Synthesis of poly(vinyl benzal) from poly(vinyl alcohol) in nonaqueous medium

✍ Scribed by P. Chetri; N. N. Dass

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 377 KB
• Volume: 62
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19961219)62:12<2139::aid-app16>3.0.co;2-0

✦ Synopsis

Poly(viny1 alcohol) (PVA) is soluble only in water and so some important derivatives like esters cannot be prepared from PVA. The 100% conversion of PVA to acetal is also elusive as there is strong intermolecular and intramolecular hydrogen bonding. However, PVA can be dissolved in a nonaqueous medium in the presence of a small amount of C2H5N03 -DMSO(EN -DMSO) and so a maximum extent of conversion may be possible.

Here, we report the preparation of poly(viny1 benzal) (PVB) by acid-catalyzed homogeneous acetalization of PVA with benzaldehyde in a nonaqueous medium. The formation of PVB was confirmed by IR and 'H-NMR spectra. The molecular mass of the polymer was determined by the GPC method. The PVB prepared had a degree of acetalization of 95 mol %. The glass transition temperature, Tg, was measured from differential scanning calorimetric (DSC) thermograms. Thermal stabilities were checked by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG). A possible mechanism of three-step thermal decomposition of PVB is proposed.