Structure of polymeric nanoparticles in surfactant-stabilized aqueous dispersions of high-molar-mass hydrophobic graft copolymers

Aqueous dispersions of hydrophobic high-molar-mass cellulose-graft-polystyrene (Cel-g-PS) copolymers were prepared by nanoprecipitation from 1,4-dioxane solutions using sodium dodecyl sulfate as a stabilizer. The size and structure of formed Cel-g-PS nanoparticles were studied by scattering techniques (static and dynamic light scattering, SAXS) and transmission electron microscopy. The scattering and microscopy data show that nanoprecipitation of Cel-g-PS leads to the formation of polydisperse aggregates of collapsed Cel-g-PS macromolecules containing entrapped SDS micelles in the kinetically frozen state. The final size of the aggregates can be tuned by changing the copolymer concentration, cP, in the dioxane solution. The average hydrodynamic radius of the aggregates, RH, scales as [(RH/RH,0)2.5 – 1] ∼ cP, where RH,0 is the RH value extrapolated to the zero copolymer concentration.