Search

Multilayer ultrathin films composed of nitro-containing diazoresin (NDR) as polycation and poly(amidoamine) dendrimers with carboxyl terminal groups (PAMAMC) (G = 1.5, 2.5, 3.5, and 4.5) as polyanion were fabricated on mica by electrostatic layer-by-layer deposition. Subsequent UV irradiation converted the interlayer linkage from ionic to covalent. The films were characterized with UV−vis, FTIR, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and X-ray diffraction (XRD). The results show that the uniform multilayer films were formed. All the films with dendrimers of various generations as building blocks have a very smooth surface with a mean roughness of about 0.8−1.1 nm. The thickness of the PAMAMC−NDR bilayer in the films increases with the generation number of the dendrimer, but the average thickness of the dendrimer monolayer is smaller than the diameter of the ideal spherical model of dendrimers with an extended conformation of all branches. They are significantly compressed i...

Additive-free high-energy faces of CaCO3 in the calcite modification were synthesized and found to reconstruct fast into the stable (104) faces in solution within 2 h, which is not observed in the bad solvent ethanol. (104) faces can be detected by single molecule force spectroscopy. A novel embedding process of calcite crystals with defined exposed surfaces generated on a self-assembled surfactant monolayer into a silica monolith is described as well as the time-resolved analysis of the reconstruction of unstabilized high-energy surfaces, which is faster than assumed from the equilibrium Wulff rule.

Hybrid nanoparticles of carboxyl-terminated generation 4.5 (G4.5) poly(amidoamine) dendrimers with platinum nanocrystals encapsulated inside them were prepared in water. The obtained nanoparticles were treated by size-selective precipitation to refine the size distribution. On a carbon-coated copper grid, the nanoparticles formed a monolayer film when observed by TEM. The sizes of the hybrid nanoparticles were evenly dispersed, with an average diameter of 4.0 nm. The Fourier transform power spectrum proved that the monolayer film had short-range order, and locally hexagonal packing was present. High-resolution transmission electron microscopy showed that the encapsulated Pt atoms were gradually rearranged as metal nanocrystals after a period of time.