Polycarbosiloxane Monomers for Oxygen-Permeable Silicone Hydrogels
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Solution Overview
Problem
There is a need for new monomers that can produce silicone hydrogels for soft contact lenses with high oxygen permeability, suitable water content, sufficient elasticity, and comfort, as existing monomers do not fully meet the desired modulus and biocompatibility requirements.
Innovation Solution
The development of mono ethylenically unsaturated polymerizable group containing polycarbosiloxane monomers, which can be polymerized to form polymeric compositions with desirable physical characteristics, such as low modulus of elasticity and improved hydrolytic stability, by incorporating specific monomers like those described in formulas I to XVI, and their use in monomer mixes with hydrophilic and hydrophobic monomers for ophthalmic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicone macromers and cross-linkers are used to form hydrogels, then oxygen permeability is improved, but the modulus of elasticity remains too high for soft contact lenses
Solution Approach 1:
The patent changes the chemical parameters of the cross-linking monomers by using polycarbosiloxane backbones with specific structures ( formulas I-XVI) instead of conventional polysiloxane cross-linkers. This parameter change in molecular structure enables lower cross-linking density and reduced modulus while preserving oxygen permeability through the silicone-containing hydrophobic domains.
Solution Approach 2:
The patent creates composite hydrogel structures combining hydrophilic polymer networks with hydrophobic silicone-containing polycarbosiloxane domains. This composite approach allows the hydrophobic regions to maintain oxygen permeability while the hydrophilic matrix provides softness and flexibility, resolving the contradiction between oxygen transport and mechanical softness.
2Strength
If cross-linking density is increased to improve elasticity, then mechanical strength is improved, but hydrolytic stability decreases
Solution Approach 1:
The patent modifies the chemical parameters of the cross-linker molecules by introducing polycarbosiloxane structures with specific carborane or heteroatom-containing groups (formulas I-XVI). These structural parameter changes enhance hydrolytic resistance through the inherent stability of the carbosiloxane backbone while maintaining appropriate elasticity through controlled cross-linking density.
3Ease of operation
If soft and flexible materials are used for comfort, then biocompatibility is improved, but sufficient elasticity and structural integrity are compromised
Solution Approach 1:
The patent employs composite hydrogel materials combining soft hydrophilic polymer matrices with reinforced hydrophobic polycarbosiloxane cross-linker domains. The soft hydrophilic matrix provides comfort and biocompatibility, while the structured polycarbosiloxane cross-linkers maintain elasticity and structural integrity, resolving the contradiction between softness and mechanical strength.
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 hydrogel contact lenses exhibit improved oxygen permeability, comfort, and biocompatibility, with the ability to maintain these properties for extended wear without irritation, and can be used in various medical devices requiring soft and flexible materials.
Implementation Method 1
mono ethylenically unsaturated polymerizable group containing polycarbosiloxane monomers capable of polymerization to form polymeric compositions
Data Source
AI summary
Polymeric compositions useful in the manufacture of biocompatible medical devices. More particularly, it relates to certain monoethylenically unsaturated polymerizable group containing polycarbosiloxane monomers capable of polymerization to form polymeric compositions having desirable physical characteristics useful in the manufacture of ophthalmic devices.