Hydrogen Bonded Hydrogels Reversible Cross-Linking
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Solution Overview
Problem
Current hydrogels face challenges in being reversibly gelled in water, lacking tunable mechanical properties, and biodegradability, often requiring toxic chemicals and crystalline domains for processing and administration.
Innovation Solution
Development of hydrogels with hydrophilic polymers covalently attached to quadruple hydrogen bonding units (4H-units) that allow for reversible supramolecular interactions, enabling easy processing and tunable mechanical properties without chemical cross-linking or large hydrophobic blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chemical cross-linking is used to form hydrogels, then mechanical strength is improved, but reversibility and biodegradability are lost
Solution Approach 1:
The patent replaces chemical cross-linking mechanisms with physical cross-linking through hydrogen bonding. The hydrophilic polymer chains form reversible physical cross-links via hydrogen bonds between carbonyl groups and amine groups, eliminating the need for irreversible chemical bonds while maintaining mechanical integrity. This substitution allows the hydrogel to be mechanically strong yet reversible and biodegradable.
Solution Approach 2:
The patent utilizes changes in physical parameters (temperature, pH) to control the hydrogen bonding interactions. By adjusting these parameters, the hydrogel can transition between gelled and sol states reversibly. The mechanical properties can be tuned by modifying the concentration of polymer, the strength of hydrogen bonding interactions, and the environmental conditions, providing versatility without chemical cross-linking.
2Adaptability or versatility
If physical cross-linking through hydrogen bonds is used, then reversibility and processability are improved, but mechanical strength is reduced
Solution Approach 1:
The patent creates a composite structure where hydrophilic polymer chains are combined with hydrophobic blocks. The hydrophobic blocks aggregate to form physical cross-links that reinforce the hydrogel network, while the hydrophilic regions maintain water solubility and enable hydrogen bonding. This composite architecture provides both mechanical strength from the hydrophobic domains and reversibility from the hydrophilic hydrogen-bonding regions.
Solution Approach 2:
The patent segments the polymer structure into distinct hydrophilic and hydrophobic blocks. The hydrophilic blocks contain carbonyl and amine groups for hydrogen bonding and water interaction, while the hydrophobic blocks provide structural reinforcement through aggregation. This segmentation allows each block to contribute its specific properties, achieving both strength and reversibility simultaneously.
3Strength
If hydrophobic blocks are used to provide mechanical strength, then strength is improved, but biodegradability and tunability are limited
Solution Approach 1:
The patent employs parameter changes in the composition and structure of hydrophilic polymers to achieve tunability. By varying the molecular weight, functional group concentration, and polymer composition, the mechanical properties, degradation rate, and gelation behavior can be precisely controlled. This approach provides versatility without relying on fixed hydrophobic block structures, enabling both strength and tunable biodegradability.
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 hydrogels can switch between gelled and liquid states reversibly, facilitating easy processing and administration, while offering a wide range of mechanical properties and optional biodegradability, enhancing their applicability in various fields.
Implementation Method 1
hydrogen bonding units are covalently attached so that they are physically or non-covalently cross-linked in a reversible supramolecular way by hydrogen bonds
Data Source
AI summary
The present invention relates to new hydrogel materials using water gellants that are comprised by hydrophilic polymers to which hydrogen bonding units are covalently attached. Optionally, the hydrogel contains additional ingredients or additives. These new reversible hydrogels can easily be fine-tuned in their mechanical performance and functionality and are especially suitable for cosmetic and biomedical applications.