Browsing by Author "Gatica, N"

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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 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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    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.