The Formation of Curved Polymer Crystals: Polychlorotrifluoroethylene.

The habits and fine structure of crystals of polychlorotrifluoroethylene (PCTFE) grown from dilute solution were studied as functions of crystallization temperature. The solvent used was a low molecular weight PCTFE oil. The simplest crystals found were monolayered chain folded lamellae formed at 110 °C. These lamellae are planar and possess an unusual texture characterized by the presence of fine channel-like voids in the interior of the crystals. These lamellae do not exhibit well-formed crystal faces but are disc-like in overall shape. At lower crystallization temperatures the crystals take the form of complex arrays of curved lamellae which are aggregated into, among others, watchglass-shaped or hollow spherical objects. The variation of the curvature of the crystals with crystallization temperature is discussed in the light of previous studies of the formation of curved crystals of poly(4-methylpentene-1) and polyoxymethylene.