Elastic Moisture-Permeable Films via Block Copolymer Blends
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Solution Overview
Problem
Existing breathable materials, such as fabrics and coatings, face challenges in achieving a balance between moisture-vapor permeability and durability, particularly in applications requiring elasticity and resistance to repeated stretching without compromising water-permeability.
Innovation Solution
The development of films comprising a combination of elastomeric styrenic block copolymers, optionally functionalized with functional groups other than sulfonic acid or sulfonate ester groups, and sulfonated block copolymers, which are formulated to maintain moisture-vapor permeability while ensuring high durability and elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If breathable materials incorporate a continuous polymer film to achieve moisture-vapor permeability, then moisture-vapor transmission is improved, but durability and resistance to repeated stretching are compromised
Solution Approach 1:
The patent employs microporous polymer films with controlled pore structures that allow moisture-vapor transmission while maintaining mechanical integrity. The porous architecture enables selective permeability to water vapor molecules while the polymer matrix provides structural strength and elasticity for repeated stretching cycles.
Solution Approach 2:
The invention uses composite polymer systems combining hydrophilic polymers with microporous structures, and in some embodiments, combines multiple polymer layers with different functions (base coat, intermediate coats, top coat) to achieve both breathability and durability simultaneously.
2Strength
If polymer films are made more durable through cross-linking or additional layers, then strength and resistance to rubbing are improved, but moisture-vapor permeability decreases
Solution Approach 1:
The patent maintains microporous structures throughout the film architecture, including in cross-linked regions, ensuring that durability enhancements do not block moisture-vapor pathways. The porous network allows vapor transmission while the cross-linked polymer matrix provides rub-off resistance.
Solution Approach 2:
The invention divides the coating into multiple functional layers (base coat, intermediate coats, top coat) where each layer can be optimized for specific properties. Cross-linking and durability enhancements are applied selectively to outer layers while inner layers maintain open porous structures for vapor transmission.
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 films exhibit improved stretchability, light-weight, and resistance to rub-off, maintaining water-permeability even after repeated stretching, making them suitable for diverse applications including breathable clothing and medical applications.
Implementation Method 1
The moisture-vapor permeability of the polymer membrane is sufficient to allow sensible and insensible perspiration to diffuse away from the body
Implementation Method 2
Styrenic block copolymers can comprise internal polymer blocks and terminal end polymer blocks comprising chemically different monomer types thereby providing particular desirable properties
Data Source
Figure 1~2
AI summary
The present disclosure relates to films such as membranes and coatings and to coated articles. The films comprise a combination of at least one elastomeric styrenic block copolymer which is optionally functionalized with functional groups different from sulfonic acid or sulfonate ester functional groups, and at least one sulfonated block copolymer. Films comprising the optionally functionalized block copolymer(s) and the additional sulfonated block copolymer(s) are elastic and are moisture-vapor permeable, and thus useful as coatings in breathable clothing and footwear, industrial workwear including cleanroom coveralls, in medical applications such as wound dressings and protective clothing, for bed sheets and mattress or seat covers, and other non-apparel applications.