Aromatic Hindered Urea Bonds for pH-Independent Polymer Degradation
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Solution Overview
Problem
Current polymers lack the desired dynamic properties and performance characteristics for applications such as drug delivery systems, tissue engineering, and environmentally friendly packaging, as they are difficult to recycle, self-heal, or degrade in a controlled manner, and existing hydrolysable polymers often have pH-dependent degradation kinetics that are not suitable for consistent cargo release across a wide pH range.
Innovation Solution
Development of polymers with aromatic-substituted hindered urea bonds (HUBs) that exhibit pH-independent hydrolytic kinetics, allowing for rapid and consistent hydrolysis from pH 2 to 11, enabling the creation of hydrolysable and degradable materials with tunable degradation profiles suitable for various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymers with strong covalent bonds are used, then structural stability and strength are improved, but recyclability and controlled degradation are worsened
Solution Approach 1:
The patent applies dynamic covalent chemistry by incorporating hindered urea bonds that can reversibly dissociate and reassociate. These bonds maintain structural integrity during use but can be dynamically broken down under specific conditions (pH, temperature), enabling controlled degradation and recyclability while preserving overall material strength.
Solution Approach 2:
The patent utilizes pH-dependent hydrolysis kinetics as a control parameter. By designing polymers with hindered urea bonds that hydrolyze at specific pH ranges, the material can be stabilized in certain environmental conditions and degraded in others, allowing controlled transformation between stable and degradable states based on environmental parameters.
2Ease of manufacture
If hydrolysable polymers are designed for controlled degradation, then recyclability is improved, but degradation consistency across pH ranges is worsened
Solution Approach 1:
The patent specifically designs hindered urea bonds with pH-independent hydrolysis kinetics. The chemical structure is engineered so that the rate-determining step for degradation is the dissociation of the hindered urea bond, which occurs at a consistent rate regardless of pH conditions. This ensures reliable and predictable degradation behavior across wide pH ranges, from acidic to basic environments.
3Adaptability or versatility
If non-covalent interactions are used for dynamic properties, then reversibility is improved, but bond strength and stability are worsened
Solution Approach 1:
The patent creates composite polymeric materials incorporating both strong covalent bonds for structural integrity and dynamic hindered urea bonds for reversibility. The hindered urea bonds act as dynamic linkages within the covalent network, providing reversible functionality while the overall covalent framework maintains material strength and stability.
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 polymers with HUBs demonstrate significantly faster urea bond dissociation rates compared to aliphatic counterparts, achieving complete degradation within minutes in aqueous solutions, maintaining stability in solid form, and providing pH-independent hydrolytic kinetics, which is crucial for applications requiring consistent cargo release and material degradation across varying pH conditions.
Implementation Method 1
These urea bonds are aryl-substituted, i.e. aromatic-substituted hindered urea bonds, that demonstrate pH independent hydrolytic kinetics, such that they consistently and rapidly hydrolyze in water from pH 2 to 11.
Data Source
AI summary
The present invention relates to polymers having dynamic urea bonds and more specifically to polymers having hindered urea bonds (HUBs) with fast hydrolytic kinetics. These urea bonds are aryl-substituted, i.e. aromatic-substituted hindered urea bonds, that demonstrate pH independent hydrolytic kinetics, such that they consistently and rapidly hydrolyze in water from pH 2 to 11. The urea bond dissociation for these materials is generally such that k−1>h−1, which is two orders of magnitudes faster than for aliphatic hindered ureas. The present invention also relates to hydrolytically reversible or degradable linear, branched or network polymers incorporating these HUBs and to precursors for incorporation of these HUBs into these polymers. The technology can be applied to and integrated into a variety of polymers, such as polyureas, polyurethanes, polyesters, polyamides, polycarbonates, polyamines, and polysaccharides to make linear, branched, and cross-linked polymers. Polymers incorporating these HUBs can be used in a wide variety of applications including for example, environmentally compatible packaging materials and biomedical applications, such as drug delivery systems and tissue engineering. In other embodiments, the HUBs can be used in self-healing polymers.