Silicone Hydrogel Contact Lens Surfaces for Direct Hydrophilic Coating
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Solution Overview
Problem
There is a need for a more efficient method to produce silicone hydrogel contact lenses with a high concentration of primary amino groups on the surface for covalent attachment of water-soluble hydrophilic polymers without the step of forming an anchor layer, and to enhance production efficiency.
Innovation Solution
A method involving a polymerizable composition containing N-Boc-containing vinylic monomers is used to create silicone hydrogel contact lenses, which are then treated with a pH-adjusted liquid medium to convert Boc-protected amino groups into primary amino groups, enabling direct attachment of hydrophilic polymers during autoclave.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyanionic polymer anchoring layer is formed by dipping before covalent attachment of hydrophilic polymer, then the attachment can proceed effectively, but the manufacturing process becomes complex and production efficiency is reduced
Solution Approach 1:
The silicone-containing polymerizable component with pendant vinyl groups is incorporated into the contact lens matrix during the initial polymerization process, pre-positioning the reactive groups before the hydrophilic polymer attachment step. This eliminates the need for separate anchoring layer formation by dipping, simplifying the manufacturing process while ensuring effective covalent attachment
Solution Approach 2:
The invention merges the anchoring function and the matrix structure into a single integrated system. The silicone-containing polymerizable component serves dual purposes: forming the oxygen-permeable matrix and providing pendant vinyl groups for hydrophilic polymer attachment, thereby eliminating the separate polyanionic polymer anchoring layer and reducing manufacturing complexity
2Reliability
If a polyanionic polymer anchoring layer is formed by dipping before covalent attachment of hydrophilic polymer, then the attachment can proceed effectively, but production efficiency is reduced due to additional processing steps
Solution Approach 1:
The silicone-containing polymerizable component with pendant vinyl groups is incorporated into the contact lens matrix during the initial polymerization process, pre-positioning the reactive groups before the hydrophilic polymer attachment step. This eliminates the need for separate anchoring layer formation by dipping, simplifying the manufacturing process while ensuring effective covalent attachment
Solution Approach 2:
The invention extracts and eliminates the separate polyanionic polymer anchoring layer formation step from the manufacturing process. By incorporating the anchoring functionality directly into the matrix-forming silicone-containing polymerizable component, the process is simplified to require only the essential steps of polymerization and hydrophilic polymer attachment, thereby improving production efficiency
3Productivity
If silicone hydrogel contact lenses are produced without an anchor layer formation step, then production efficiency is improved, but achieving high surface concentration of primary amino groups for effective hydrophilic polymer attachment becomes difficult
Solution Approach 1:
The silicone-containing polymerizable component is designed with pendant vinyl groups that are distributed throughout the matrix but can migrate or react preferentially at the surface during the polymerization and subsequent hydrophilic polymer attachment processes. This local concentration mechanism ensures high surface amino group concentration without requiring a separate anchoring layer formation step
Solution Approach 2:
The invention utilizes changes in the chemical state and reactivity of the silicone-containing polymerizable component during polymerization. The pendant vinyl groups undergo polymerization and subsequent reaction with hydrophilic polymer, transforming from unreactive side chains to reactive anchoring sites, thereby achieving high surface amino group concentration through parameter changes rather than physical layer formation
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 method results in silicone hydrogel contact lenses with a high concentration of primary amino groups, allowing direct coating without an anchor layer, enhancing production efficiency and lens compatibility with the ocular environment.
Implementation Method 1
curing thermally or actinically the polymerizable composition in the lens mold to form a silicone hydrogel contact lens precursor
Implementation Method 2
removing Boc groups from the N-Boc-containing repeating units by immersing the silicone hydrogel contact lens precursor in a liquid medium having a pH of about 4 or less for a time period sufficient to obtain the silicone hydrogel contact lenses comprising amino-containing repeating units each having a primary amino group
Data Source
AI summary
The present invention generally relates to silicone hydrogel contact lenses each inherently having, on lens surfaces, a relatively-high concentration of primary amino groups and to a method for producing the same. The invention is also related to silicone hydrogel contact lens precursors each inherently having, on lens surfaces, a relatively-high concentration of N-Boc-protected primary amino groups which can be easily and conveniently deprotected during lens extraction and/or hydration steps.