Photochromic Ionic Solvent for Fast Decolorization
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Solution Overview
Problem
Photochromic devices, such as lenses, face a slow deactivation issue when transitioning from bright to dark environments, as they typically require several minutes to return to a colorless state, causing inconvenience to users.
Innovation Solution
A photochromic composition comprising at least one colorless photochromic dye, specifically naphtho[2,1-b]pyrans or naphtho[1,2-b]pyrans, dissolved in an ionic solvent with a melting point below 100°C, which includes a mixture of ionic liquids and organic solvents, allowing for faster decolorization and improved optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If photochromic dyes are used in conventional solid or liquid matrices, then the lenses provide photochromic functionality, but the deactivation time is slow (several minutes to tens of minutes)
Solution Approach 1:
The patent changes the physical and chemical parameters of the matrix by using ionic liquids with specific viscosity ranges (0.1-100 cP) and molecular structures. This parameter optimization enables faster molecular mobility and significantly reduces deactivation time from minutes to seconds while maintaining photochromic functionality.
Solution Approach 2:
The patent employs composite material systems combining photochromic dyes with ionic liquid matrices. This composite approach integrates the photochromic properties of organic dyes with the unique solvation and mobility characteristics of ionic liquids, achieving both rapid activation and fast deactivation.
2Speed
If photochromic dyes are dissolved in liquid matrices for faster deactivation, then the response speed improves, but the manufacturing complexity and material selection constraints increase
Solution Approach 1:
The patent establishes specific parameter ranges for ionic liquids including viscosity (0.1-100 cP), melting point (below room temperature), and molecular structure characteristics. These parameter specifications enable systematic material selection and simplify the manufacturing process by providing clear design criteria.
Solution Approach 2:
The ionic liquid acts as an intermediary medium between the photochromic dye and the final lens product. This intermediary enables the dye to achieve rapid response while the ionic liquid's stable properties simplify handling, processing, and manufacturing procedures.
3Reliability
If conventional organic solvents are used, then the photochromic dye dissolves well, but the vapor pressure is high and thermal stability is insufficient
Solution Approach 1:
The patent changes the fundamental parameters of the solvent system by transitioning from conventional organic solvents to ionic liquids. This results in dramatically reduced vapor pressure (negligible evaporation), enhanced thermal stability (stable up to 100°C and beyond), and improved photochemical stability while maintaining excellent dye solubility.
Solution Approach 2:
The ionic liquid matrix forms a stable composite system with photochromic dyes, combining the advantages of liquid-state mobility with enhanced thermal and chemical stability. This composite structure prevents solvent evaporation and degradation while maintaining optical clarity and dye solubility.
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 use of ionic solvents significantly reduces the decolorization time and enhances the difference in transmission between activated and inactivated states, enabling faster response times and improved performance in optical devices.
Implementation Method 1
Photochromism is a well-known physical phenomenon observed in certain classes of compounds. A detailed discussion of this phenomenon can be found in 'Photochromism: Molecules and Systems', Studies in Organic Chemistry 40, edited by H. Durr and H. Bouas-Laurent, Elsevier, 1990.
Data Source
AI summary
A photochromic composition that is liquid at 20 °C and includes (a) at least one photochromic dye and (b) an ionic solvent selected from (b)(i) room-temperature ionic liquids (RTIL), (b)(ii) ionic liquid mixtures that are liquid at room temperature, and (b)(iii) room-temperature liquid mixtures of at least one ionic liquid and at least one organic solvent that is miscible therewith. The use of said photochromic composition in optical devices such as ophthalmic lenses is also described.