Cross-linkable Nanocrystalline Xylan via Side Group Removal
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Solution Overview
Problem
Natural xylans are difficult to modify due to steric hindrance from side groups, and alkaline media can cause pH changes, making it challenging to produce stable xylan derivatives with free unsaturated groups for substitution and cross-linking.
Innovation Solution
A method involving the removal of side groups from nanocrystalline xylan to produce unsubstituted xylan with free hydroxy groups, which are then reacted with reactants containing functional groups capable of forming unsaturated bonds, resulting in modified xylan derivatives that can be cross-linked and used as adhesives, thickeners, or in forming hydrogels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If side groups are present on xylan, then the natural structure is maintained, but steric hindrance prevents effective modification of hydroxyl groups
Solution Approach 1:
The patent removes side groups (arabinose, glucuronic acid, acetyl groups) from the xylan structure through chemical treatment with alkaline hydrogen peroxide and enzymatic hydrolysis. This extraction of disturbing side groups eliminates steric hindrance, allowing subsequent modification of hydroxyl groups while maintaining the core xylan backbone structure
Solution Approach 2:
The patent performs preliminary removal of side groups and introduction of saturated groups before the actual modification step. This preliminary action creates a more accessible substrate with reduced steric hindrance, enabling more effective subsequent modification reactions with unsaturated compounds
2Ease of manufacture
If acetyl groups are present on xylan, then the natural structure is maintained, but pH drops during substitution in alkaline media
Solution Approach 1:
The patent removes acetyl groups from the xylan structure through alkaline treatment with hydrogen peroxide. This extraction eliminates the source of pH instability, allowing substitution reactions to proceed in alkaline media without the harmful pH dropping effect that would otherwise occur
Solution Approach 2:
The patent converts the harmful effect of acetyl group degradation (pH drop) into a beneficial process by using controlled alkaline treatment to remove these groups beforehand. The same alkaline conditions that would cause problems during substitution are instead used productively to eliminate the problematic acetyl groups in a controlled manner
3Volume of moving object
If nanocrystalline xylan is used, then particle size is reduced for better applications, but free unsaturated groups must be introduced for cross-linking capability
Solution Approach 1:
The patent performs preliminary introduction of saturated groups (such as methyl or ethyl groups) onto the nanocrystalline xylan before introducing the unsaturated groups. This preliminary saturation step creates intermediate functional groups that facilitate subsequent cross-linking reactions, ensuring the nanocrystalline material has the necessary reactivity for cross-linking while maintaining its small particle size
Solution Approach 2:
The patent changes the chemical parameters of the xylan by introducing unsaturated groups (such as vinyl or allyl groups) through chemical modification. This parameter change transforms the chemical reactivity of the nanocrystalline xylan, enabling cross-linking capability while preserving the beneficial small particle size for various applications
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 method allows for the production of stable xylan derivatives with controlled substitution, enabling their use as effective adhesives, thickeners, and in forming transparent hydrogels or polymer films, with adjustable lower-critical-solution-temperature properties.
Implementation Method 1
reacting the unsubstituted xylan with a reactant, which has a first functional group capable of reacting with the free hydroxy groups and a second functional group comprising free double bonds, to produce modified xylan
Data Source
AI summary
The present invention relates to nanocrystalline xylan containing at least 0.1 free unsaturated groups per anhydroxylose unit, wherein free unsaturated groups are groups which exhibit unsaturated bonds, and which are capable of reacting with other groups, and the particle size of the xylan crystals is about 10 to 250 nm.