In-situ Polymerization vs direct Polymer Incorporation for the Nanocomposite PSS/LDH
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In-situ Polymerization vs direct Polymer Incorporation for the Nanocomposite PSS/LDH Fabrice Leroux, El Mostafa Moujahid, Joël Cellier and Jean-Pierre Besse Laboratoire des Matériaux Inorganiques, UMR 6002, Université Blaise Pascal, 63177 Aubière cédex. Email: [email protected]
ABSTRACT Interleaved polystyrene sulfonate polymer between a layered double hydroxide of composition Zn2Al(OH)6 Cl. nH2O are prepared either by direct exchange or by in-situ 13 polymerization of the monomer. The latter is confirmed by C CP-MAS solid state NMR spectroscopy. This technique provides also clear evidence of the strong interaction between the incorporated monomer and the LDH inorganic framework. A shielding of the aromatic carbon attached to the sulfonate group is observed, this is transmitted through the carbonaceous skeleton to the vinylic carbon. The 2D structure is stabilized with the presence of organic moieties, and even more through the in-situ polymerization process, as exemplified with the conversion from Oh to Td aluminium cations environment. However the difference is diminished with the heating process. The exfoliation/restacking process is found to be here unappropriate, giving rise to ill-defined materials.
INTRODUCTION Since a decade a lot of interest is focussed on the preparation of new nanocomposite materials and especially those built from the assembly of an inorganic 2D - host material and a polymer [1-2]. Owing to the highly tunable properties of its two constituents, these nanocomposites find their applications in a large number of fields such as those emphasizing the mechanical enhancement, gas permeability or polymer electrolyte [3-4]. Lately, a great interest has been devoted to the preparation of new nanocomposites enhancing the thermal stability, especially the polymer / clay systems [5]. In this study, a layered double hydroxide (LDH) material of composition Zn2Al(OH)6Cl. 2H2O is designed as the inorganic host framework. Lamellar LDH structure is commonly described as edge-sharing octahedra sheets in which by comparison to the brucite M(OH)2 a part of divalent cations is replaced by trivalent cations. The excess of 3+ charge, i.e. Al content, is counterbalanced by interlayered anions, leading to an anionic exchange capacity (A.E.C) as high as 3.07 meq per g and to a layer charge of 25.4 Å2/e- in the case of Zn2Al(OH)6Cl. 2H2O [6]. It is known that the mutual organisation of a nanocomposite is highly dependent of the assembly of its components. The incorporation of polymer between the galleries may proceed via different soft-chemistry routes such as coprecipitation, in-situ polymerization, direct exchange, reconstruction or restacking [7]. In-situ polymerization process is compared to direct exchange method in term of Q2.2.1 Downloaded from https://www.cambridge.org/core. Access paid by the UCSB Libraries, on 08 Sep 2017 at 16:09:33, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/PROC-726-Q2.2
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