Chain Extender with Disulfide and Imine Bonds for Polyurethane Repair
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Solution Overview
Problem
Existing recyclable thermosetting polyurethane materials prepared with chain extenders containing dynamic covalent bonds have poor repair efficiency during hot-pressing, limiting their recycling and reuse.
Innovation Solution
A chain extender with a chemical formula containing two disulfide bonds and two imine bonds, prepared by mixing 4,4′-dithiodianiline and glutaraldehyde through an aldimine condensation reaction, is used to enhance the hot-pressing repair efficiency of thermosetting polyurethane materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If chain extenders containing dynamic covalent bonds (such as disulfide bonds) are used to enable recycling and reuse of thermosetting polyurethane through hot-pressing, then the recyclability and reuse capability are improved, but the repair efficiency during hot-pressing deteriorates
Solution Approach 1:
The patent employs a composite chain extender structure combining disulfide bonds and imine bonds. The disulfide bonds provide recyclability through exchange reactions, while the imine bonds contribute to efficient hot-pressing repair. This composite approach allows both recyclability and high repair efficiency to coexist, resolving the contradiction between these two properties.
Solution Approach 2:
The patent modifies the chemical structure parameters of the chain extender by introducing specific functional groups (disulfide and imine bonds) with particular spatial arrangements. This structural parameter change enables the material to exhibit both recyclability and enhanced repair efficiency, transforming the performance characteristics to resolve the technical contradiction.
2Ease of manufacture
If conventional chain extenders with single type of dynamic covalent bond are used, then the preparation process is simple, but the hot-pressing repair efficiency is poor
Solution Approach 1:
The patent creates a composite chain extender incorporating both disulfide bonds and imine bonds in a single molecular structure. This composite design maintains relative simplicity in preparation while dramatically improving hot-pressing repair efficiency, as demonstrated by the 97% repair efficiency compared to 59% for conventional single-bond systems.
Solution Approach 2:
The patent merges the beneficial properties of disulfide bonds (for recyclability) and imine bonds (for efficient repair) into a single chain extender molecule. This combining approach allows the material to achieve high repair efficiency without significantly complicating the preparation process, as both bonds are introduced through a unified synthesis method.
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 new chain extender significantly improves the hot-pressing repair efficiency of thermosetting polyurethane materials, achieving a repair efficiency of 97% compared to 59% with conventional methods, extending the service life of polyurethane materials.
Implementation Method 1
Mixing 4,4′-dithiodianiline, glutaraldehyde and polar organic solvents to perform aldimine condensation reaction to obtain the chain extender
Implementation Method 2
the dynamic covalent bonds at the fracture surface are used. Under the condition of hot-pressing, exchange and reconnect the polyurethane molecular chain
Data Source
AI summary
The present disclosure belongs to the technical field of polymer materials, and in particular relates to a chain extender and a preparation method and application thereof, a recyclable thermosetting polyurethane and a preparation method thereof. The present disclosure provides a chain extender whose chemical formula is shown in formula I. The chain extender provided by the present disclosure contains two types of dynamic covalent bonds, and the total number of dynamic covalent bonds is 4. The thermosetting polyurethane prepared by the provided chain extender has better hot-pressing repair efficiency. The results of the examples show that under the same hot-pressing conditions, the repair efficiency of the thermosetting polyurethane prepared by the 4,4′-dithiodianiline chain extender is 59%. The repair efficiency of thermosetting polyurethane is 97%, which is significantly improved.