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Type: Artigo de periódico
Title: Heterogeneity In Styrene-butadiene Latex Films.
Author: Santos, Juliane P
Corpart, Pascale
Wong, Kenneth
Galembeck, Fernando
Abstract: Low-Tg styrene-butadiene (SB) latex films were investigated by noncontact atomic force microscopy and scanning electric potential microscopy, revealing a number of different morphologies and electric potential patterns across films cast from the same SB latex dispersions under the same conditions. Surface leveling and charge dispersion throughout the films are, thus, restrained even at temperatures above Tg and the minimum film-formation temperature. An unprecedented electric pattern is observed, in which the particle cores are more positive than the contacting particle outer layers. Different packing patterns, including cubic and hexagonal arrays, coexist in neighboring areas. Zonal centrifugation of the SB latex in sucrose density gradient shows that particles cover a broad range of densities. Thus, film surface heterogeneity is at least partly due to particle heterogeneity. Fractal dimensions of topographic profiles are lower than those of the electric potential profiles, showing that charge mobility is much more restrained than polymer chain motion at the film surface and that it imposes a limit to the charged chain-ends motion.
Subject: Butadienes
Chemistry, Physical
Membranes, Artificial
Microscopy, Atomic Force
Microscopy, Electron, Scanning
Physicochemical Phenomena
Citation: Langmuir : The Acs Journal Of Surfaces And Colloids. v. 20, n. 24, p. 10576-82, 2004-Nov.
Rights: fechado
Identifier DOI: 10.1021/la048319a
Date Issue: 2004
Appears in Collections:Unicamp - Artigos e Outros Documentos

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