Direct observation of growth of lamellae and spherulites of a semicrystalline polymer by AFM

The dynamic growth processes of lamellae and spherulites of a polymer (BA-C 8) synthesized by condensation polymerization of bisphenol A and 1,8-dibrom ooctane were directly observed using an atomic force microscope at 25 +/- 1 degreesC. The phase shift measured at the tip of growing lamellae is lower than the phase shifts of the other regions of the lamellae. This result in dicates that the growth front of a lamella is softer and contains more defe cts than the developed ones. The growth process of lamellae and the formati on of spherulites were studied. A lamella was observed to breed more lamell ae by inducing adjacent secondary nuclei and to develop into a lamellar she af and finally into a spherulite. The lamellae were preferentially oriented edge-on with respect to the surface of the BA-C8 polymer thin films. The d etailed observations on the formation of the secondary nuclei indicated tha t the branching of the lamellae was only a temporary growth stage of the se condary lamellae. At the branch point, the secondary lamellae could propaga te in both backward and forward directions with respect to the growth direc tion of the parent lamellae.