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

Two-dimensional optical diffraction in polymer/electrolyte composite microp articles has revealed interesting structural/morphological dynamics that oc cur on a time scale of several minutes. In addition to its utility as a qua litative probe of material homogeneity and phase-separation behavior in com posite systems, PEG/NaCl particles probed by optical diffraction exhibit pa rticle size oscillation (up to 100 nanometers peak-to-peak). The specific b ehavior 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 s tructural phase transitions in ultrasmall (10-500 femtoliters) confined vol umes. (C) 2000 Elsevier Science B.V. All rights reserved.