Poly (Vinyl Alcohol)/ Montmorillonite Hybrid Materials Preparated by “In Situ” Polymerization

MARÍA CELESTE CARRERA; MARCOS LOPES DIAS; VICTOR PITA; ELEONORA ERDMANN; DELICIA ACOSTA; HUGO DESTÉFANIS

Castellaneta Marina, Italia

Conferencia; XIV International Clay Conference; 2009

Micro Et Nano Scientiae Mare Magnum

The hybrid materials consisting of inorganic nanolayers of montmorillonite (MMT) clay and organic polymers have been an emerging method to improve properties of poly(vinyl alcohol) (PVA) and many PVA-based nanocomposites have recently been developed for different applications. A series of polymer–clay hybrid materials of PVA/sodium and ammonium montmorillonite clays was prepared by “in situ” polymerization. First the sodium and ammonium montmorillonite were pretreated in two different ways one of them with vinylacetate monomer during 24 h at room temperature and the other with vinylacetate/ propanol solution during 24 h at room temperature. The polymerization was carried out using benzoyl peroxide as initiator under N2 atmosphere  and followed by alcoholisis  with KOH/methanol solutions. Ratios of clay/ PVA varying  5, 10 and 20  % (w/w)  were used.  The hybrid materials  were characterized using IR spectroscopy, X-Ray diffraction, thermogravimetric analysis (TG, DTGA), DSC techniques. The average MW of the PVA was determined by GPC resulting a Mw 20672 and a polydispersity index (PDI) of  2.47. The IR spectra show the characteristic peaks of clay minerals. The montmorillonite shows characteristic clay mineral peaks, similar spectrum was revealed by the modified montmorillonite, but in this case, the organic matter peaks are sharper than those of the montmorillonite without treatment. XRD patterns before polymerization show shifting of (001) peak to lower angle when clay was pretreated with vinylacetate/ propanol solution. DSC analysis of PVA/MMT hybrid materials show an important Tg improvement respect to PVA. In the same way TGA thermograms show better thermal stability.