SÃntese e caracterizaÃÃo de surfactantes glicosÃdicos a partir da amilose e alquil fenÃis extraÃdos do LCC. / Synthesis and characterization of glycosidic surfactantes from amylose and alkyl extracted phenols of the LCC.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Nonionic surfactants are synthesised from renewable raw materials such as fat acids and sugars. They are dermatological safe, biodegradable and provide excellent surface active properties, such as good wettability, good foaming production and good cleaning ability. The present work deals with the synthesis and characterization of alkyl polyglycosides where the hydrophilic part is constituted of oligosaccharides derived from the degradation of amylose and the hydrophobic part is constituted from phenolics lipids which constitute the cashew nut shell liquid (CNSL). The condensation reaction between the hydrophilic and hydrophobic parts is the usual KÃenig-Knorr reaction with some modifications. The structural characterization of the surfactants was followed by nuclear magnetic ressonance (NMR) together with Fourier transform IR spectroscopy (FT-IR). The two techniques showed evidence of characteristics bands of aromatic rings, glycosides rings, olefin and paraffin. The cross-peak NOESY spectra demonstrated that the preferred conformation of the glycosidic units in the head groups was of 4C1 type with an anomeric  configuration. The thermal behaviour of the surfactants as well as their behaviour in solution (selfassembly) is strongly dependent of its structural characteristics (head group and hydrophobic tail). Measures of surface tension demonstrated that the Critical Micelle Concentration (CMC) values for the surfactants studied were comparable to the values cited for the nonionic surfactants in the literature. The isothermic study of surface tension versus the concentration natural logarithm indicates that the aggregation behaviour of the alkylphenyl glycosides is dependent of its structural characteristics. The values of the area per molecule âAâ indicate that cardyl glycosides probably form larger aggregates than cardanyl e anacardyl glycosides. Theoretical considerations about the critical packing parameters (CPP) data showed that the major kinds of aggregates are of vesicles and bilayer types indicating the possibility of nanotubes formation by self-assembly once these structures are intermediaries that anticipate the nanostructure formation in solution.

ASSUNTO(S)

lcc amilose sÃntese caracterizaÃÃo lcc quimica inorganica synthesis surfactantes surfactantes amilose characterization

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