Observation of size oscillations in poly(ethylene) glycol/electrolyte composite microparticles

Two-dimensional optical diffraction in polymer/electrolyte composite microparticles has revealed interesting structural/morphological dynamics that occur on a time scale of several minutes. In addition to its utility as a qualitative probe of material homogeneity and phase-separation behavior in composite systems, PEG/NaCl particles probed by optical diffraction exhibit particle size oscillation (up to 100 nanometers peak-to-peak). The specific behavior observed depends on the concentration and nature of the electrolyte in the PEG host particle. These results demonstrate the feasibility of 2-D angular scattering in polymer composite particles as a means for probing structural phase transitions in ultrasmall (10–500 femtoliters) confined volumes.