Segmented Polymer Photochromic Composition for Hardness and Fast Kinetics
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Solution Overview
Problem
Existing curable photochromic compositions face a challenge in achieving a balance between hardness and photochromic performance, with soft matrices providing faster kinetics but reduced hardness, and hard matrices offering increased hardness at the expense of slower kinetics.
Innovation Solution
A curable photochromic composition comprising a photochromic compound, a trialkoxysilane functional material with at least two trialkoxysilane groups, and a segmented polymer with specific segments such as (meth)acrylic, fluoroethylene vinyl ether, polycarbonate, polyester, or polyurethane segments, to enhance hardness without compromising photochromic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a soft matrix is used in the cured photochromic film, then the kinetics of reversible transformation are faster, but the hardness is reduced
Solution Approach 1:
The polymer matrix is segmented into multiple functional segments: first segments comprising (meth)acrylic or fluoroethylene vinyl ether polymer units providing softness and fast kinetics, and second segments comprising polycarbonate, polyester, polyether, or polyurethane segments providing hardness. This segmentation allows each segment to fulfill its specific function independently, resolving the contradiction between softness for kinetics and hardness for durability.
Solution Approach 2:
The invention creates a composite polymer matrix combining different polymer types with complementary properties. The (meth)acrylic and fluoroethylene vinyl ether segments form a soft, flexible matrix that enables fast photochromic kinetics, while the polycarbonate, polyester, polyether, or polyurethane segments form a hard, durable matrix that provides mechanical strength. The synergistic combination of these composite segments achieves both fast kinetics and high hardness simultaneously.
2Strength
If a hard matrix is used in the cured photochromic film, then the hardness is increased, but the kinetics of reversible transformation are slower
Solution Approach 1:
The polymer matrix is divided into distinct functional segments: first segments with (meth)acrylic or fluoroethylene vinyl ether units that provide softness and fast kinetics, and second segments with polycarbonate, polyester, polyether, or polyurethane units that provide hardness. This segmentation ensures that the hard segments enhance mechanical properties while the soft segments maintain fast photochromic response kinetics.
Solution Approach 2:
The composite polymer structure combines soft (meth)acrylic and fluoroethylene vinyl ether segments with hard polycarbonate, polyester, polyether, or polyurethane segments. This composite architecture allows the hard segments to provide mechanical strength and durability while the soft segments create pathways for rapid molecular motion and fast photochromic kinetics, eliminating the trade-off between hardness and kinetics.
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 composition achieves improved hardness in cured photochromic layers while maintaining fast kinetics and photochromic performance, addressing the trade-off between hardness and functionality in existing compositions.
Implementation Method 1
a trialkoxysilane functional material having at least two trialkoxysilane groups
Implementation Method 2
In response to certain wavelengths of electromagnetic radiation (or 'actinic radiation'), photochromic compounds, such as indeno-fused naphthopyrans, typically undergo a transformation from one form or state to another form, with each form having a characteristic or distinguishable absorption spectrum associated therewith
Data Source
AI summary
The present invention relates to, a curable photochromic composition that includes a photochromic compound, a trialkoxysilane functional material having at least two trialkoxysilane groups, and a segmented polymer that includes at least one first segment, and at least one second segment. Each first segment, of the segmented polymer, independently includes a (meth)acrylic polymer segment, and/or a fluoroethylene vinyl ether polymer segment. Each second segment, of the segmented polymer, independently includes, a polycarbonate segment, a polyester segment, a polyether segment, a polyurethane segment, or combinations thereof. The present invention also relates to an article that includes: a substrate; and a photochromic layer over at least one surface of the substrate, where the photochromic layer is formed from the curable photochromic composition of the present invention.