Core-corona polymer particles for surfactant-free emulsions
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Solution Overview
Problem
Conventional emulsion cosmetics require surfactants for stability, which can cause irritation and unpleasant textures, and existing methods for surfactant-free emulsions, such as Pickering emulsions using inorganic powders, result in unstable and powdery cosmetics.
Innovation Solution
A core-corona polymer particle is developed by radical-polymerizing a polyethylene oxide macromonomer and specific silicone or acrylate derivative monomers under specific conditions, enabling stable oil-in-water and water-in-oil emulsions without surfactants, improving texture and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surfactants are used as emulsifiers in emulsion cosmetics, then emulsion stability is improved, but skin irritation and unpleasant textures (stickiness, sliminess) occur
Solution Approach 1:
The patent uses solid particles (inorganic powders like silica, metal oxides, or organic powders) as intermediary emulsifiers to replace surfactants. These particles adsorb at the oil-water interface and provide steric stabilization, preventing direct contact between oil and water phases without requiring amphiphilic surfactant molecules that cause skin irritation.
Solution Approach 2:
The patent changes the emulsification mechanism from molecular-level surfactant action to particle-level steric stabilization. By controlling particle size (0.1-10 μm), surface properties, and concentration, the patent achieves stable emulsions with different structures (O/W or W/O) without the harmful effects of surfactants.
2Reliability
If inorganic powders are used for Pickering emulsion, then surfactant-free emulsion is achieved, but large amounts of powder are needed resulting in powderiness and squeaky feeling
Solution Approach 1:
The patent optimizes particle size to 0.1-10 μm (preferably 0.5-5 μm), which is small enough to avoid powderiness and squeaky feeling but large enough to provide sufficient steric stabilization. The patent also controls particle concentration to 0.01-5% by mass, balancing emulsion stability with sensory quality.
Solution Approach 2:
The patent uses composite particle structures combining inorganic cores (silica, metal oxides) with organic coatings or surface modifications. This composite structure enhances emulsifying ability per unit mass, reducing the total powder content needed while maintaining stability.
3Ease of manufacture
If inorganic powder is used as emulsifier, then surfactant-free emulsion is achieved, but oil droplets have low stability and are easily unified by stirring or shaking
Solution Approach 1:
The patent creates a protective shell around oil droplets using solid particles that form a physical barrier. This shell provides mechanical protection against coalescence during stirring or shaking, preventing direct contact between oil droplets while maintaining the surfactant-free formulation.
Solution Approach 2:
The solid particles act as intermediary spacers between oil droplets, maintaining separation through steric hindrance. This intermediary layer prevents direct oil-oil contact that would lead to unification, enhancing emulsion stability without requiring surfactants.
4Reliability
If surfactant concentration is elevated in makeup film, then emulsion stability is maintained, but sticky and slimy feeling occurs due to solvent volatilization
Solution Approach 1:
The patent replaces surfactant molecules with solid particle intermediaries that provide steric stabilization. This eliminates the need for high surfactant concentrations in the makeup film, avoiding the sticky and slimy feeling caused by solvent volatilization while maintaining emulsion stability.
Solution Approach 2:
The patent changes the emulsification mechanism from molecular surfactants to particulate emulsifiers, fundamentally altering how the emulsion is stabilized. This parameter change eliminates the concentration-dependent unpleasant textures associated with surfactant-based emulsions.
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 core-corona polymer particle achieves excellent emulsion stability, reduces sticky and powdery feelings, and allows for the creation of both oil-in-water and water-in-oil emulsion cosmetics with enhanced user experience.
Implementation Method 1
a core-corona polymer particle which comprises a core portion and a corona portion extending from the core portion, has a particle size of 10 µm or less, and has a density of 0.85 g/cm³ or less
Implementation Method 2
adsorbing a powder onto the interface between an oil phase and a water phase for emulsification
Implementation Method 3
have a core portion and a corona portion extending from the core portion
Implementation Method 4
has a particle size of 10 µm or less
Data Source
AI summary
Provided are a raw material for a cosmetic and an oil-in-water emulsion cosmetic comprising a core-corona polymer particle excellent in emulsion stability and feeling of use. Certain embodiments of the present invention provides a raw material for a cosmetic, comprising a core-corona polymer particle dispersion obtained by radical-polymerizing a polyethylene oxide macromonomer represented by formula (1) and one or two or more of hydrophobic monomers represented by formulas (2) and (3) under conditions (A) to (D).