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[Gel-emulsion systems. I. Physical-chemical characterisation]
Mária Szucs1, Szabolcs Budai, István Eros
1Szegedi Tudományegyetem Gyógyszer-technológiai Intézet, Szeged, Eötvös u. 6. - 6720.
Acta Pharmaceutica Hungarica
|May 15, 2008
Summary
Polymeric surfactants form microgel structures that stabilize oil-in-water emulsion gels. Increased polymer and oil concentrations enhance viscoelastic properties and viscosity, while higher polymer concentrations reduce droplet size.
Area of Science:
- Materials Science
- Colloid and Surface Chemistry
Background:
- Emulsion gels are complex fluids with applications in various industries.
- Stabilization mechanisms in emulsion gels are crucial for their performance.
- Polymeric surfactants offer unique properties for emulsion stabilization.
Purpose of the Study:
- To investigate the structure and properties of emulsion gels stabilized by polyacrylic acid-alkyl acrylate diblock copolymer surfactants.
- To verify the proposed microgel structure stabilizing the emulsions.
- To analyze the effects of polymer concentration and oil content on rheological properties, water evaporation, and droplet size.
Main Methods:
- Preparation of emulsion gels using diblock copolymer surfactants.
- Thermoanalytic investigation to verify microgel structure.
- Rheological measurements to assess viscoelastic properties.
- Analysis of water evaporation rates and droplet size distribution.
Main Results:
- Thermoanalysis confirmed the formation of a microgel structure around oil droplets, providing steric stabilization.
- Emulsion gels exhibited viscoelastic properties.
- Viscosity increased exponentially with both polymer concentration and oil content.
- Water was present in two distinct forms: within the microgel and in the dispersion medium.
- Droplet size distribution was predominantly monodisperse.
- Average droplet size decreased as polymer concentration increased.
Conclusions:
- Polyacrylic acid-alkyl acrylate diblock copolymers effectively stabilize emulsion gels via a microgel structure.
- The rheological behavior is highly dependent on polymer and oil concentrations.
- The stabilization mechanism involves steric hindrance provided by the polymer microgel.
- Control over polymer concentration allows tuning of droplet size and emulsion properties.
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