Polyurethane Urea Coating Diol Crosslinking for Medical Devices
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Solution Overview
Problem
Current polyurethane urea-based coatings for medical devices intended for vascular or organ introduction lack diol crosslinking functionality, which is essential for improved lubricity and durability.
Innovation Solution
The synthesis of polyurethane urea coatings involves reacting adipic acid dihydrazide with glycidol to form a diol, optimizing reactions at lower temperatures to reduce side reactions and enhance chain extension, allowing for the formation of a diol that can further react with excess isocyanate to create a slightly crosslinked network, thereby improving lubricity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyurethane urea-based coatings are synthesized without diol crosslinking functionality, then the coating can be produced with simpler chemistry, but the lubricity and durability are insufficient for medical device applications
Solution Approach 1:
The patent incorporates diol crosslinking functionality directly into the polyurethane urea coating synthesis process, performing the crosslinking action preliminarily during coating formation rather than requiring subsequent separate crosslinking steps. This preliminary incorporation of crosslinking capability resolves the contradiction by enabling improved lubricity and durability through diol crosslinks while maintaining relatively simple one-step coating chemistry.
2Productivity
If reactions are conducted at higher temperatures to increase reaction rate, then productivity improves, but side reactions increase and chain extension is reduced
Solution Approach 1:
The patent optimizes the reaction temperature parameter to a lower range that favors chain extension and minimizes side reactions, while compensating for the reduced reaction rate through extended reaction time. This parameter change resolves the contradiction by prioritizing chain extension quality over rapid productivity, achieving the desired coating properties through controlled lower-temperature synthesis.
3Reliability
If excess isocyanate is used to ensure complete reaction, then the coating achieves better durability, but the formulation becomes less predictable and harder to control
Solution Approach 1:
The patent introduces diol as an intermediary component that reacts with isocyanate to form stable crosslinks, thereby controlling the isocyanate consumption and reaction progression. This intermediary role of diol resolves the contradiction by providing predictable formulation behavior through stoichiometric control while still achieving complete reaction and durable coating performance.
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 coatings are extremely lubricious and durable, with both hard and soft segments, providing increased physical crosslinks through hydrogen bonding, making them suitable for medical devices requiring low VOCs and enhanced mechanical properties.
Implementation Method 1
adipic acid dihydrazide where active hydrogens react with the epoxy group found on glycidol to form a diol
Implementation Method 2
providing increased physical crosslinks through hydrogen bonding
Data Source
AI summary
A coating composition containing added diol functionality to a urethane, a urea, or polyurethane urea functional resin where an adipic acid dihydrazide chain extender, or free adipic acid dihydrazide active hydrogens react with the oxirane group found in glycidol is described. The combination of diisocyanate, a polyether segment, optionally at least one polyester diol segment, optionally at least one poly(tetrahydrofuran) diol segment, optionally and at least one dimethylol propionic acid diol segment, at least one dihydrazide segment and glycidol compound introduces an increased hydrophilic structure, by diol addition, in compositions that are usable as coatings, on for example, medical devices.