Polyurethane Stent Bonding via SiO2 Adhesion Layers
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Solution Overview
Problem
The durable bonding of polyurethane polymers to stent frames, especially under cyclic mechanical stresses and for biomedical implants like heart valves, is challenging due to embedding issues that affect the implant's compatibility and delivery.
Innovation Solution
A multi-layered adhesion method involving the deposition of an SiO2 layer, followed by hydroxysilane and urethane (meth)acrylate compounds, and finally a polyurethane (meth)acrylate compound, to form a strong bond between the polyurethane polymer and the substrate, ensuring the polymer can withstand dynamic and cyclical loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a spray coating process is used to form the prosthetic heart valve by coating the frame and leaflet form together, then the manufacturing process is simplified, but the frame structure becomes embedded in the polymer base which increases the foreign material surface area and complicates catheter delivery
Solution Approach 1:
The invention divides the coating process into separate stages: first coating the frame structure, then separately forming and attaching the leaflet form. This segmentation prevents the frame from being embedded in the polymer base while still achieving complete coverage, thereby maintaining ease of manufacture without compromising delivery capability.
Solution Approach 2:
The frame is pre-coated with polymer material before the leaflet form is attached. This preliminary action ensures that the frame surface is prepared for subsequent leaflet attachment while maintaining frame visibility and accessibility, avoiding embedding issues that would complicate catheter delivery.
2Strength
If the frame is embedded in the polymer base to increase coverage, then the structural integrity is improved, but the actual frame is not discernible which increases foreign material surface area and affects body acceptance
Solution Approach 1:
The invention applies polymer coating selectively: the frame structure receives a initial coating layer that maintains its discernibility, while the leaflet form receives the primary polymer coverage. This local differentiation ensures structural integrity through adequate coating while minimizing unnecessary foreign material surface area exposure.
3Reliability
If more polymer base material is present to ensure complete coverage, then the bonding durability is improved, but the implant becomes more difficult to compress for catheter delivery
Solution Approach 1:
The invention applies polymer coating in controlled amounts: sufficient to ensure complete coverage and durable bonding between frame and leaflet form, but not excessive to the point of impeding compression. The separate formation and attachment process allows precise control of polymer quantity, achieving reliability without compromising deliverability.
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 method achieves a robust and durable bond that enhances the mechanical performance of biomedical implants, improving their compatibility and ease of delivery, with the polyurethane polymer layer effectively adhering to the substrate without embedding the frame, thus maintaining structural integrity under cyclic loads.
Implementation Method 1
depositing an SiO2 layer onto the substrate
Implementation Method 2
subjecting to conditions suitable to at least partially effect a condensation reaction between Si-OH groups of the SiO2 layer and the hydroxysilane compound
Implementation Method 3
subjecting to conditions suitable to at least partially effect a reaction between the carbon-carbon double bonds present in the first adhesive layer and the urethane (meth)acrylate compound
Implementation Method 4
subjecting to conditions suitable to at least partially effect a reaction between the (meth)acrylate groups and/or carbon radicals present in the second adhesive layer and the polyurethane (meth)acrylate compound
Data Source
Figure 1a~1c
Figure 1d~1e
Figure 2~3
AI summary
The present invention relates to a method for bonding a polyurethane polymer to a substrate using a multi-layered adhesion approach. Steps of the method include A) selecting a polyurethane polymer to be bonded to the substrate (100); B) depositing an SiO2 layer (200) onto the substrate (100); C) contacting the SiO2 layer (200) with a hydroxysilane compound, thereby forming a first adhesive layer (300) bonded to the SiO2 layer (200); D) contacting the first adhesive layer (300) with a urethane (meth)acrylate compound, thereby forming a second adhesive layer (400) bonded to the first adhesive layer (300); E) contacting the second adhesive layer (400) with a polyurethane (meth)acrylate compound, thereby forming a third adhesive layer (500) bonded to the second adhesive layer (400); F) contacting the third adhesive layer (500) with the polyurethane polymer selected in step A); G) solidifying the polyurethane polymer of step F). The invention further relates to an article obtainable by the method according to the invention, in particular a biomedical implant such as a heart valve stent.