Functionalized Cellulose Nanocrystals for Nano-Emulsion Stability
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Solution Overview
Problem
Existing methods fail to produce stable emulsions or latexes with nano-sized droplets less than 600 nm in diameter, which are crucial for applications like paints and coatings.
Innovation Solution
The use of hydrophobically functionalized cellulose nanocrystals as surfactants in oil-in-water emulsions, achieved by adding organic, non-water soluble molecules to an aqueous CNC suspension and agitating, allows for the stabilization of emulsions with droplets around 250 nm, and subsequent polymerization of the oil phase to form nano-latexes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If unfunctionalized or lightly charged CNCs are used as stabilizers, then emulsion droplets can be formed, but the droplet size is large (>1 μm) and stability is poor
Solution Approach 1:
The patent applies parameter changes by modifying the surface charge density and hydrophobicity of CNCs through chemical functionalization (sulfonation, carboxymethylation, hydrophobic tail attachment). These parameter changes transform the CNC properties to achieve optimal emulsion stability and nano-scale droplet size control
Solution Approach 2:
The patent creates composite structures by combining hydrophilic CNC cores with hydrophobic functional groups or tail chains. This composite approach allows the CNCs to effectively stabilize oil-in-water emulsions by interacting with both aqueous and organic phases, achieving droplet sizes below 600 nm
2Volume of moving object
If hydrophobic functional groups are added to CNCs to improve emulsion stability, then droplet size decreases to nano-scale, but the complexity of CNC preparation increases
Solution Approach 1:
The patent applies preliminary action by pre-functionalizing CNCs with hydrophobic groups or attaching hydrophobic tail chains before emulsion formation. This preliminary modification ensures that the CNCs are pre-equipped with the necessary amphiphilic properties to achieve nano-scale droplet stabilization without requiring complex post-processing
Solution Approach 2:
The patent systematically varies functionalization parameters (degree of sulfonation, carboxymethylation, hydrophobic chain length) to optimize the balance between emulsion stability and preparation complexity, finding that moderate functionalization levels achieve the best droplet size control
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
This approach enables the creation of environmentally friendly surfactants for coating applications, allowing for controlled nano-sized emulsion droplets and stable latex formation, with droplet sizes less than 300 nm, enhancing the utility of these materials in various industrial applications.
Implementation Method 1
hydrophobically functionalized cellulose nanocrystals, which are used as a surfactant to stabilize the emulsions or latexes
Implementation Method 2
One key attribute of CNCs is their amphiphilic character, which is a consequence of the cellulose crystal structure. They are globally hydrophilic with hydrophobic edges. As such they are known to self-assemble at the oil/water interface.
Implementation Method 3
charged (usually either sulfonate or carboxylic acid functionalized, FIG. 1(d) CNCs are used as they are easier to disperse in water or polar organic solvents (DMF, DMAc, Formic acid, etc.) on account of the electrostatic repulsion introduced by the anionic surface groups.
Implementation Method 4
Stable emulsions are accessed by adding organic, non-water soluble molecules as the oil phase to an aqueous CNC suspension followed by agitation, for example sonication.
Data Source
AI summary
Nano-emulsions and nano-latexes comprising functionalized cellulose nanocrystals (CNCs) as a surfactant that impacts the stability and size of the emulsion droplets of oil-in water emulsions. Stable emulsions can be accessed by adding a desired organic, non-water soluble molecule as the oil phase to an aqueous CNC suspension followed by agitation. Depending on the functionalization of the CNCs, their hydrophilic/hydrophobic balance can be modified, which allows the ability to control the stability and droplet size of the emulsion. Methods for producing nano-emulsions and nano-latexes, when the oil phase contains a polymerizable monomer, are disclosed.