Chitosan Oligomer Surfactant for Bitumen Emulsion Stability
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Solution Overview
Problem
Current surfactants used in bituminous and non-bituminous binder emulsions for road construction are often toxic and ecotoxic, posing risks to humans and the environment, and existing biosourced alternatives are not suitable for cationic emulsions, which are commonly used in Europe, or do not provide sufficient adhesion.
Innovation Solution
A bio-based oligomer derived from chitosan is developed by functionalizing chitosan oligomers with fatty alkyl chains, creating a surfactant with free amine functions that can stabilize cationic emulsions and improve adhesion properties, while being non-toxic and environmentally friendly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional surfactants (polyamines, imidazolines, fatty amido-amines) are used in binder emulsions, then emulsification performance is achieved, but toxicity and ecotoxicity increase (GHS05 corrosive/irritant and GHS09 dangerous for the environment)
Solution Approach 1:
The patent changes the chemical composition parameters by using chitosan oligomers with specific molecular weights (500-50,000 g/mol) and degrees of deacetylation (70-100%), functionalized with fatty chains (C12-C22). This parameter optimization maintains emulsification effectiveness while eliminating the toxic effects of conventional surfactants, achieving non-toxic and non-ecotoxic performance.
Solution Approach 2:
The invention creates a composite surfactant structure by combining chitosan oligomers (biopolymer backbone) with grafted fatty chains (hydrophobic groups). This composite structure integrates the biocompatibility and cationic character of chitosan with the surfactant properties of fatty chains, achieving both environmental safety and effective emulsification.
2Object-affected harmful factors
If existing biosourced surfactants are used, then environmental compatibility improves, but suitability for cationic emulsions deteriorates or adhesion performance decreases
Solution Approach 1:
The patent applies local quality by ensuring the chitosan oligomer retains its cationic amino groups (NH3+) at specific locations along the polymer chain, while fatty chains are grafted at other positions. This spatial differentiation allows the molecule to simultaneously provide cationic character for emulsion stability and hydrophobic groups for adhesion, without compromising either function.
Solution Approach 2:
The chitosan-derived surfactant achieves multi-functionality by combining three key properties in one molecule: (1) cationic character from amino groups for emulsion stability, (2) hydrophobic character from fatty chains for adhesion, and (3) biocompatibility from the chitosan backbone. This universal surfactant works for both cationic and nonionic emulsions.
3Object-affected harmful factors
If chitosan is used as emulsifier for cationic bitumen emulsions, then environmental safety improves, but emulsion stability deteriorates over time
Solution Approach 1:
The patent segments the chitosan polymer into oligomers with controlled molecular weights (500-50,000 g/mol, preferably 1,000-10,000 g/mol). This segmentation reduces polymer chain entanglement and improves solubility, preventing phase separation over time while maintaining the cationic character needed for emulsion stability. The oligomeric structure also enhances flexibility in accommodating fatty chain grafts.
Solution Approach 2:
The chitosan oligomers are pre-functionalized with fatty chains before use as surfactants. This preliminary functionalization ensures optimal hydrophobic-hydrophilic balance is achieved beforehand, allowing the surfactant to immediately stabilize the emulsion upon contact with bitumen and water, preventing instability development over time.
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 chitosan-derived surfactant enhances the stability and adhesion of bituminous and non-bituminous binder emulsions, providing effective cationic emulsions with improved chemical and environmental safety, suitable for road applications and civil engineering.
Implementation Method 1
A bio-based oligomer obtained by functionalization of a chitosan oligomer... which can be used in particular as a surfactant with low environmental impact for the manufacture of emulsions of bituminous binders
Implementation Method 2
stabilize cationic emulsions and improve adhesion properties, while being non-toxic and environmentally friendly
Implementation Method 3
This is then at the interface between the oily and aqueous phases. The surfactants currently used are very often amino compounds... A bio-based oligomer obtained by functionalization of a chitosan oligomer so that it comprises monomer units of formula A... where G denotes a fatty alkyl chain... free amine functions
Data Source
AI summary
The invention relates to a bio-based oligomer obtained by functionalizing a chitosan oligomer to comprise monomeric units of formula A or one of their salts, where L denotes a divalent group and G denotes a fatty alkyl chain comprising 5 to 30 carbon atoms, optionally substituted, saturated, or unsaturated. This oligomer can be used as an emulsifier in a cationic or nonionic aqueous emulsion comprising a bituminous or non-bituminous binder.