Determination of site-site distance and site concentration within polymer beads: A combined swelling-electron paramagnetic resonance study

Determination of site-site distance and site concentration within polymer beads: A combined swelling-electron paramagnetic resonance study

Autor Marchetto, R. Google Scholar
Cilli, E. M. Google Scholar
Jubilut, G. N. Google Scholar
Schreier, S. Google Scholar
Nakaie, C. R. Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
UNESP
Universidade de São Paulo (USP)
Resumo [GRAPHICS]This work proposes a combined swelling-electron paramagnetic resonance (EPR) approach aiming at determining some unusual polymer solvation parameters relevant for chemical processes occurring inside beads. Batches of benzhydrylamine-resin (BHAR), a copolymer of styrene-1% divinylbenzene containing phenylmethylamine groups were, labeled with the paramagnetic amino acid 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amine-4-carboxylic acid (TOAC), and their swelling properties and EPR spectra were examined in DCM and DMF. By taking into account the BHARs labeling degrees, the corresponding swelling values, and some polymer structural characteristics, it was possible to calculate polymer swelling parameters, among them, the volume and the number of sites per bead, site-site distances and site concentration. the latter values ranged from 17 to 170 angstrom and from 0.4 to 550 mM, respectively. EPR spectroscopy was applied to validate the multistep calculation strategy of these swelling parameters. Spin-spin interaction was detected in the labeled resins at site-site distances less than approximately 60 A or probe concentrations higher than approximately 1 x 10(-2) M, in close agreement with the values obtained for the spin probe free in solution. Complementarily, the yield of coupling reactions in different resins indicated that the greater the inter-site distance or the lower the site concentration, the faster the reaction. the results suggested that the model and the experimental measurements developed for the determination of solvation parameters represent a relevant step forward for the deeper understanding and improvement of polymer-related processes.
Idioma Inglês
Data de publicação 2005-06-10
Publicado em Journal of Organic Chemistry. Washington: Amer Chemical Soc, v. 70, n. 12, p. 4561-4568, 2005.
ISSN 0022-3263 (Sherpa/Romeo, fator de impacto)
Publicador Amer Chemical Soc
Extensão 4561-4568
Fonte http://dx.doi.org/10.1021/jo0483318
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000229592000001
Endereço permanente http://repositorio.unifesp.br/handle/11600/28342

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