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Nanostructured films comprising a 3-n-propylpyridinium silsesquioxane polymer (designated as SiPy+Cl-) and copper (II) tetrasulfophthalocyanine (CuTsPc) were produced using the Layer-by-Layer technique (LbL). To our knowledge this is the first report on the use of silsesquioxane derivative polymers as building blocks for nanostructured thin films fabrication. Deposition of the multilayers were monitored by UV-Vis spectroscopy revealing the linear increment in the absorbance of the Q-band from CuTsPc at 617 nm with the number of SiPy+Cl-/CuTsPc or CuTsPc/SiPy+Cl-bilayers. FTIR analyses showed that specific interactions between SiPy+Cl- and CuTsPc occurred between SO3- groups of tetrasulfophthalocyanine and the pyridinium groups of the polycation. Morphological studies were carried out using the AFM technique, which showed that the roughness and thickness of the films increase with the number of bilayers. The films displayed electroactivity and were employed to detection of dopamine (DA) and ascorbic acid (AA) using cyclic voltammetry, at concentrations ranging from 1.96 x 10(-4) to 1.31 x 10(-3) molL(-1). The number and the sequence of bilayers deposition influenced the electrochemical response in presence of DA and AA. Using differential pulse technique, films comprising SiPy+/-/CuTsPc were able to distinguish between DA and ascorbic acid (AA), with a potential difference of approximately with 500 mV, in the concentration range of 9.0 x 10(-5) to 2.0 x 10(-4) molL(-1), in pH 3.0.

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AesumoOs compósitos obtidos a partir de fibras de bagaço de cana-de-açúcar e polímeros reciclados (PEAD e PS) foram obtidos através da técnica de extrusão a quente e o planejamento fatorial possibilitou a análise dos fatores que influenciam a obtenção dos compósitos. As amostras contendo polietileno de alta densidade (PEAD), tanto com 30% como com 50% de fibras, mostraram-se mais impermeáveis na presença da água que as amostras obtidas com poliestireno (PS). Os compósitos obtidos com PEAD apresentaram resistência à flexão com uma tensão máxima aplicada de 45 MPa (50% de fibra) e de 39MPa (30% de fibra), esses valores são maiores que os apresentados pelos materiais obtidos com PS. Compósitos de polímeros e madeira (com 60% de serragem) apresenta resistência à flexão de aproximadamente 32 MPa e o MDF apresenta uma resistência à flexão de 36 MPa, esses resultados mostram que os compósitos obtidos possuem uma boa resistência a flexão. Palavras-chaves: compósitos, material reciclável, fibras naturais, técnica de extrusão. AbstractThe composites were obtained through hot extrusion of a mixture of recycled polymers (HDPE and PS) and sugar cane fibers. The extrusion technique resulted in homogeneous materials with good mechanical properties and the factorial design allowed the analysis of the factors that influence the process. Samples containing high density polyethylene (HDPE), both with 30% and 50% fibers were shown to be significantly more effective compared to polystyrene (PS) aiming at impermeability in the presence of water. The composites obtained with HDPE showed bending resistance, with 45 MPa (50% fiber) and 39MPa (30% fiber) maximum applied stress, these values are higher than those presented in the composites obtained with PS. Composites of polymers and wood (60% of sawdust) provide bending resistance of about 32 MPa and MDF has a bending resistance of 36 MPa, these results show that the compounds obtained have a good bending resistance.

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