Raspberry-shaped composite microgel synthesis by seeded emulsion polymerization with hydrogel particles.
Daisuke Suzuki1, Chiaki Kobayashi
1Graduate School of Textile Science & Technology, Shinshu University , 3-15-1 Tokida, Ueda 386-8567, Japan.
Langmuir : the ACS Journal of Surfaces and Colloids
|June 3, 2014
Summary
Researchers created raspberry-shaped composite microgels using seeded emulsion polymerization. Thermoresponsive poly(N-isopropylacrylamide) cores enabled tunable polystyrene particle growth, influencing deswelling behavior.
Area of Science:
- Polymer Science
- Materials Science
- Nanotechnology
Background:
- Thermoresponsive hydrogels, specifically poly(N-isopropylacrylamide) (PNIPAM), are sensitive to temperature changes.
- Seeded emulsion polymerization allows for the controlled growth of polymer particles onto existing microgel cores.
- Composite microgels combine properties of different materials for advanced applications.
Purpose of the Study:
- To synthesize raspberry-shaped composite microgels via seeded emulsion polymerization.
- To investigate the effect of styrene concentration and surfactant (sodium dodecyl sulfate - SDS) on composite microgel morphology and thermoresponsive behavior.
- To elucidate the mechanism of seeded emulsion polymerization with thermoresponsive microgel cores.
Main Methods:
- Seeded emulsion polymerization of styrene using thermoresponsive PNIPAM microgels as cores.
- Varying styrene concentration and SDS concentration during polymerization.
- Characterization of composite microgels' structure and thermoresponsive properties (deswelling behavior).
Main Results:
- Raspberry-shaped composite microgels were successfully synthesized.
- Increased styrene concentration led to larger polystyrene particles on the core microgels.
- Surfactant (SDS) concentration critically affected thermoresponsive behavior; high SDS levels (above 6.5 mM) inhibited deswelling by covering the core microgels.
- Polystyrene particles could form both on the surface and within the core microgels above a critical SDS concentration.
Conclusions:
- The synthesis method allows for the creation of tunable composite microgels with distinct morphologies.
- The thermoresponsive behavior of the composite microgels is highly dependent on the presence and concentration of surfactant during polymerization.
- A mechanism for seeded emulsion polymerization involving thermoresponsive microgel cores and water-immiscible monomers was proposed, highlighting the role of core swelling and surfactant interactions.
