Polyester-Linked Photochromic Polymers for Rapid Kinetics
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Solution Overview
Problem
Current photochromic polymers face limitations in controlling the rate of coloration and fading, particularly in applications like spectacles, where rapid kinetics are desired but compromised by the need for abrasion resistance and hardness, and siloxane-based polymers are prone to phase separation and acid degradation.
Innovation Solution
A photochromic polymer comprising at least two photochromic moieties linked by a linear or branched polyester chain, which provides improved photochromic performance, compatibility, and stability, avoiding the issues of phase separation and acid degradation, while allowing for controlled coloration and fading rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If photochromics are used in soft materials to enhance rate of coloration and fade, then photochromic efficiency is improved, but abrasion resistance and hardness deteriorate
Solution Approach 1:
The invention changes the chemical structure of the photochromic compound by introducing a carbocyclic ring system with specific substituents (aromatic groups, heteroatoms). This structural modification allows the photochromic to maintain rapid coloration and fading kinetics while being compatible with harder, more abrasion-resistant polymer matrices, thus resolving the contradiction between speed and strength
Solution Approach 2:
The patent creates a composite system where the modified photochromic compound is integrated into a polymeric lens material. The photochromic acts as a functional additive within the polymer matrix, combining the optical properties of the photochromic compound with the mechanical properties of the polymer, achieving both rapid kinetics and abrasion resistance
2Speed
If polydialkylsiloxane oligomers are used to improve rate of coloration and fade, then photochromic performance is enhanced, but phase separation occurs at increased loading
Solution Approach 1:
The invention modifies the photochromic structure to include carbocyclic rings with specific substituent patterns that enhance compatibility with polymer matrices. This structural parameter change allows achieving fast kinetics without the phase separation problem associated with siloxane-based photochromics at higher concentrations
Solution Approach 2:
The patent employs a photochromic compound design that does not rely on labile siloxane oligomer structures. The more stable carbocyclic-based photochromic provides durable performance without the phase separation issues, effectively replacing the short-lived siloxane approach
3Speed
If siloxane photochromic polymers are used to achieve rapid fading, then photochromic efficiency is improved, but susceptibility to acid degradation increases
Solution Approach 1:
The patent changes the chemical composition of the photochromic compound by using carbocyclic ring systems with aromatic substituents instead of siloxane-based structures. This parameter change maintains rapid fade rates while eliminating the acid degradation susceptibility inherent in siloxane polymers, thus improving reliability
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 polyester-linked photochromic polymer achieves rapid and efficient coloration and fading, enhancing the versatility and performance of photochromic materials in applications such as spectacles by balancing kinetics and mechanical properties.
Implementation Method 1
Photochromism is a property which has been used in the manufacture of light transmissible articles for many years. A compound is said to be photochromic if it changes colour when irradiated and reverts to its original colour when irradiation ceases.
Data Source
AI summary
A photochromic polymer comprising at least two photochromic moieties linked by a straight or branched chain polymer selected from the group consisting of a homo- polyester, a co-polyester, and a co-polyester-polyether.