Self-Healing Elastomeric Film via Core-Shell Latex
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Solution Overview
Problem
Elastomeric films, particularly in dip-molding applications, lack self-healing properties and recyclability due to irreversible crosslinks, leading to waste and material failures.
Innovation Solution
Development of an aqueous dispersion comprising core-shell polymer latex particles with a crosslinked shell and non-crosslinked core, where the shell bears ethylenically unsaturated groups separated by at least three chemical bonds, allowing for self-healing and shape retention properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional sulfur vulcanization systems or crosslinkers are used to achieve crosslinked elastomeric films, then mechanical strength is improved, but self-healing properties and recyclability are lost
Solution Approach 1:
The patent changes the chemical nature of crosslinks from irreversible covalent bonds (sulfur vulcanization) to reversible supramolecular interactions (hydrogen bonds, metal coordination, ionic interactions). This parameter change in bonding mechanism allows the material to maintain mechanical strength while enabling self-healing through reversible bond formation and dissociation.
Solution Approach 2:
The invention creates a composite crosslinking system combining permanent covalent crosslinks (for structural integrity) with reversible supramolecular crosslinks (for self-healing). This composite approach integrates both strong mechanical properties and self-repair capabilities in a single elastomeric film system.
2Strength
If irreversible crosslinks are used in elastomeric films, then mechanical strength is improved, but recyclability is lost
Solution Approach 1:
The patent transforms the crosslinking mechanism from irreversible chemical bonds to reversible supramolecular interactions, enabling the elastomeric film to be reprocessed and recycled while maintaining adequate mechanical strength through the reversible nature of hydrogen bonds, metal coordination, and ionic interactions.
3Strength
If sulfur crosslinks are used to achieve crosslinked elastomeric films, then mechanical strength is improved, but allergic reactions are caused
Solution Approach 1:
The patent extracts and eliminates sulfur and sulfur-based accelerators from the crosslinking system, replacing them with alternative crosslinking mechanisms such as metal coordination (zinc oxide, calcium carbonate), hydrogen bonding, and ionic interactions, thereby removing the source of Type IV allergic reactions while maintaining crosslinking functionality.
Solution Approach 2:
The invention changes the crosslinking chemistry from sulfur-based covalent bonds to alternative mechanisms including metal coordination, hydrogen bonding, and ionic interactions, eliminating allergenic sulfur compounds while achieving the desired mechanical strength through these alternative crosslinking pathways.
4Strength
If crosslinked elastomeric films are produced, then mechanical strength is improved, but defect repair capability is lost
Solution Approach 1:
The patent modifies the crosslinking mechanism from irreversible covalent bonds to reversible supramolecular interactions, enabling the elastomeric film to autonomously repair defects such as pinholes and cracks through the dynamic formation and reformation of hydrogen bonds, metal coordination, and ionic interactions under service conditions.
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 solution enables the production of self-supported elastomeric films with self-healing and shape retention capabilities, reducing waste and avoiding the use of sulfur crosslinks, thus enhancing the environmental sustainability and performance of elastomeric films.
Implementation Method 1
The present invention also relates to a method for making an aqueous dispersion comprising core-shell polymer latex particles... by emulsion polymerization comprising at least two steps
Implementation Method 2
the shell of the core-shell particles is crosslinked and the core of the core-shell particles is not crosslinked
Data Source
AI summary
The present invention relates to an aqueous dispersion comprising core-shell polymer latex particles wherein the shell of the core-shell polymer latex particles bears ethylenically unsaturated groups pending from the polymeric backbone of the shell of the latex particles wherein the ethylenic unsaturation is separated from the polymeric backbone by at least 3 chemical bonds and wherein the shell of the core-shell particles is cross-linked and the core of the core-shell particles is not crosslinked, to a method for making the aqueous dispersion, to an elastomeric film made from the aqueous dispersion, to an article comprising the elastomeric film and to a method for making a self-supported elastomeric film from the aqueous dispersion.