Electron microscope observations on microgel and linear macromolecules of polyacrylonitrile

The presence of microgel particles, which were expected on the basis of other indirect measurements to occur in polyacrylonitrile solutions, is directly demonstrated in these solutions with the electron microscope. The particles are spherical in shape and have a uniform size of about 500 A. These microgel particles are probably crosslinked or branched giant molecules. On the side of these particles linear molecular threads are observed. Their bundling together into microfibrils is also observed.