Correlation between Electrical Properties and Potentiometric Response of CS-Clay Nanocomposite Membranes

The aim of this work is to study the relationship between electrical, structure, and potentiometric response to nitrate anions using Ion Selective Electrodes (ISE). These ISE are based on chitosan-montmorillonite nanocomposite membranes with different content of montmorillonite. Membrane properties have been studied using SEM, FTIR, and impedance spectroscopy measurements. With the advent of impedance spectroscopy one is allowed to obtain the DC conductivity dependence on montmorillonite concentration and the percolation threshold. Additionally, the potentiometric response to nitrate anions of ISE based on chitosan-clay nanocomposite has been investigated. It is shown that the properties and performance of these membrane electrodes depend upon the clay wt% and that the best sensitivity to nitrate ions (with detection limit 7 × 10−5 M) is obtained near the percolation concentration ca. 8 ± 2.5 wt% of clay. This observation is traceable to higher clay content (higher agglomeration) that tends to decrease the intercalation and absorption of the number of chitosan chains in the interlayer space of montmorillonite

Selected heavy metals and selenium in the blood of black sea turtle (Chelonia mydas agasiizzi) from Sonora, Mexico

A new series of segmented copolymers were synthesized from poly(ethylene terephthalate) (PET) oligomers and polyethylene glycol) (PEG) by a two-step solution polymerization reaction. PET oligomers were obtained by glycolysis depolymerization. Structural features were denned by infrared and nuclear magnetic resonance (NMR) spectroscopy. The copolymer composition was calculated via 1H NMR spectroscopy. The content of soft PEG segments was higher than that of hard PET segments. A single glass-transition temperature was detected for all the synthesized segmented copolymers. This observation was found to be independent of the initial PET-to-PEG molar ratio. The molar masses of the copolymers were determined by gel permeation chromatographv (GPC). "2004 Wiley Periodicals, Inc.",,,,,,"10.1002/pola.20301",,,"http://hdl.handle.net/20.500.12104/44425","http://www.scopus.com/inward/record.url?eid=2-s2.0-4444338219&partnerID=40&md5=d2eb00aebe928925be80030b03260011",,,,,,"17",,"Journal of Polymer Science, Part A: Polymer Chemistry",,"444

Segmented block copolymers of poly(ethylene glycol) and poly(ethylene terephthalate)

A new series of segmented copolymers were synthesized from poly(ethylene terephthalate) (PET) oligomers and polyethylene glycol) (PEG) by a two-step solution polymerization reaction. PET oligomers were obtained by glycolysis depolymerization. Structural features were denned by infrared and nuclear magnetic resonance (NMR) spectroscopy. The copolymer composition was calculated via 1H NMR spectroscopy. The content of soft PEG segments was higher than that of hard PET segments. A single glass-transition temperature was detected for all the synthesized segmented copolymers. This observation was found to be independent of the initial PET-to-PEG molar ratio. The molar masses of the copolymers were determined by gel permeation chromatographv (GPC). ©2004 Wiley Periodicals, Inc

Post-consumer HDPE/AGAVE fibre composites coated with chitosan used for removal of heavy metals

Composites of post-consumer high density polyethylene (HDPE) with agave fibre were prepared by extrusion and coated with chitosan. A chemical pre-treatment was applied to the composite to enhance chitosan gel compatibility. The adsorption capacity of the composite coated with chitosan was evaluated for Cd(II) and Cu(II). The coated composites were characterized by SEM, ATR-IR and XPS. Atomic Absorption Spectroscopy (AA) was used to measure metal uptake in batch studies. Adsorption Isotherms were obtained at three different pH values. The results of this study demonstrate the composite's ability to immobilize chitosan on its surface and its capacity to adsorb metal ions

Post-consumer HDPE/AGAVE fibre composites coated with chitosan used for removal of heavy metals

Composites of post-consumer high density polyethylene (HDPE) with agave fibre were prepared by extrusion and coated with chitosan. A chemical pre-treatment was applied to the composite to enhance chitosan gel compatibility. The adsorption capacity of the composite coated with chitosan was evaluated for Cd(II) and Cu(II). The coated composites were characterized by SEM, ATR-IR and XPS. Atomic Absorption Spectroscopy (AA) was used to measure metal uptake in batch studies. Adsorption Isotherms were obtained at three different pH values. The results of this study demonstrate the composite's ability to immobilize chitosan on its surface and its capacity to adsorb metal ions

Porous monoliths synthesized via polymerization of styrene and divinyl benzene in nonaqueous deep-eutectic solvent-based HIPEs

CONACYT [181678]; Catedras CONACYT programs; CONACYT through Estancias postdoctorales en el extranjero; [MAT2012-34811

Miscibility behavior and hydrogen bonding in blends of poly(vinyl phenyl ketone hydrogenated) and poly(2-ethyl-2-oxazoline)

The miscibility behavior of poly(2-ethyl-2-oxazoline) (PEOx)/poly(vinyl phenyl ketone hydrogenated) (PVPhKH) blends was studied for the entire range of compositions. Differential scanning calorimetry and thermomechanical analysis measurements showed that all the PEOx/PVPhKH blends studied had a single glass-transition temperature (Tg). The natural tendency of PVPhKH to self-associate through hydrogen bonding was modified by the presence of PEOx. Partial IR spectra of these blends suggested that amide groups in PEOx and hydroxyl groups in PVPhKH interacted through hydrogen bonding. This physical interaction had a positive influence on the phase behavior of PEOx/PVPhKH blends. The Kwei equation for Tg as a function of the blend composition was satisfactorily used to describe the experimental data. Pure-component pressure-volume-temperature data were also reported for both PEOx and PVPhKH. � 2004 Wiley Periodicals, Inc

Synthesis and characterization of a poly(ether-ester) copolymer from poly(2,6 dimethyl-1,4-phenylene oxide) and poly(ethylene terephthalate)

A series of poly (ether-ester) copolymers were synthesized from poly(2,6 dimethyl-1,4-phenylene oxide) (PPO) and polyethylene terephthalate) (PET). The synthesis was carried out by two-step solution polymerization process. PET oligomers were synthesized via glycolysis and subsequently used in the copolymerization reaction. FTIR spectroscopy analysis shows the coexistence of spectral contributions of PPO and PET on the spectra of their ether-ester copolymers. The composition of the poly (ether-ester)s was calculated via 1H NMR spectroscopy. A single glass transi tion temperature was detected for all synthesized poly(ether-ester)s. Tg behavior as a function of poly(ether-ester) composition is well represented by the Gordon-Taylor equation. The molar masses of the copolymers synthesized were calculated by viscosimetry. © 2005 Wiley Periodicals, Inc