Browsing by Author "Urzua, M"

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    Blends containing Amphiphilic polymers IV. Poly(N-1-alkyl itaconamic acids) with poly(2-vinyl pyridine) and poly(4-vinylphenol)
    (JOHN WILEY & SONS INC, 2002) Urzua, M; Gargallo, L; Radic, D
    The phase behavior of blends containing Poly(N-1-alkyl itaconamic acids) (PNAIA) with Poly(2-vinylpyrindine) (P2VPy) and Poly(4-vinylphenol) (P4VPh) were analyzed by Diferential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR). Miscibility over the whole range of compositions is observed in both systems. All the blends show thermograms exhibiting distinct single glass transition temperatures (T-g), which are intermediate to those of the pure components. The Calorimetric Analysis using Gordon Taylor, Couchman, and Kwei treatments allows conclusion that interactions between the components is favorable to the miscibility. FTIR analysis of the blends suggests that the driving force for miscibility is hydrogen bonding formation. The variation of the absorptions of the carbonyl groups of PNAIA and the hydroxyl groups of P4VPh allows one to attribute the miscibility to weak acid base like interactions. (C) 2002 Wiley Periodicals, Inc.
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    Blends containing amphiphilic polymers. II. Poly(N-1-alkyl itaconamic acids) with poly(4-vinylpyridine) and poly(2-hydroxypropyl methacrylate)
    (MARCEL DEKKER INC, 2000) Urzua, M; Gargallo, L; Radic, D
    The phase behavior of blends containing poly(N-1-alkyl itaconamic acids) (PNAIA) with poly(4-vinylpyridine) (P4VPy) and poly(2-hydroxypropyl methacrylate) (PHPMA) were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. The results are analyzed in terms of the side-chain structure and the specific interactions involved, mainly due to the strong interacting groups present in the different polymers. The behaviors of the blends are discussed in terms of the hydrophobic/hydrophilic ratio and the balance of the different kinds of interactions involved. The strength of the interaction is analyzed in terms of the Gordon-Taylor and Couchman parameters. Miscibility over the whole range of composition for both families of blends is found. The variation of the glass transition T-g with composition together with the FTIR spectra and thermogravimetric profiles show that the blends behave as one-phase material.
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    Modification of the air-water interface by a chitosan adsorption process. Effect on an amphiphilic polymer monolayer
    (WILEY, 2004) Gargallo, L; Leiva, A; Urzua, M; Alegria, L; Miranda, B; Radic, D
    Monolayer formation by poly[(maleic anhydride)-alt-(stearyl methacrylate)] (MA-alt-StM) on aqueous subphases, with and without chitosan, was studied by the Langmuir technique. Chitosan (CS) modified considerably the shape of the MA-alt-StM isotherms on water. To explain this behavior, the surface activity properties of chitosan at the air-solution interface were studied. The variations of the interfacial tension, gamma(int), with chitosan concentration and temperature, were also determined. The results were discussed in terms of the modification of the air-water interface owing to the presence of chitosan in the subphase and the surface activity. It was found that the standard free energy of adsorption, DeltaG(ads)(0),values were dependent on the degree of acetylation (DA) over the DA range being studied. (C) 2004 Society of Chemical Industry.
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    N-1-alkylitaconamic acids-co-styrene copolymers. 1. Synthesis, characterization and monomer reactivity ratios
    (MARCEL DEKKER INC, 2000) Urzua, M; Gatica, N; Gargallo, L; Radic, D
    Copolymers containing N-1-ethylitaconamic acid, N-1-propylitaconamic acid, N-1-butylitaconamic acid, N-1-hexylitaconamic acid, N-1-octylitaconamic acid and N-1-decylitaconamic acid with styrene of different comonomer compositions were synthesized and characterized. Copolymer composition was determined by elemental analysis following the nitrogen content in the resulting copolymers. Monomer reactivity ratios r(1) and r(2) of the different copolymers were estimated using straight line intersection procedures such as Fineman-Ross (F-R) and Kelen-Tudos (K-T) and by a nonlinear one, according to the reactivity ratios error-in-variables model (RREVM). Good agreement between the different procedures for r(1) and r(2) determination was found. Differences in the reactivity of N-1-alkylitaconamic acids (NAIA) relative to styrene were found i.e., ethyl and propyl derivative are less reactive with itself than butyl, hexyl, octyl, and decyl derivatives with itself. Copolymers with some tendency toward small block formation are found.
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    N-1-alkylitaconamic acids-co-styrene copolymers. Surface characterization
    (ELSEVIER SCI LTD, 2003) Miranda, B; Gargallo, L; Urzua, M; Leiva, A; Gonzalez Nilo, F; Radic, D
    A serie of six N-1-alkylitaconamic acids-co-styrene copolymers with alkyl groups varying in side chain length from 3 to 12 was used in this study. The surface behaviour of the copolymers has been studied as function of the side chain length. Contact angle data for two of these copolymer surfaces were obtained in water and several liquids. From this information the surface energy was determined. Differences in the wettability of N-1-alkylitaconamic acid-co-styrene are found. The results are discussed in terms of hydrophobic and polar effect of the copolymers. Results on spread monolayers characteristics of these copolymers on water surfaces are also reported. Surface pressure-area (pi-A) isotherms on a pure water subphase exhibit a transition region depending on the length of the alkyl side chain of the itaconamic acid moiety. It was also analyzed the phase transition in the monolayer at the air/water interface by brewster angle microscopy (BAM). Molecular mechanics approach was used to obtain predictions about the local interaction energies between segments. It was possible to conclude that the local interaction energies of propyl and decyl derivatives are quite similar while the hexyl derivative has higher interaction energy. The analysis of the coulombic energies together with the dispersion van der Waals energies (VDW) would be indicative, in first approximation, that carbonyl groups are more exposed in the case of propyl than in the other copolymers studied. (C) 2003 Elsevier Science Ltd. All rights reserved.