CORE-SHELL LATEX-PARTICLES CONTAINING A FLUORINATED POLYMER IN THE SHELL .2. INTERNAL STRUCTURE STUDIED BY FLUORESCENCE NONRADIATIVE ENERGY-TRANSFER

The internal structure of core-shell latex particles, containing a flu oropolymer in the shell, was determined by the fluorescence nonradiati ve direct energy transfer (NRET) technique. Contrast was achieved by l abeling the core and the shell with fluorescent dyes, a donor and an a cceptor, respectively and inversely. Donor fluorescence emission inten sity was recorded in dilute latex dispersions. Analysis of donor fluor escence decay was carried out by choosing a donor concentration profil e within the particles. The analysis revealed the absence of a sharp b oundary between the core and the shell, but rather a diffuse interface , which was quantified to within a few tens of nanometers for our ca. 230 nm diameter particles. The scale of this interface was changed by varying the compatibility between the core and the shell.