Low-Temperature Polymer Crosslinking for Hyaluronic Acid
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Solution Overview
Problem
Existing polymer-based formulations for medical and esthetic applications lack optimal rheological properties, specifically good injectability and persistence in the injection zone, due to limitations in damping capacity and plastic range, which are not effectively addressed by conventional crosslinking processes.
Innovation Solution
A crosslinking process is developed that operates at low temperatures (≤15°C) for hyaluronic acid-based formulations, optimizing the tangent of the phase angle (Tan Δ) and plastic range, achieving enhanced damping capacity and persistence while maintaining adequate rigidity and biocompatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional crosslinking processes are used at high temperatures, then crosslinking efficiency is improved, but rheological properties and plastic range deteriorate
Solution Approach 1:
The patent changes the temperature parameter from conventional high temperatures to low temperatures (≤15°C) during crosslinking. This parameter change resolves the contradiction by enabling efficient crosslinking while preserving optimal rheological properties and plastic range, as the low temperature prevents excessive rigidity and maintains the polymer's deformability.
Solution Approach 2:
The patent employs a two-stage crosslinking process with periodic action: first stage at low temperature (≤15°C) for initial crosslinking with optimal rheological properties, and second stage at elevated temperature for enhanced crosslinking efficiency. This periodic temperature variation allows the system to achieve both good rheological properties and high crosslinking efficiency.
2Speed
If crosslinking temperature is increased, then crosslinking rate is improved, but damping capacity and plastic range are reduced
Solution Approach 1:
The patent applies parameter changes by implementing a two-stage temperature protocol: Stage 1 at low temperature (≤15°C) preserves damping capacity and plastic range by preventing excessive molecular chain mobility, while Stage 2 at elevated temperature accelerates crosslinking rate. The sequential application of different temperature parameters resolves the contradiction between crosslinking speed and material stability.
3Manufacturing precision
If crosslinking is performed at low temperature, then rheological properties are optimized, but crosslinking time increases
Solution Approach 1:
The patent uses periodic action with two distinct stages: Stage 1 at low temperature (≤15°C) for a controlled duration to establish optimal rheological properties, followed by Stage 2 at elevated temperature to accelerate crosslinking completion. This time-temperature periodic protocol resolves the contradiction by allocating different time periods to different temperature conditions, achieving both optimized rheology and reasonable processing time.
Solution Approach 2:
The patent applies preliminary action by conducting the first crosslinking stage at low temperature before the second stage. This preliminary low-temperature crosslinking establishes the foundation for optimal rheological properties, and the subsequent high-temperature stage completes the crosslinking process more rapidly, reducing overall time loss.
4Strength
If polymer rigidity is increased, then structural stability is improved, but plastic range and deformability are reduced
Solution Approach 1:
The patent applies parameter changes through controlled temperature variation during crosslinking. The low temperature (≤15°C) in Stage 1 limits molecular chain mobility, preventing excessive rigidity development and preserving plastic range. The subsequent temperature increase in Stage 2 enhances crosslinking density for improved rigidity. This dynamic parameter control resolves the contradiction between strength and adaptability.
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 process results in polymers with improved rheological properties, including higher viscous modulus, optimized Tan Δ values, and reduced energy consumption, ensuring better injectability and biocompatibility with minimal polymer modification, suitable for both medical and esthetic applications.
Implementation Method 1
In the context of the present application, 'crosslinking' is understood to mean the creation of covalent bonds between monomers of polymers
Data Source
AI summary
A process for crosslinking a polymer, includes at least the following steps: a) providing a polymer; b) providing a crosslinking agent; c) carrying out one or more crosslinking steps in the presence of the polymer and the crosslinking agent; d) obtaining a crosslinked polymer; wherein the crosslinking step or each of the crosslinking steps is carried out at constant temperature or at a temperature that varies linearly or in a stepwise manner, the constant or variable temperature being less than or equal to 15° C., and in that the crosslinking step c) has a duration of between 3 and 72 hours.