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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Proton mobility and copper coordination in polysaccharideand gelatin-based bioblends and polyblends

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Author(s):
Mattos, R. I. [1, 2] ; Tambelli, C. E. [1] ; Raphael, E. [2, 3] ; Silva, I. D. A. [4] ; Magon, C. J. [4] ; Donoso, J. P. [4] ; Pawlicka, A. [2]
Total Authors: 7
Affiliation:
[1] Univ Sao Paulo, FZEA, BR-13635900 Pirassununga, SP - Brazil
[2] Univ Sao Paulo, IQSC, BR-13566590 Sao Carlos, SP - Brazil
[3] Univ Fed Sao Joao Del Rei, DCNAT, BR-36301160 Sao Joao Del Rei, MG - Brazil
[4] Univ Sao Paulo, IFSC, BR-13560970 Sao Carlos, SP - Brazil
Total Affiliations: 4
Document type: Journal article
Source: Cellulose; v. 21, n. 4, p. 2247-2259, AUG 2014.
Web of Science Citations: 2
Abstract

Polysaccharide-and gelatin-based bioblends and polyblends were synthesized and characterized by complex impedance spectroscopy, proton nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR). Higher ionic conductivities of 7.9 x 10 (-5) S/ cm at room temperature and 2.5 x 10 (-3) S/ cm at 80 degrees C were obtained for the agarchitosan polyblends. For all samples, the activation energies, calculated from the Arrhenius plot of ionic conductivity and from the onset of NMR line narrowing, are in the range 0.30-0.86 and 0.38-0.57 eV, respectively. The glass transition temperatures (Tg NMR) varied from 200 to 215 K, depending on the sample composition. The temperature dependence of the 1 H spin-lattice relaxation revealed two distinct proton dynamics. The EPR spectra are characteristic of Cu 2 ions in tetragonally distorted octahedral sites. Quantitative analysis of the EPR spin Hamiltonian g|| and A|| parameters revealed copper ions complexed by nitrogens and oxygens in the samples containing chitosan or gelatin and only by oxygens in agar-based ones. The in-plane p bonding is less covalent for the gelatin and chitosan blends. Results suggest that natural bioblends and polyblends are interesting systems to be used in materials science engineering. (AU)

FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
Grantee:Edgar Dutra Zanotto
Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC