A sulfonação homogênea do poliestireno foi desenvolvida em escala pré-piloto produzindo polímeros com diferentes graus de sulfonação (18 a 22 mol % de unidades estirênicas sulfonadas). O rendimento da reação depende principalmente da razão entre a concentração de sulfato de acetila e de poliestireno. As propriedades morfológicas e térmicas dos poliestirenos sulfonados, obtidas pela sulfonação homogênea, foram estudadas por microscopia eletrônica de varredura, calorimetria diferencial de varredura e termogravimetria. A temperatura de transição vítrea do poliestireno sulfonado aumenta em relação ao poliestireno puro e a ∆Cp foi calculada a fim de confirmar as fortes interações com os grupos ~SO 3 H.The homogenous sulfonation of polystyrene was developed in a pilot plant scale producing polymers with different sulfonation degrees (18 to 22 mole % of sulfonated styrene units). The reaction yield depends chiefly on the concentration ratio of acetyl sulfate and polystyrene. The morphological and thermal properties of the sulfonated polystyrene obtained by homogeneous sulfonation were studied by means of scanning electron microscopy, differential scanning calorimetry and thermogravimetry. The glass transition temperature of sulfonated polystyrene increases in relation to pure polystyrene and ∆Cp was evaluated in order to confirm the strong interactions among thẽ SO 3 H groups.

THE TECHNOLOGY OF POLYMER RECYCLING. Solid municipal waste contains a large volume of polymers and its final disposal is a serious environmental problem. Consequently, the recycling of the principal polymers present in the solid waste is an alternative. In this review we describe the mechanical and chemical recycling of polymers and the energy recovery from plastic wastes. Polymer recycling involves not only the development of processing technologies, but also the solution of many chemical and analytical problems. The technological, economical and social aspects of polymer recycling are also considered.

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All‐plastic and flexible electrochromic devices will facilitate new technological applications, such as information display and storage, in the automotive industry (rear‐view mirrors) and in architecture (smart windows). Here the authors describe an all‐plastic and flexible solid‐state electrochromic device using two optically complementary conductive polymer blends deposited on ITO‐PET (indium tin oxide–poly(ethyleneterephthalate)), and a polymeric electrolyte. The device was constructed under atmospheric conditions and showed good optical characteristics.

Animals rely on olfaction to navigate through complex olfactory landscapes, but the mechanisms that allow an animal to encode the spatial structure of an odorous environment remain unclear. To acquire information about the spatial distribution of an odorant, animals may rely on bilateral olfactory organs and compare side differences of odor intensity and timing [1-6] or may perform spatial and temporal signal integration of subsequent samplings [7]. The American cockroach can efficiently locate a source of sex pheromone even after the removal of one antenna, suggesting that bilateral comparison is not a prerequisite for odor localization in this species [8, 9]. Cognate olfactory sensory neurons (OSNs) originating from different locations on the flagellum, but bearing the same olfactory receptor, converge onto the same glomerulus within the antennal lobe, which is thought to result in a loss of spatial information. Here, we identified 12 types of pheromone-responsive projection neurons (PNs), each with spatially tuned receptive field. The combination of (1) the antennotopic organization of OSNs terminals and (2) the stereotyped compartmentalization of PNs' dendritic arborization within the macroglomerulus (MG), allows encoding the spatial position of the pheromone. Furthermore, each PN type innervates a different compartment of the mushroom body, providing the means for encoding spatial olfactory information along the olfactory circuit. Finally, MG PNs exhibit both excitatory and inhibitory spatial receptive fields and modulate their responses based on changes in stimulus geometry. In conclusion, we propose a mechanism for encoding information on the spatial distribution of a pheromone, expanding both our understanding of odor coding and of the strategies insects adopt to localize a sexual mate.