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|Type:||Artigo de periódico|
|Title:||Elemental distribution within single latex particles: Determination by electron spectroscopy imaging|
|Abstract:||Particles of a poly[styrene-co-(2-hydroxyethyl methacrylate)] latex were prepared and examined by electron spectroscopy imaging (ESI), using an energy-filtered transmission electron microscope (EFTEM). Both whole particles and thin ultramicrotomed sections were examined, in the brightfield and energy-loss modes. The following elemental distributions were determined, for the larger particles in the latex: (i) C is rather uniformly distributed throughout the raspberry-like latex particles; (ii) O is also distributed throughout the particles but with significant fluctuations from point to point, and it is more concentrated in the vicinity of the particle surfaces; (iii) S distribution resembles that of C, but it is absent from the particle-particle contact areas; (iv) K is mostly found in a thin outer particle layer. Elemental distribution patterns in the smaller particles are different: these have a higher O/C ratio, and K is dispersed in the bulk of the particles. The main conclusions are as follows: hydrophobic and hydrophilic domains are distributed throughout the particles; negative charges are trapped in the particle bulk, and countercations are dispersed in the bulk (small particles) or concentrated at the surfaces (large particles); these results are consistent with particle formation by homogeneous nucleation, following previous work by the Fitch and Okubo groups.|
|Editor:||Amer Chemical Soc|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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