Polymeric Nanoparticles Stabilized by Surfactants: Kinetic Studies

Abstract

A kinetic study was carried out to monitor the time-dependent formation of surfactant-stabilized polymeric nanoparticles prepared by controlled phase separation. The nanoparticles were made of poly(methylmethacrylate) or polystyrene and several ionic and nonionic surfactants. The dispersion was prepared by fast mixing a solution of the polymers in organic solvents with a solution of a surfactant in water. We observed the formation of well-defined nanoparticles measured by time-resolved small-angle x-ray scattering (TR-SAXS). Our results suggest that the kinetics for the formation of nanoparticles comprising ionic surfactants is much faster (in the range of milliseconds) than that for nanoparticles comprising nonionic surfactants (on the time scales of several seconds). We were able to observe the transformation of particle surface from transient structure to hard sphere one in real time. Some systems manifest a plethora of structural changes that demands further experimental research.

Keywords:

• Nanoparticles
• solvent shifting
• time-resolved SAXS

Acknowledgments

The authors acknowledge support by the Grant Agency of the Czech Republic (P208/10/1600).

Notes

^a HLB = Hydrophilic-lipophilic balance.