Water-swellable polyelectrolyte microgels polymerized in an inverse microemulsion using a nonionic surfactant

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Development of novel polymerization techniques for advanced materials.
• Understanding the relationship between polymer structure and solution properties.
• Investigating the synthesis of functional microgels for various applications.

Purpose of the Study:

• To synthesize poly(dimethylacrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid) microgels using inverse microemulsion polymerization (IMEP).
• To characterize the viscometric properties of the synthesized microgels.
• To investigate the thickening behavior of the microgel solutions.

Main Methods:

• Inverse microemulsion polymerization (IMEP) in a pseudoternary system (n-hexane, nonionic surfactant C18En, aqueous monomer solution).
• Phase diagram determination for IMEP system optimization.
• Transmission electron microscopy (TEM) for microgel size analysis.
• Viscometry to determine intrinsic viscosity and overlap concentration (c*).
• Rheological measurements to assess apparent yield stress.

Main Results:

• Successful polymerization of poly(dimethylacrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid) microgels within 50 nm reversed micelles.
• Intrinsic viscosity values of 25 dl/g for noncrosslinked and 7.4 dl/g for crosslinked (0.1 mol% MBA) polymers.
• Significant thickening effect observed in crosslinked microgel solutions above c* (c[eta] = 1), attributed to interparticle friction.

Conclusions:

• The IMEP system is effective for synthesizing functional microgels with controlled size.
• Crosslinked microgels demonstrate substantial thickening behavior at higher concentrations.
• The findings suggest potential applications for these microgels in areas requiring viscosity modification.