Molecular Crystals and Liquid Crystals, Vol.374, 159-166, 2002
Particle and polymer microchemistry and electric domain mapping
New microscopy techniques are increasing accessible, yielding hitherto unavailable information on the spatial distribution of chemical constituents in sub-micron and nanosized particles, as well as in polymer films and other materials; this work describes four relevant examples. First, elemental distribution maps of a polystyrene latex obtained by electron spectroscopy coupled to transmission microscopy (ESI-TEM) show that particle C/S ratio is highly variable, evidencing the large differences in polymer Mw's, in different particles. Second, electric potential maps of latex macrocrystals obtained by scanning electron potential microscopy (SEPM) show negative large islands dispersed in a positive continuum, with large electric potential gradients. Backscattered electron imaging (BEI) evidences a core-and-shell structure of silica particles: the particles are made out of smaller domains with variable average atomic number, concentrated at the particle outer layers. The fourth example is a complex columnar structure of electric domains, in crystalline alumina, obtained by SEPM.
Keywords:analytical electron microscopy;scanning electron potential microscopy;elemental mapping;domains;particle heterogeneity;backscattered electron imaging