Melt intercalation of polystyrene in layered silicates

We have studied the melt intercalation of polystyrene into organically modified sodium bentonite, a layered, mica-type silicate, using a variety of techniques. Wide-angle X-ray scattering experiments on polymer/silicate hybrid samples demonstrate that intercalation of polymer chains leads to an ∼25% increase in the spacing between silicate layers. The magnitude of this increase, compared with the radius of gyration of the melt polymer, implies a flattened conformation of chains in the galleries. Low voltage scanning electron microscopy reveals voids in the intercalated hybrid matrix that correspond to regions where pristine polymer was present in the physical mixture of polymer and silicate before intercalation. Differential scanning calorimetry shows that only unintercalated polymer contributes to the measured glass transition trace, so that the magnitude of the trace is diminished upon intercalation.