Architecture and solution properties of amphiphilic polymer brushes with peripheral charged ions

摘要

Functionalized poly(ethylene oxide) (PEO) macromonomers (alpha-tertiary amino and omega-methacryloyl groups) were prepared by ring-opening polymerization of live PEO anions end-capped with styrene oxide using 2-[2-(N,N-dimethylamino)-ethoxy]ethanol potassium alkoxides as an intiator with methacryloyl chloride. PEO brushes were synthesized by free-radical homopolymerization of such PEO macromonomers. These brushes were converted into peripherallyl charged brushes by quaternization. We studied the solution properties of both types of brushes from the viewpoint of charge effect. It was found form dynamic light scattering (DLS) that the polymer brushes formed a single macromolecule in solution due to crowding of side chains. It was speculated from angular dependence measurements that the polymer brushes with large aspect ratio took a geometrical anisotropic conformation such as a cylinder.. In methanol with a low dielectric constant, radius of gyratin (R_G), and cross-sectional radius of gyration (R_(G,C)) of the polymer brushes with charged side chains were smaller than those of the polymer brushes without charges. In a solvent with a low dielectric constant such as methanol, ionic groups do not dissociate and condense On the other hand, these physical values in an aqueous solution were somewhat larger than those of the polymer brushes without charges. In water with a high dielectric constant, peripherally charged brushes were strongly stabilized by electric double layers.