Interfacial effects in organophilic montmorillonite–poly(ϵ‐caprolactone) nanocomposites

In the last few years much progress has been made in the development of hybrid polymer–inorganic filler nanocomposites. Nevertheless, many questions remain. The comprehension of the structure and the interactions at the polymer–nanofiller interface are crucial to foresee and control the properties of nanocomposites. Because of the high surface ratio of the inorganic nanofiller, the interface is expected to have a prevailing role in determining the nanocomposite properties. In this study we use X‐ray photoelectron spectroscopy (XPS) as a tool for the surface characterization of an organophilic montmorillonite/poly(ε‐caprolactone) exfoliated nanocomposite. The XPS core levels of the nanocomposite have been compared with those obtained from its precursors, and analyzed as reference compounds to evaluate eventual differences attributable to the polymer–nanofiller interfacial interactions. The XPS investigation has allowed us to propose a qualitative model of possible interface interactions between poly(ε‐caprolactone) and the organo‐modified montmorillonite. The model is substantiated by Fourier transform infrared spectroscopy (FTIR). © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3907–3919, 2004     

Palytoxin in seafood by liquid chromatography tandem mass spectrometry: investigation of extraction efficiency and matrix effect

Blooms of Ostreopsis spp. have been recently reported along the Mediterranean coasts of Spain, France, Italy, and Greece posing serious risks to human health. Occurrence of Ostreopsis spp. may result in palytoxin contamination of seafood and, in order to prevent sanitary risks, the need exists to develop efficient extraction procedures to be coupled to rapid and sensitive monitoring methods of palytoxin-like compounds in seafood. In the present study, the best conditions for both extraction of palytoxin from seafood and palytoxin quantification by using liquid chromatography tandem mass spectrometry (LC-MS/MS) were investigated. Three seafood matrices (mussels, sea-urchins, and anchovies) were selected and five different extraction systems were tested, namely: the official protocol for extraction of lipophilic toxins and various aqueous methanol or acetonitrile solutions (MeOH/H₂O 1:1, MeOH/H₂O 8:2, MeCN/H₂O 8:2 and MeOH 100%). Extraction with MeOH/H₂O 8:2 provided the best results in terms of accuracy and matrix interference on LC-MS/MS detection of palytoxin. Accuracy and intra-day reproducibility (n = 3) were evaluated for all the selected matrices but only for mussels at three spiking concentration levels, including the provisional limit proposed by the Community Reference Laboratory for marine biotoxins (250 μg kg⁻¹). Limits of quantitation of palytoxin in mussels, sea-urchins and anchovies tissues were calculated using matrix-matched standards; taking into account extraction efficiency of MeOH/H₂O 8:2, they resulted to be 228, 343, and 500 μg kg⁻¹, respectively.     

Synthesis of new polyazines by 1,4 photochemical or anionic polymerization of 1,2-diaza-1,3-butadienes

Photochemical and anionic polymerizations of 1,2-diaza-1,3-butadienes are described. Photochemical polymerization was smoothly performed by irradiation of some 1-aminocarbonyl-1,2-diaza-1,3-butadienes with high pressure mercury arc (λ = 300 nm) in the presence of allyltributylstannane. Molecular weights (M_w) in the range 14.6-559 × 10² g/mol were obtained. The TGA curve revealed a first weight loss starting at about 200 °C of some 85%, and a second starting at about 300 °C. The DSC showed the glass transition (T_g) at about −34 °C. Anionic polymerization was performed by treatment of some 1-alkoxycarbonyl-1,2-diaza-1,3-butadienes with n-butyllithium. Molecular weights (M_w) in the range 8.44-242 × 10² g/mol were obtained.     

Bifunctional ligands based on the DOTA-monoamide cage

Efficient routes to DOTA-monoamide ligands bearing amino, hydroxyl, aldehyde and maleimido groups are described. These functional groups, which can be spaced at will from the coordination cage, will readily react with suitable groups of targeting moieties. Bioconjugates obtained in this way can be used for diagnostic imaging and therapeutic applications.     

Effect of thermal history on the melting behavior and the crystal-crystal transitions of tetrafluoroethylene-perfluoroalkylvinylether copolymers

By differential scanning calorimetry (DSC), the effect of thermal treatments on the melting of tetrafluoroethylene-perfluoroalkylvinylether copolymers (PFA) with different contents of perfluoromethylvinylether as a comonomer has been investigated. Two melting peaks can be identified for all copolymers, whose presence, value, and extent depend upon the thermal treatments. The higher temperature one, scarcely influenced by the crystallization conditions (i.e., cooling rate and annealing), can be attributed to more perfect crystals present in the original samples. The lower temperature one is produced only by annealing (annealing peak) and can be interpreted as resulting from much poorer crystals grown among the larger ones. For the copolymer with the lowest content of comonomer, the effect of thermal treatments on the low-temperature (crystal-crystal) transitions has also been studied. The rejection of the counits from the crystals, at least in equilibrium conditions, is confirmed. © 1996 John Wiley & Sons, Inc.