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Molecular Dynamics of Poly(Ethylene Glycol) Intercalated in Clay, Studied Using 13C Solid-State NMR
São Carlos Institute of Physics, University of São Paulo, P.O.Box 369, São Carlos, SP 13560-970, Brazil
Current address: Technological Science Center, UENF, Campos dos Goytacazes, RJ 28013-602, Brazil.
Current address: Center of Engineering Modeling and Applied Social Sciences, CECS, Federal University of ABC, Bairro Bangu, Santo André, SP 09210-170, Brazil.
* Authors to whom correspondence should be addressed.
Received: 29 October 2012; in revised form: 3 December 2012 / Accepted: 5 December 2012 / Published: 21 December 2012
Abstract: In this study, Cross-Polarization Magic-angle Spinning CP/MAS, 2D Exchange, Centerband-Only Detection of Exchange (CODEX), and Separated-Local-Field (SLF) NMR experiments were used to study the molecular dynamics of poly(ethylene glycol) (PEG) inside Hectorite/PEG intercalation compounds in both single- and double-layer configurations. The results revealed that the overall amplitude of the motions of the PEG chain in the single-layer configuration is considerably smaller than that observed for the double-layer intercalation compound. This result indicates that the effect of having the polymer chain interacting with both clay platelets is to produce a substantial decrease in the motional amplitudes of those chains. The presence of these dynamically restricted segments might be explained by the presence of anchoring points between the clay platelets and the PEG oxygen atoms, which was induced by the Na+ cations. By comparing the PEG motional amplitudes of the double-layered nanocomposites composed of polymers with different molecular weights, a decrease in the motional amplitude for the smaller PEG chain was observed, which might also be understood using the presence of anchoring points.
Keywords: molecular dynamics; polymer intercalation; layered silicates; smectite clays; polymer electrolytes; Exchange NMR; nanocomposites
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Franco, R.W.A.; Brasil, C.A.; Mantovani, G.L.; Azevedo, E.R.; Bonagamba, T.J. Molecular Dynamics of Poly(Ethylene Glycol) Intercalated in Clay, Studied Using 13C Solid-State NMR. Materials 2013, 6, 47-64.
Franco RWA, Brasil CA, Mantovani GL, Azevedo ER, Bonagamba TJ. Molecular Dynamics of Poly(Ethylene Glycol) Intercalated in Clay, Studied Using 13C Solid-State NMR. Materials. 2013; 6(1):47-64.
Franco, Roberto W.A.; Brasil, Carlos A.; Mantovani, Gerson L.; Azevedo, Eduardo R.; Bonagamba, Tito J. 2013. "Molecular Dynamics of Poly(Ethylene Glycol) Intercalated in Clay, Studied Using 13C Solid-State NMR." Materials 6, no. 1: 47-64.