Polyurethane Foam Sponge for Wound Dressing Vapor Permeability
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Solution Overview
Problem
Self-adherent silicone foam and polyurethane wound dressings have low vapor permeability, leading to wound infiltration and allergy issues, necessitating frequent replacement and debridement.
Innovation Solution
A polyurethane foam sponge is produced by reacting a hydrophobic polyol with a hydrophilic diisocyanate to form a prepolymer, which is then mixed with a hydrophilic polyether polyol, a blowing agent, an end-capping agent, and a reinforcing agent, creating a microphase-separated structure that allows for vapor permeability and is integrated into a wound dressing with a waterproof and vapor-permeable carrier sheet and adhesive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-adherent silicone foam or polyurethane wound dressings are used, then wound protection and contamination prevention are improved, but vapor permeability deteriorates leading to wound infiltration and allergy
Solution Approach 1:
The patent applies local quality by creating a microphase-separated structure within the polyurethane foam sponge, where hydrophobic regions provide structural integrity and wound protection, while hydrophilic regions create vapor-permeable pathways that prevent wound infiltration and allergy. This localized differentiation of material properties within the same dressing allows simultaneous achievement of protection and vapor permeability.
Solution Approach 2:
The patent employs composite materials by combining hydrophobic polyol segments with hydrophilic diisocyanate segments within the polyurethane foam matrix. This creates a composite structure where the hydrophobic regions maintain dressing integrity while the hydrophilic regions facilitate vapor transmission, resolving the contradiction between protection and vapor permeability.
2Strength
If traditional polyurethane foam sponge is used, then structural integrity is maintained, but vapor permeability is insufficient causing frequent replacement
Solution Approach 1:
The patent applies local quality by creating a microphase-separated structure within the polyurethane foam sponge, where hydrophobic regions provide structural integrity and wound protection, while hydrophilic regions create vapor-permeable pathways that prevent wound infiltration and allergy. This localized differentiation of material properties within the same dressing allows simultaneous achievement of protection and vapor permeability.
Solution Approach 2:
The patent employs parameter changes by carefully controlling the molecular weight ratios of hydrophobic polyol (400-2000 g/mol) and hydrophilic diisocyanate (100-1000 g/mol) to optimize the balance between structural integrity and vapor permeability. By adjusting these parameters, the foam maintains strength while achieving sufficient vapor transmission to prevent wound infiltration.
3Device complexity
If low vapor permeability materials are used, then material simplicity is maintained, but skin infiltration and allergy increase
Solution Approach 1:
The patent applies local quality by creating a microphase-separated structure within the polyurethane foam sponge, where hydrophobic regions provide structural integrity and wound protection, while hydrophilic regions create vapor-permeable pathways that prevent wound infiltration and allergy. This localized differentiation of material properties within the same dressing allows simultaneous achievement of protection and vapor permeability.
Solution Approach 2:
The patent uses the polyether polyol as an intermediary substance that facilitates the formation of hydrophilic pathways within the foam structure. This intermediary component enables vapor transmission without compromising the overall structural integrity of the dressing, thereby preventing skin infiltration while maintaining material feasibility.
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 polyurethane foam sponge enhances vapor permeability and moisture retention, reducing skin infiltration and promoting wound healing by effectively managing wound exudate, as demonstrated by higher water vapor transmission rates and lower skin infiltration compared to traditional dressings.
Implementation Method 1
the polyurethane foam sponge enhances vapor permeability and moisture retention, reducing skin infiltration
Implementation Method 2
the polyurethane foam sponge enhances vapor permeability and moisture retention, reducing skin infiltration
Data Source
AI summary
Disclosed herein is a polyurethane foam sponge produced by the steps of a) providing an hydrophobic polyol which has six hydroxyl groups, b) providing a hydrophilic diisocyanate obtained by reacting a diisocyanate with a hydrophilic polyether diol, c) reacting the hydrophobic polyol with the hydrophilic diisocyanate to obtain a prepolymer which includes 3 to 6 isocyanate groups, and d) mixing the prepolymer with a hydrophilic polyether polyol, a blowing agent, an end-capping agent, a reinforcing agent, and a catalyst to obtain the polyurethane foam sponge. A wound dressing including the polyurethane foam sponge is also disclosed.