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The study and understanding of the structure and properties of styrene/vinylester (St/VE) and styrene/unsaturated polyester (St/UP) cross-linked thermosets has received technologic and scientific attention, because these resins are widely used as matrices in composites formulations, sharing advantages, such as low room temperature viscosity coupled with good mechanical properties and low cost, plus the added chemical resistance in the case of VE. To investigate the morphologies of these systems, scanning electron microscopy (SEM) offers an useful tool at a micron scale, while the atomic force microscopy (AFM) allows to reach the detail of the topography at a nanometric scale and also to determine the nanostructures of the surface [1]. In both systems, the cross-linked reaction occurs by free radical polymerisation where, big molecular structures are formed through connecting St and UP (or VE) unsaturated comonomers by both interand intra-molecular reactions. These branched structures tend to form a spherical type structure or ‘‘nanogel particle’’, due to the intramolecular cross-linking among the unreacted C = C bonds located in different pendant chains, with reactive radicals [2]. The microgel morphologies are strongly depending of the cure temperature and the initial composition of the reactive mixture as it has been previously reported [2, 3]. In the present work the relationship between the final morphologies and the St-resin initial ratio is analyzed, and the development of the microstructures resulting from the use of the two different unsaturated resins is compared. A natural UP resin was obtained from modified linseed oil in two basic steps: glycerolisis and posterior maleinization [4]. The linseed oil used was provided by Grainer S.A. (Entre Rios, Argentine) and was used without further purification. The glycerol used was 99.5% pure and was obtained from Cientifica Central (Bs. As., Argentine). A commercial soap without additives was used as emulsifier catalyst for this reaction. 2-methyl imidazole was used as catalyst during the maleinization reaction between the glycerol –OH groups and maleic anhydride, both from Fluka A.G Chemical Co. A low molar mass divinylester (VE) monomer was synthesized from the reaction of an epoxy resin diglycidyl ether of bisphenol-A (DGEBA, DER 332 Dow Chemical Co., epoxy equivalent weight 175 g/eq) with methacrylic acid (Norent Plast S.A., laboratory grade reagent), using triphenylphosfine (Fluka A.G., analytical reagent) as catalyst. The final conversion reached was higher than 97% [5]. Different final materials were prepared varying resin:St ratio in a wide concentration range. The high stiffness of these materials allows obtaining fragile fracture surfaces like mirror at room temperature. The general schemes of copolymerization of St/UP and St/VE systems are summarized in Fig. 1. Both synthesis M. A. Mosiewicki (&) AE W. F. Schroeder AE M. I. Aranguren AE J. Borrajo Institute of Material Science and Technology (INTEMA), University of Mar del Plata – National Research, Council. J. B. Justo 4302, 7600 Mar del Plata, Argentina e-mail: jborrajo@fi.mdp.edu.ar

The interaction between poly(o-ethoxyaniline) (POEA) adsorbed onto solid substrates and humic substances (HS) and Cu/sup 2+/ ions has been investigated with UV-VIS spectroscopy and atomic force microscopy. Both HS and Cu/sup 2+/ cause the POEA film to be further doped, and alter the film morphology. This interaction was exploited in a sensor array made of nanostructured films of POEA, sulfonated lignin and HS, which could detect small concentrations of HS and Cu/sup 2+/ in water.