Browsing by Author "Gatica, N"

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    Blends of poly(hydroxypropyl methacrylate) with 4-vinyl-co-N-vinyl-2-pyrrolidone and with vinyltrimethylsilane-co-N-vinyl-2-pyrrolidone copolymers.: The effect of copolymer composition on interpolymer compatibility
    (2001) Radic, D; Gatica, N; Gargallo, L
    Glass transition temperatures (Figs. 1, 3), DSC and TGA thermograms (Figs. 2, 4), and Fourier transform infrared (FTIR) spectra (Fig. 5) showed the binary blends (Table 1) of poly(2-hydroxypropyl methacrylate) (PHPMA) with 4-vinylpyridine-co-N-vinyl-2-pyrrolidone (4-VPy-co-VP) to be compatible over the whole range of compositions. The blends of PHPMA with vinyltrimethylsilane-co-N-vinyl-2-pyrrolidone (VTMS-co-VP) were found to be compatible up to VTMS contents of similar to 25 wt. %. The former blends (Figs. 1, 2) are believed to be compatible on account of H-bonding of PHPMA's OH with the 4VPy and VP units of 4VPy-co-VP. In the latter blends, up to 25.7% of VTMS, H-bonds between PHPMA's OH groups and VP units suffice to provide compatibility, but at > 25.7 wt. % VTMS, hydrophobic interactions of the VTMS moieties prevail and phase separation occurs.
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    Monomer reactivity in functionalized vinyl copolymers: A theoretical approach
    (MARCEL DEKKER INC, 2004) Gatica, N; Gargallo, L; Radic, D
    This work studies how the variation of the inter-atomic distance affects the total energy in addition reactions of several vinyl radicals on vinyl monomers. Based on the energetic profiles obtained, the corresponding activation eneigies were evaluated and correlated with the relative reactivity of the monomers forming the vinyl copolymers poly(2-vinylpyridine-co-N-vinyl-2-pyrrolidone), poly(4-vinylpyridine-co-N-vinyl-2-pyrrolidone), poly(vinyltrimethylsilane-co-N-vinyl-2-pyrrolidone) and poly(vinylcyclohexane-co-N-vinyl-2-pyrrolidone), previously characterized with an estimation of their monomer reactivity ratios (MRR). The results are discussed as a theoretical support to a work developed in the general framework of the synthesis and characterization of functionalized vinyl copolymers.
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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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    Synthesis and characterization of functionalized vinyl copolymers -: II.: Structure-monomer reactivity relationship in copolymers containing 4-vinylpyridine moieties
    (2006) Gatica, N; Fernández, N; Opazo, A; Radic, D
    Copolymers containing 4-vinylpyridine as common monomer with tert-butyl acrylate and acrylic acid of different comonomer compositions were synthesized and characterized. Copolymer composition was determined by elemental analysis, from which monomer reactivity ratios (MRR, r) were estimated using straight line intersection procedures such as Fineman-Ross and Kelen-Tudos methods and a nonlinear one, the Reactivity Ratios Error in Variables Model. In this case, the values of MRR are r(4VPy) = 0.046 and r(tBA) = 0.054 (for 4VPy-co-tBA), and r(4VPy) = 0.0 and r(AA) = 0.610 (for 4VPy-co-AA). A copolymer tending to the alternation and another containing isolated units of one of the monomers between small blocks of the another one were obtained, depending on the chemical nature of the comonomers. The different proposed comonomer distributions are analyzed in terms of the obtained MRR values and compared with related systems. The MRR are connected with structural properties of the monomers such as polarity, aromaticity and electron delocalization.
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    Synthesis and characterization of functionalized vinyl copolymers I. Structure-monomer reactivity relationship in copolymers containing N-vinyl-2-pyrrolidone moieties
    (SOC CHILENA QUIMICA, 2005) Gatica, N; Fernandez, N; Opazo, A; Radic, D
    Copolymers containing N-vinyl-2-pyrrolidone as a common monomer with acrylic acid, 4-methyl styrene and vinyltrichlorosilane of different comonomer compositions were synthesized and characterized. Copolymer composition was determined by elemental analysis, from which monomer reactivity ratios (MRR, r) were estimated using straight line intersection procedures, such as Fineman-Ross and Kelen-Tudos methods, and a nonlinear one, the Reactivity Ratios Error in Variables Model. In this case, the values of MRR are r(VP) = 0.1 and r(AA) = 1.1 (for VP-co-AA), r(VP) = 0.8 and r(4MS) = 14.6 (for VP-co-4MS), and r(VP) = 0.0 and r(VTCS) = 0.3 (for VP-co-VTCS).
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    Synthesis and characterization of functionalized vinyl copolymers.: Electronegativity and comonomer reactivity in radical copolymerization
    (2003) Gatica, N; Fernández, N; Opazo, A; Alegría, S; Gargallo, L; Radic, D
    Vinylsilane monomers (vinyltrimethoxysilane (VTMOS) and vinyltriethoxysilane (VTEOS)), methyl methacrylate (MMA), tert-butyl acrylate (tBA) and N-vinyl-2-pyrrolidone (VP) were used in the synthesis of functionalized vinyl copolymers. By using these monomers, VTMOS-co-MMA, tBA-co-VP and VTEOS-co-VP, with various compositions, were synthesized. The copolymers were characterized by viscometry, H-1-NMR, FTIR and elemental analysis. The monomer reactivity ratios were estimated by the Fineman-Ross and Kelen-Tudos linear procedures. These parameters were also estimated by using a computer program based on a non-linear minimization procedure known as Reactivity Ratios Error in Variables Model. Random copolymers and others containing blocks of one of the monomer units were obtained, depending on the chemical nature of the comonomers. The estimated comonomer sequence and distribution are discussed in terms of structural properties of the monomers such as molecular volume of the side groups, electronegativity of the substituents and steric hindrance. Analysis by comparison with other copolymers with analogous structures was also performed. (C) 2003 Society of Chemical Industry.
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    Synthesis and monomer reactivity ratios of (vinyleyclohexane-co-N-vinyl-2-pyrrolidone) copolymer
    (2002) Gatica, N; Gargallo, L; Radic, D
    A copolymer containing vinylcyclohexane (VCH) and N-vinyl-2-pyrrolidone (VP) at different compositions was synthesized and characterized. The monomer reactivity ratios (MRR) were estimated by using the classical Fineman-Ross and Kelen-Tudos linear fitting methods. These parameters were also estimated using a nonlinear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). In this case, the values of MRR are r(VP) = 2.2 and r(VCH) = 0,0. Composition shifts and MRR values for (vinylcyclohexane-co-N-vinyl-2-pyrrolidone) copolymer (VCH-co-VP) are interpreted in terms of the relative comonomeric structures. A copolymer with zones containing VP blocks with isolated units of VCH between them is obtained. The presence or absence of the resonance stabilization effect is taken into account. The results are compared with those of similar related copolymeric systems. (C) 2002 Elsevier Science Ltd. All rights reserved.
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    Vinyltrimethoxysilane-co-2-vinylpyridine copolymer -: Synthesis and monomer reactivity ratios
    (1999) Gatica, N; Gargallo, L; Radic, D
    Copolymers containing vinyltrimethoxysilane (VTMOS) and 2-vinylpyridine (2VPy) at different compositions were synthesized and characterized. The monomer reactivity ratios r(1) and r(2) were estimated by using the classical Fineman-Ross and Kelen Tudos linear fitting procedures. Moreover, these parameters were also estimated using a nonlinear computational fitting known as Reactivity Ratios Error in Variable Method (RREVM). Attempts to obtain the corresponding copolymer with vinyltrimethylsilane (VTMS) were performed but only hompolymerization 2VPy is observed due to the non-reactivity of VTMS under this conditions. The results were analysed in terms of the relative comonomeric structures and compared with similar related systems. The reactivities are interpreted in terms of the resonance and stabilization effects together with the chemical structure.
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    Vinyltrimethylsilane-co-methylmethacrylate copolymers. Synthesis and reactivity ratios
    (MARCEL DEKKER INC, 2000) Gatica, N; Alegria, S; Tagle, LH; Diaz, F; Gargallo, L; Radic, D
    In order to obtain information about the copolymerization process of vinyltrimethyl silane with comonomers of different chemical structure, copolymers containing vinyltrimethylsilane and methyl methacrylate at different compositions were synthesized and characterized. Comparison of the reactivity ratios of the resulting copolymers with those containing N-vinyl-2-pyrrolidone and 2-vinylpyridine previously reported and other related comonomers with different chemical structure allows us to establish some reactivity structure relationship and a generalization for these systems. The monomer reactivity ratios r(1) and r(2) (MRR) were estimated by using the classical linear fitting procedures and also through a computer program based on a nonlinear minimization algorithm, starting from the r(1) and r(2) values obtained by the former procedures.
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    Vinyltrimethylsilane-co-N-vinyl-2-pyrroline and vinyltrimethoxysilane-co-N-vinyl-2-pyrrolidone copolymers - Synthesis and reactivity ratios
    (1998) Gatica, N; Diaz, FR; Gargallo, L; Radic, D
    Copolymers containing vinyltrimethylsilane and vinyltrimethoxysilane with N-vinyl-2-pyrrolidone at different compositions were synthesized and characterized. The reactivity ratios was estimated by using the classical Fineman-Ross and Kelen Tudos linear fitting procedures. These parameters were also estimated through a computer program based on nonlinear minimization algorithm, starting from the r(1) and r(2) values obtained by the former procedures. The analysis of the results allow us to interpret the reactivity behaviour of these polymers in terms of the relative reactivity of the substiuents. The effect of the chemical structure of the polymer side group is discussed in terms of the different contributions to the stabilization of the radical intermediates.