Polysaccharide Gelled Foam Using CO2-Triggered Ionic Crosslinking
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Solution Overview
Problem
Existing methods for preparing polysaccharide foams, such as alginate foams, require an acid to initiate crosslinking, which can cause pain, irritation, and necessitate costly single-use equipment, complicating in situ applications and affecting mechanical properties.
Innovation Solution
A process involving a solubilized polysaccharide, a divalent ion crosslinking agent in chelated form, and a pH-modifying gas to create a gelled polysaccharide foam without acid, allowing for homogeneous and time-stable foams with good mechanical strength and absorption capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acid is used to initiate crosslinking, then gelation is achieved, but pain and irritation occur
Solution Approach 1:
The patent uses carbon dioxide gas as an intermediary substance to initiate gelation. The CO2 dissolves in the polysaccharide solution to form carbonic acid, which then triggers the crosslinking reaction between calcium ions and carboxylate groups. This intermediary approach allows gelation to occur without direct application of strong acids, thereby eliminating pain and irritation while maintaining reliable gel formation.
Solution Approach 2:
The patent changes the parameter of acid delivery from direct liquid acid application to gaseous CO2 dissolution. By controlling the dissolution of CO2 gas and the resulting carbonic acid formation, the patent achieves gradual and controlled pH change, enabling gelation to proceed without the harsh conditions that cause pain and irritation.
2Reliability
If acid is used to initiate crosslinking, then gelation is achieved, but costly single-use equipment is required
Solution Approach 1:
The patent employs carbon dioxide gas as a safe and controllable intermediary that eliminates the need for expensive acid-resistant equipment. The CO2 can be delivered through simple syringes or gas delivery systems that do not require the specialized single-use equipment needed for handling strong acids, thereby reducing device complexity and cost.
Solution Approach 2:
The patent replaces costly single-use acid delivery systems with inexpensive CO2 delivery mechanisms. Standard syringes or gas cartridges can be used to deliver CO2, eliminating the need for expensive disposable acid-resistant syringes and associated safety equipment.
3Reliability
If acid is used to initiate crosslinking, then gelation is achieved, but mechanical properties are affected
Solution Approach 1:
The patent changes the method of pH control from direct acid addition to CO2 dissolution. This results in more gradual and uniform pH changes throughout the polysaccharide solution, leading to more homogeneous gelation and better mechanical properties. The controlled carbonic acid formation prevents localized over-acidification that would compromise structural integrity.
Solution Approach 2:
Carbon dioxide acts as a gentle intermediary that provides controlled acidification. The CO2 dissolution process naturally limits the acidity level, preventing excessive acid damage to the polysaccharide chains while still achieving sufficient crosslinking for gelation, thereby preserving mechanical strength.
4Stability of the object's composition
If insoluble polyvalent counterions are used, then homogeneous mixing is achieved, but dissolution kinetics must be controlled
Solution Approach 1:
The patent uses carbon dioxide as an intermediary to control the dissolution and activation of calcium ions. The CO2 dissolution process naturally controls the release rate of calcium ions through carbonic acid formation, achieving homogeneous mixing and controlled gelation kinetics without requiring complex external control mechanisms.
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 simplifies the preparation of polysaccharide foams, eliminating the need for acid and single-use equipment, while maintaining mechanical strength and absorption capacity, suitable for biomedical, food, and cosmetic applications.
Implementation Method 1
by incorporating a pH-modifying gas, the pH-modifying gas being an acidic gas, preferably selected from carbon dioxide, sulfur dioxide and/or nitrogen oxide
Implementation Method 2
The soluble salt (from the solubilized polyvalent counter-ion) complexes with the carboxylate groups of the solubilized polysaccharide to form a polysaccharide gel
Implementation Method 3
at least one ionic crosslinking agent for said polysaccharide, said crosslinking agent being a divalent ion in chelated form
Implementation Method 4
by incorporating a pH-modifying gas, the pH-modifying gas being an acidic gas
Data Source
AI summary
The present invention relates to a process for preparing a polysaccharide gelled foam comprising the following steps: a. preparing a mixture comprising: - at least one dissolved polysaccharide chosen from alginates, pectic substances, carrageenans, and mixtures thereof, - at least one solvent of said polysaccharide, - at least one ionic crosslinking agent for crosslinking said polysaccharide, said crosslinking agent being unavailable - optionally a plasticizer soluble in said solvent, - optionally a surfactant, and - optionally an additive, b. foaming and gelling said mixture prepared in step a. by incorporating a pH-modifying gas, and c. optionally drying the gelled foam obtained in step b. The invention also relates to the gelled foam obtained from such a process and also to the uses thereof.