Segmented Polymer Photochromic Composition Hardness Kinetics
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Solution Overview
Problem
Curable photochromic compositions face a challenge in achieving improved hardness without compromising photochromic performance, as softer matrices enhance kinetics but reduce hardness, while harder matrices increase hardness but slow down the reversible transformation of photochromic compounds.
Innovation Solution
A curable photochromic composition comprising a photochromic compound, a segmented polymer with (meth)acrylic polymer segments and polycarbonate, polyester, or polyurethane segments, and a curing agent with reactive functional groups, such as polyisocyanate, to form a crosslinked network that balances hardness and 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 of photochromic compound is faster, but the hardness of the film is reduced
Solution Approach 1:
The polymer matrix is segmented into multiple functional segments: (meth)acrylic polymer segments that provide softness and fast kinetics, and polycarbonate/polyester/polyurethane segments that provide hardness. This segmentation allows each segment to fulfill its specific function without compromising the other, resolving the contradiction between softness for kinetics and hardness for durability.
Solution Approach 2:
The invention uses a composite polymer system combining different polymer types with complementary properties. The (meth)acrylic segments contribute to softness and photochromic performance, while the polycarbonate/polyester/polyurethane segments contribute to hardness and mechanical strength, creating a composite matrix that balances both requirements.
2Strength
If a hard matrix is used in the cured photochromic film, then the hardness of the film is increased, but the kinetics of reversible transformation of photochromic compound is slower
Solution Approach 1:
The polymer matrix is segmented into multiple functional segments: (meth)acrylic polymer segments that provide softness and fast kinetics, and polycarbonate/polyester/polyurethane segments that provide hardness. This segmentation allows each segment to fulfill its specific function without compromising the other, resolving the contradiction between softness for kinetics and hardness for durability.
Solution Approach 2:
The invention uses a composite polymer system combining different polymer types with complementary properties. The (meth)acrylic segments contribute to softness and photochromic performance, while the polycarbonate/polyester/polyurethane segments contribute to hardness and mechanical strength, creating a composite matrix that balances both requirements.
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 enhanced hardness and maintained photochromic performance by creating a crosslinked structure that allows for rapid transformation of photochromic compounds between states, improving the overall properties of cured photochromic layers.
Implementation Method 1
a curing agent comprising reactive functional groups that are reactive with the active hydrogen groups of the segmented polymer
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) a photochromic compound; and (b) a segmented polymer that includes active hydrogen groups, at least one first segment, and at least one second segment, in which, (i) each first segment independently includes a (meth)acrylic polymer segment, and (ii) each second segment independently includes at least one of, a polycarbonate segment, a polyester segment, a polyether segment, a polyurethane segment, and combinations of two or more thereof. The curable photochromic composition further includes (c) a curing agent having reactive functional groups that are reactive with the active hydrogen groups of the segmented polymer (a), in which the curing agent includes at least one of, a polyisocyanate, a polyisothiocyanate, and an aminoplast. The present invention also relates to photochromic articles that include at least one layer formed from the curable photochromic composition of the present invention.