Reversible Polymer Crosslinkers for Acid-Triggered Substrate Recycling
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Solution Overview
Problem
Existing formaldehyde-containing crosslinkers like N-methylol acrylamide and its methacylamide analogs are cost-effective but result in less crosslinking per pound due to higher molecular weight, and there is a need for economical reversible crosslinkers to facilitate substrate recycling.
Innovation Solution
The use of acid-labile covalent crosslinking bonds formed by monomers with functional groups that break under acidic conditions, allowing separation of polymer compositions from substrates for recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If formaldehyde-containing crosslinkers like N-methylol acrylamide are used, then cost-effectiveness is improved, but crosslinking efficiency per pound decreases due to higher molecular weight
Solution Approach 1:
The patent changes the molecular weight parameter of the crosslinker by using formaldehyde-free alternatives with lower molecular weights (e.g., N-vinylformamide at 85 g/mol vs. NMA at 101 g/mol), which increases crosslinking efficiency per pound while maintaining cost-effectiveness through different synthesis routes
2Object-affected harmful factors
If formaldehyde-free crosslinkers are used, then environmental safety is improved, but cost increases due to more expensive raw materials
Solution Approach 1:
The patent employs inexpensive raw materials like acrylonitrile, vinyl acetate, and formaldehyde-free alternatives that can be readily synthesized, providing cost-effective formaldehyde-free crosslinking solutions that eliminate harmful formaldehyde content
3Reliability
If permanent crosslinking bonds are used, then coating durability is improved, but substrate recyclability deteriorates
Solution Approach 1:
The patent introduces dynamic, reversible crosslinking bonds that can form and break under different conditions. The crosslinks are stable during service to maintain durability but can be reversed using chemical agents (e.g., cysteine, dithiothreitol) or physical methods (heat, moisture) to enable substrate recycling and fiber recovery
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
Enables the economical recycling of substrates coated with polymer compositions by reversing crosslinking bonds using acidic solutions, maintaining substrate integrity and reducing waste.
Implementation Method 1
contacting the coated substrate with an acidic solution under conditions sufficient to separate the composition from the substrate, wherein at least one polymer in the polymer-containing composition is formed from at least one monomer having one or more functional groups which form acid-labile covalent crosslinking bonds
Data Source
AI summary
A method for separating a polymer-containing composition from a substrate coated with the composition is described, the method comprising contacting the coated substrate with an acidic solution under conditions sufficient to separate the composition from the substrate which can then be recycled, wherein at least one polymer present in the polymer-containing composition is formed from at least one monomer having one or more functional groups which form acid-labile (reversible) covalent crosslinking bonds with the substrate and/or with a different polymer present in the polymer-containing composition and/or with itself.