Morphology of Amorphous Polymers

Our general concept of the amorphous morphology of polymers is that of a structureless mass of coiled and intercoiled molecules. However, replica studies of freeze-fractured rubbers, amorphous polystyrene and polymethyl methacrylate and ion-etched glassy polycarbonate often suggest the presence of nodular structures (100-1000 Å) of unknown origin. Recently a nodular ball-like structure of the order of 100 Å was also observed in thin films of amorphous polyethylene terephthalate, its appearance being due to polymer molecules tending to back fold and arranging themselves more or less parallel to one another. We have extended these studies to several other polymers including amorphous and crystallizable polystyrene and polymethyl metha-crylate, trans- and cis-polyisoprene, polyphenylene oxide, etc. and have observed similar ball-like structures (Figs. 1 and 2). The size of these structures may vary from polymer to polymer (30-100 Å), however for a given polymer no substantial size variation has been observed with respect to preparation conditions, e.g., temperature, solvent and molecular weight.