Crystalline macromolecules form folded-chain lamellar and metastable crystals. Annealing at a temperature below melting point results in a thickening of the metastable crystals to construct more stable ones. Such a process was visualized by AFM equipped with a hot stage in monolayers of poly(ethylene oxide) lamellar crystals on a silicon wafer surface. Our observations show that the monolayers can be thickened in a stepwise manner during stepwise heating to temperatures below the melting point. Our analyses show the thickening process and mechanism as follows:  At the first step a small portion of the lamellar crystals have the capability to be spontaneously thickened into a thicker one at a certain temperature range, giving rise to a difference in lamellar thickness. In the following step the thinner lamellae are forced to melt, and then the melted molecules enter an amorphous phase in which they are transported toward the thicker lamellae and finally recrystallize in the thicker ones. This inductive mechanism is analogous to the evaporation−condensation mechanism.

The detailed T(c)-sensitive crystal pattern transition from dendrites through fourfold-symmetric structures to faceted crystals of ultrathin poly(ethylene oxide) films has been experimentally observed using atomic force microscopy. The transition has been quantitatively described by the T(c)-dependences of the fractal dimension and of the velocity ratio caused by forward and transverse growths in crystal tips. The essential aspect of the pattern selection and transition is mainly the competition of two macroscopic mechanisms: Nucleation-limited and diffusion-limited growths which create faceted and dendritic crystal patterns, respectively. Their combination is a facet growth within a diffusion field which will create a faceted dendrite.

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A series of single-layer crystal patterns were observed in ultrathin films of 10 poly(ethylene oxide) fractions of molecular weights ranging from 2.02k to 932.0k g/mol. Morphology transitions between these different crystal patterns were quantitatively identified, and a morphology diagram with respect to supercooling and molecular weight dependencies was constructed. This will foster understanding of the macromolecular effects on the crystal pattern formation and selection critically associated with the parameters of molecular diffusion length and growth anisotropy.

Palladium-polypyrrole-foam nickel composite electrode (Pd/PPY(PTS)/Ni) was prepared through electrodeposited of palladium nanoparticles onto preformed electrodes (surface of electrodes was coated with potentiostatic electropolymerized polypyrrole). The stability of the fresh and used composite electrode was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). It was found that the surface state, morphology, and crystalline structure of the composite electrode were stable after 5 recycle uses. Electrocatalytic activity of the composite electrode was evaluated for the hydrodechlorination (ECH) of six kinds of dichlorophenols (DCPs). Results indicated that 2,4-DCP showed higher hydrodechlorination rate. Further, the pathway of electrochemical hydrodechlorination of six kinds of dichlorophenol isomers was investigated.