Dielectric spectroscopy of ionic microgel suspensions

摘要: The determination of the net charge and size microgel particles as a function their concentration, well degree association ions to backbone, has been pursued in earlier studies mainly by scattering rheology. These methods suffer from contributions due inter-particle interactions that interfere with characterization single-particle properties. Here we introduce dielectric spectroscopy an alternative experimental method characterize systems. advantage over other is polarization mobile charges within particle only weakly affected interactions. Apart electrode effects, spectra on PNIPAM-co-AA [poly(N-isopropylacrylamide-co-acrylic acid)] ionic suspended de-ionized water exhibit three well-separated relaxation modes, which are particles, diffuse double layer around polymer backbone. Expressions for full frequency dependence electrode-polarization contribution measured response derived, theory proposed resulting microgel. Relaxation modeled realm cell model. found be strongly varying concentration. A very small value diffusion coefficient found, large chemical protons