Triblock Copolymer Biostable Foam for Gastric Applications
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Solution Overview
Problem
Current polyurethane foams face challenges in biostability, particularly in gastric environments due to hydrolytic degradation and limited mechanical properties, as they lack robust soft segments that can form effective hydrogen bonds and are incompatible with aqueous reagents.
Innovation Solution
A triblock copolymer system is introduced, where polyether, polyester, or fluoropolymer chains are chemically interspersed between urethane and urea linkages, forming a pre-formed soft segment that enhances hydrolytic stability and mechanical properties, allowing for the creation of viscoelastic biostable foams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophobic soft segments are used to improve biostability, then resistance to hydrolytic degradation is improved, but hydrogen bonding ability deteriorates leading to poor tensile strength
Solution Approach 1:
The patent uses a composite soft segment structure combining polyether (hydrophilic, hydrogen-bonding) and polysiloxane (hydrophobic, biostable) components in an ABA triblock copolymer. This composite structure allows the material to simultaneously achieve both hydrogen bonding capability for tensile strength and hydrophobicity for biostability, resolving the contradiction between these two properties.
2Strength
If polyether soft segments are used to improve mechanical properties through hydrogen bonding, then tensile strength is improved, but hydrolytic degradation increases due to hydrophilicity
Solution Approach 1:
The patent applies local quality by concentrating the hydrophilic polyether component specifically in the terminal blocks (A blocks) of the triblock copolymer, while the central block (B block) remains hydrophobic polysiloxane. This localized arrangement allows hydrogen bonding to occur at the ends for mechanical strength, while the bulk remains hydrophobic for biostability, resolving the contradiction between these properties.
3Strength
If aromatic diisocyanates are used to improve mechanical reinforcement, then tensile properties are improved, but biostability deteriorates due to chemical lability
Solution Approach 1:
The patent changes the chemical parameter of the diisocyanate from aromatic to aliphatic type. Aliphatic diisocyanates form urethane linkages that are chemically more stable and resistant to hydrolytic degradation compared to aromatic diisocyanates, while still providing adequate mechanical reinforcement. This parameter change resolves the contradiction between tensile properties and biostability.
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 triblock copolymer foams exhibit improved stability in gastric fluid, maintaining mechanical integrity and low water uptake, with enhanced elongation capacity and tensile strength, making them suitable for prolonged use in gastrointestinal applications.
Implementation Method 1
PEO and to a much lesser extent PPO can facilitate additional hydrogen bonding between segments thus yielding improved mechanical characteristics
Implementation Method 2
because many of the newer soft segment materials do not hydrogen bond well they lack mechanical characteristics which are desirable for some applications
Data Source
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AI summary
The present invention provides a triblock copolymer and a viscoelastic biostable foam comprising the same.