The surface properties were examined with a JOEL JSM-5410LV scanning electron microscope (SEM) (Tokyo, Japan). The films, in re-swollen form, were dehydrated in ascending grades of ethanol and dried in a Tousimis Samdri-780 critical point dryer (Maryland, USA) using liquid carbon dioxide as a transitional fluid. The dried films were sputtered with gold in a Balzers-SCD 040 sputter coater (Balzers, Liechtenstein). The accelerating voltage was adjusted to 15 kV. The specimens were examined at a magnification of 10,000×.