Investigation of Volume Phase Transition from the Different Properties of Particles

In this work, three different particle sizes: the static radius $R_{s}$, hydrodynamic radius $R_{h}$ and apparent hydrodynamic radius $R_{h,app}$ obtained using the light scattering technique, are investigated for dilute poly-disperse homogenous spherical particles with a simple assumption that the hydrodynamic radius is in proportion to the static radius, when the Rayleigh-Gans-Debye approximation is valid. The results show that the expected values of the normalized time auto-correlation function of the scattered light intensity $g^{(2)}(\tau)$ calculated based on the static particle size information are consistent with the experimental data. The volume phase transition is thus investigated using the equilibrium swelling ratios of static radii and apparent hydrodynamic radii respectively. The changes of the static particle size information and apparent hydrodynamic radius as a function of temperature $T$ show the effects of the volume phase transition on optical properties and the total influences of the volume phase transition on the optical, hydrodynamic characteristics and size distribution of particles, respectively. The effects of cross-linker on the volume phase transition are also discussed.