Solvent-sensitive nanospheres prepared by the self-organization of polymerizing hydrophilic graft chain copolymers

Uniform nanospheres were prepared by dispersion copolymerization of n-butyl methacrylate (BMA) with poly(ethylene glycol) (PEG) macromonomers with p-vinylbenzyl end groups in various ethanol/water media. Particle size effects were investigated as a function of macromonomer molecular weight, solvent composition, and initial monomer and initiator concentrations. Hydrodynamic nanoparticle radii (Rh) followed the exponential law of initial initiator, St-PEG macromonomer and BMA concentrations. When reaction conditions were property chosen, nanosphere particle size was controlled from ca. 40 to 750 nm in diameter. It was found that nanospheres swelled in ethanol/water dispersion media and the degree of swelling responded sensitively to solvent composition changes and reached a maximum at ethanol contents of 40-50 vol %.