Polyvinyl Alcohol-Clay Complexes Formed by Direct Synthesis

Abstract

Synthetic hectorite clay minerals were hydrothermally crystallized with direct incorporation of a series of five water-soluble polyvinyl alcohols (PVA) of molecular weights from 9000-146,000. The molecular weight of PVA had little effect on the success of hydrothermal hectorite synthesis, d-spacing or the amount of polymer incorporated. The basal spacings range from 19.5 Å to 20.8 Å and the amount of polymer incorporated ranges from 20 wt.% to 23 wt.%. Incorporation of PVA within the clay inter-layers, along with Li(I) ions to compensate the lattice charge, is indicated. Thermal gravimetric analysis and small angle neutron scattering were used to further examine the polymer-clay systems. Small PVA-clay crystallites that are coated with excess PVA are indicated. Removal of the polymer does not alter the extended synthetic clay network, and the nitrogen BET surface area increases from 200 m²/g.