We report freeze‐fracture transmission electron microscopy (FFTEM) and scanning electron microscopy (SEM) studies of films prepared by melt‐pressing micrometer‐size polystyrene (PS) and poly(methyl methacrylate) (PMMA) latex samples prepared by surfactant‐free emulsion polymerization. Film samples were prepared in two ways intended to influence the nature of packing in the solid: slow evaporation of water at 40°C and 1 atm, or freezedrying. These powder samples were then gently pressed into transparent films using a Carver press. Samples prepared from freeze‐dried latex are much less ordered then those from slowly dried dispersions. Two kinds of close packing, face‐centered cubic (fcc) and body‐centered cubic (bcc), may exist in different parts of an individual sample. An excellent example of bcc ordering was observed in a sample prepared by slowly drying a PMMA latex dispersion. Under very similar conditions, small regions of both fcc and bcc ordering were observed in PS samples. However, distortion of ideal bcc or fcc packing produces the same pattern of fracture.
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Sosnowski et al. (1994) studied this question.
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