Dynamic Diol Monomers for Reprocessable Polyurethane Vitrimers
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Solution Overview
Problem
Thermoset polymeric materials are inflexible and cannot be reprocessed or recycled, leading to significant plastic waste accumulation and limited sustainability in manufacturing systems.
Innovation Solution
Development of diol-containing monomers with dynamic conjugate acceptor (DCA) groups that enable the formation of reprocessable polyurethane vitrimers through dynamic covalent crosslinks, allowing for reprocessing, remolding, and selective degradation into high-value byproducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional thermoset polymeric materials are used, then mechanical strength and thermal stability are improved, but reprocessability and recyclability deteriorate
Solution Approach 1:
The patent applies dynamics by incorporating dynamic covalent bonds (transesterification bonds) into the thermoset polymer network. These bonds can reversibly break and reform under specific conditions (temperature, catalyst), transforming the static crosslinked structure into a dynamic one that allows chain mobility and reprocessing while maintaining mechanical integrity during use. This enables the material to switch between a rigid state for strength and a mobile state for reprocessing.
Solution Approach 2:
The patent utilizes parameter changes by modifying the chemical state of the polymer network through controlled transesterification reactions. By changing temperature and catalyst presence, the bond exchange activity is controlled, allowing the material to transition between a stable crosslinked state (for mechanical strength) and a reactive exchange state (for reprocessing and recycling). This parameter control enables both contradictory properties to coexist under different conditions.
2Strength
If traditional thermoset polymeric materials are used, then mechanical strength and chemical resistance are improved, but sustainability and recyclability deteriorate
Solution Approach 1:
The patent implements discarding and recovering by enabling the selective degradation and recovery of polymer chains through controlled transesterification. The dynamic bonds allow the material to be broken down into recoverable oligomers or monomers under specific conditions, which can then be reused to synthesize new polymer materials. This closes the material loop and eliminates waste accumulation while maintaining mechanical performance.
Solution Approach 2:
The patent uses a catalyst as an intermediary to mediate the transesterification reactions that enable recycling. The catalyst facilitates bond exchange and selective degradation without being consumed, allowing the polymer network to be dynamically reconfigured or decomposed into recoverable components. This intermediary enables the transition from a permanent structure to a recyclable system while preserving mechanical properties.
3Adaptability or versatility
If dynamic covalent bonds are incorporated to enable reprocessing, then reprocessability is improved, but manufacturing complexity deteriorates
Solution Approach 1:
The patent applies self-service by designing a system where the polymer chains themselves perform the reprocessing function through spontaneous transesterification reactions. The dynamic covalent bonds automatically exchange and reconfigure under mild conditions without requiring external energy input or complex processing equipment. The material self-regulates its structure through bond exchange, simplifying manufacturing while enabling reprocessing.
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 vitrimers exhibit improved mechanical properties and can be recycled effectively, reducing waste and increasing the sustainability of thermoset materials without compromising performance.
Implementation Method 1
dynamic covalent crosslinks, allowing for reprocessing, remolding
Implementation Method 2
contacting a polyurethane comprising repeating units derived from the diol-containing monomer with a decoupling agent under conditions effective to provide a polyurethane degradation product
Data Source
AI summary
A diol-containing monomer has the structurewherein X is independently at each occurrence sulfur (—S—) or nitrogen (—NH—); R is independently at each occurrence a C1-12 alkylene group, a C6-20 arylene group, a C6-20 alkylarylene group, or a group of the formula —(CH2CH2O)yCH2CH2—, wherein y is 1 to 4; and EWG is an electron withdrawing group. The diol-containing monomer can be particularly useful in the preparation of polyurethanes, which can be reprocessable. A method of recycling a polyurethane having repeating units derived from the diol-containing monomer is also disclosed.