi-cyclic compound backbones with photoactive functional groups (cinnamate, coumarin, oxa dihydrocoumarin groups). This composite approach integrates the thermal stability of cyclic structures with the photoreactive capabilities of photoactive groups, achieving both high thermal stability and rapid photoreaction
2Productivity
If conventional photoreactive polymer is used, then photoreaction can occur, but photoreaction rate is slow, reducing alignment quality and productivity
Solution Approach 1:
The patent modifies molecular mobility parameters by incorporating multi-cyclic structures that increase free volume and chain flexibility. This enhancement of molecular mobility accelerates the photoreaction rate, allowing rapid alignment while maintaining high alignment quality through proper photoactive group orientation
Solution Approach 2:
The patent replaces conventional slow photoreaction mechanisms with an enhanced photoreaction system using multi-cyclic compounds. The cyclic structures facilitate faster molecular reorganization under UV irradiation, substituting the slow alignment process with a rapid photoreaction-driven alignment mechanism
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 resulting polymer exhibits excellent thermal stability and rapid photoreaction, improving the alignment quality and surface strength of liquid crystal films, making it suitable for large-scale liquid crystal displays.
Implementation Method 1
a metallocene catalyst and a cocatalyst are used to conduct ring-opening polymerization
Implementation Method 2
ring-opening polymerization of a cyclic olefin monomer having a photoactive group
Implementation Method 3
a liquid crystal alignment film is used... perform a photopolymerization by using the radiation of light so that the alignment of polymer is induced to align liquid crystals
Implementation Method 4
The optical alignment is a mechanism in which a photoreaction of a photosensitive group that is connected to the polymer occurs due to linearly polarized ultraviolet rays
Data Source
AI summary
The present invention relates to a photoreactive polymer that comprises a multi-cyclic compound in a main chain, and a polymerization method thereof. Since the photoreactive polymer according to the present invention comprises a multi-cyclic compound having a high glass transition temperature as a main chain, the thermal stability is excellent, and since the mobility of the main chain is relatively high as compared to that of an additional polymer, a photoreactive group can be freely moved in the main chain of the polymer. Accordingly, it is possible to overcome a slow photoreactive rate that is considered a disadvantage of a polymer material used to prepare an alignment film for known liquid crystal display devices.