Photo-Induced Step-Growth Polymerization for Hydrogel Contact Lenses
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Solution Overview
Problem
Current methods for manufacturing hydrogel contact lenses face challenges in producing durable, highly elastic lenses with desired mechanical and physical properties, particularly due to limitations in molecular mass and viscosity of prepolymer compositions, which affect mechanical strength and processing efficiency.
Innovation Solution
A method involving photo-induced step-growth polymerization is employed, using prepolymers with multiple propagating groups capable of crosslinking under actinic irradiation, forming hydrogel materials without vinylic monomers, and utilizing reusable molds for precise and efficient lens production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a prepolymer with low molecular mass is used to achieve low viscosity for high-speed dispensing, then processing efficiency is improved, but mechanical strength such as tear resistance deteriorates
Solution Approach 1:
The invention changes the molecular mass parameter of the prepolymer to a specific range (10,000-100,000 g/mol) that optimizes both viscosity and mechanical strength, and adjusts the functional group content parameter (0.1-10 mmol/g) to control crosslinking density and final lens strength
Solution Approach 2:
The invention creates a composite system combining prepolymer with specific molecular mass characteristics and functional groups that undergo photo-induced step-growth polymerization, resulting in a hydrogel material that achieves both processability and mechanical strength
2Speed
If traditional free radical chain-growth polymerization is used, then curing speed is fast, but mechanical strength and elasticity of the lens deteriorates
Solution Approach 1:
The invention substitutes free radical chain-growth polymerization mechanism with photo-induced step-growth polymerization mechanism, replacing the chemical reaction pathway to achieve both fast curing and superior mechanical properties through different polymerization kinetics and network formation
Solution Approach 2:
The invention changes the polymerization mechanism parameter from chain-growth to step-growth, and introduces photo-induced initiation that maintains fast curing speed while the step-growth mechanism inherently produces better mechanical strength and elasticity
3Device complexity
If disposable plastic molds are used for lens production, then manufacturing complexity is reduced, but manufacturing precision and lens fidelity deteriorate
Solution Approach 1:
The invention uses disposable plastic molds that are inexpensive and single-use, eliminating the need for complex cleaning and maintenance procedures associated with reusable molds, while still achieving acceptable precision for mass production
Solution Approach 2:
The invention uses molds with precise surface geometries that copy the desired lens design onto the contact lens during casting, achieving high fidelity through the mold's precise surface replication rather than through complex mold management
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
This approach enhances mechanical strength, such as tear resistance, while maintaining low viscosity for efficient processing, allowing for the production of contact lenses with tailored mechanical and physical properties, and eliminates the need for subsequent purification steps.
Implementation Method 1
at least one prepolymer having multiple first propagating groups each capable of undergoing photo-induced step-growth polymerization in the presence of or in the absence of a step-growth-propagating agent
Implementation Method 2
actinically irradiating or thermally curing the composition in the mold to crosslink said at least one prepolymer to form the contact lens
Data Source
AI summary
The invention provide a new lens curing method for making hydrogel contact lenses. The new lens curing method is based on actinically-induced step-growth polymerization. The invention also provides hydrogel contact lenses prepared from the method of the invention and fluid compositions for making hydrogel contact lenses based on the new lens curing method. In addition, the invention provide prepolymers capable of undergoing actinically-induced step-growth polymerization to form hydrogel contact lenses.