Ionic Silicone Hydrogel Wettability Modulus Trade-off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing silicone hydrogels for contact lenses face challenges such as poor wettability, high modulus, hydrolytic instability, and high cost, while achieving desirable oxygen permeability and clarity remains difficult due to limitations in raw materials and formulation compositions.
Innovation Solution
The development of ionic silicone hydrogels with controlled reaction kinetics, incorporating a slow-reacting anionic component and hydrophilic monomers to balance properties like stability, haze, water content, and oxygen permeability, using a reaction mixture with specific ratios of silicone-containing and hydrophilic monomers to achieve stable modulus and wettability without surface treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If polyfunctional silicone monomers or macromers are used as crosslinking agents to improve wettability through NVP incorporation, then wettability is improved, but the modulus of the final polymer increases
Solution Approach 1:
The patent changes the chemical parameters of the monomer system by using monofunctional silicone monomers instead of polyfunctional crosslinking agents, and by incorporating specific anionic monomers (acrylic acid, methacrylic acid) at controlled concentrations (0.1-10% by weight) to achieve wettability without excessive modulus increase
Solution Approach 2:
The patent creates a composite monomer system combining silicone monomers (for oxygen permeability), NVP (for wettability), and anionic monomers (for stability and wettability enhancement), where each component contributes specific properties while balancing the overall polymer characteristics
2Use of energy by moving object
If high silicone content monomers are used to achieve desirable oxygen permeability, then oxygen permeability is improved, but clarity and hydrolytic stability deteriorate
Solution Approach 1:
The patent adjusts the silicone content parameter to an optimal range (20-60% by weight) and changes the chemical stability through anionic monomer incorporation, which provides hydrolytic stability while maintaining the oxygen permeability benefits of silicone content
3Ease of operation
If NVP is incorporated in amounts of 25-55% by weight of the monomer mix to improve wettability, then wettability is improved, but manufacturing complexity increases due to need for compatibilizing components
Solution Approach 1:
The patent extracts the compatibilizing component requirement by using monofunctional silicone monomers that do not require special compatibilizers, and by incorporating anionic monomers that provide both wettability enhancement and stability without adding formulation complexity
Solution Approach 2:
The anionic monomers serve multiple functions simultaneously: they enhance wettability, provide hydrolytic stability, and act as natural compatibilizers for the NVP-silicone system, eliminating the need for separate compatibilizing components
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 silicone hydrogels exhibit improved stability, low modulus, excellent wettability, and high oxygen permeability, making them suitable for biomedical devices like contact lenses with enhanced performance and reduced manufacturing costs.
Implementation Method 1
polymers formed from reactive components comprising at least one silicone component and at least one ionic component
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to a process comprising the steps of reacting a reactive mixture comprising at least one silicone-containing component, at least one hydrophilic component, and at least one diluent to form an ophthalmic device having an advancing contact angle of less than about 80; and contacting the ophthalmic device with an aqueous extraction solution at an elevated extraction temperature, wherein said at least one diluent has a boiling point at least about 10 higher than said extraction temperature.