Sulfur Modified Silanes for High Refractive Index Coatings
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Solution Overview
Problem
Current high refractive index coatings for ophthalmic lenses have low mechanical properties and are unsuitable for high index lenses due to significant differences in refractive index between the lens substrate and coatings, leading to unsightly fringes and brittleness when high refractive index nanoparticles are added.
Innovation Solution
A process involving the mixing of a polythiol and an alkenyl silane, followed by thiol-ene addition under UV radiation or heat, to produce polysulfide polysilanes with refractive indices ranging from 1.47 to 1.55, which are then hydrolyzed to form high refractive index coatings with improved mechanical properties and reduced haze.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high refractive index nanoparticles (TiO2 or ZrO2) are added to increase coating refractive index, then refractive index is improved, but mechanical properties deteriorate due to brittleness
Solution Approach 1:
The invention changes the chemical composition parameters of the coating matrix by incorporating sulfur-modified silanes with specific refractive index contributions. This allows achieving high refractive index (1.60-1.68) through molecular-level composition control rather than nanoparticle addition, thereby maintaining mechanical integrity while meeting optical requirements
Solution Approach 2:
The invention creates a hybrid organic-inorganic composite coating system combining silane-based organic matrix with inorganic crosslinking networks. This composite structure achieves both high refractive index and improved mechanical properties through synergistic interaction between organic flexibility and inorganic strength, avoiding the brittleness associated with nanoparticle-reinforced coatings
2Strength
If conventional coatings with low refractive index (about 1.50) are used, then mechanical properties are maintained, but unsightly fringes occur due to large difference with lens substrate refractive index
Solution Approach 1:
The invention modifies the refractive index parameter of the coating material by incorporating sulfur-containing functional groups and optimizing silane composition ratios. This increases the coating refractive index to 1.60-1.68, reducing the refractive index mismatch with high-index lens substrates (1.67-1.80) and thereby minimizing fringing effects while preserving mechanical properties
3Strength
If inorganic nanoparticles are added to organic polymers to improve mechanical properties, then strength is improved, but haze increases due to nanoparticle aggregation
Solution Approach 1:
The invention extracts and eliminates the need for inorganic nanoparticle reinforcement by using sulfur-modified silanes that inherently provide both mechanical strength and high refractive index at the molecular level. This removes the source of nanoparticle aggregation and associated haze problems while maintaining improved mechanical properties through chemical crosslinking
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 polysulfide polysilane coatings achieve refractive indices between 1.59 and 1.67, offering improved mechanical properties and reduced haze, making them suitable for high index lenses with minimal fringing and increased abrasion resistance.
Implementation Method 1
exposing the solution to UV radiation or heat, preferably by UV radiation, to undergo thiol-ene addition thereby producing a polysulfide polysilane
Implementation Method 2
exposing the solution to UV radiation or heat, preferably by UV radiation, to undergo thiol-ene addition
Implementation Method 3
which are then hydrolyzed to form high refractive index coatings with improved mechanical properties and reduced haze
Data Source
AI summary
A composition having a polysulfide polysilane formed by the reaction of a polythiol and an alkenyl silane. The reactants are combined in a thiol-ene addition process driven by UV radiation or heat, preferably by UV radiation. The polysulfide polysilane is then hydrolyzed and may be combined with other hydrolyzed compounds. For coatings, the polysulfide polysilane is hydrolyzed and may optionally be combined with nanoparticles. For bulk materials, the polysulfide polysilane is hydrolyzed, concentrated and heated to form a high refractive index material which can be used to form lenses.