Interfacial regulation of crystallization in aqueous environments

Regulation of the Deposition Morphology of Inkjet-Printed Crystalline Materials via Polydopamine Functional Coatings for Highly Uniform and Electrically Conductive Patterns

We report a method to achieve highly uniform inkjet-printed silver nitrate (AgNO3) and a reactive silver precursor patterns on rigid and flexible substrates functionalized with polydopamine (PDA) coatings. The printed AgNO3 patterns on PDA-coated substrates (glass and polyethylene terephthalate (PET)) exhibit a narrow thickness distribution ranging between 0.9 and 1 μm in the line transverse direction and uniform deposition profiles in the line axial direction. The deposited reactive silver precursor patterns on PDA-functionalized substrates also show "dome-shaped" morphology without "edge-thickened" structure due to "coffee-stain" effect. We posit that the highly uniform functional ink deposits formed on PDA-coated substrates are attributable to the strong binding interaction between the abundant catecholamine moieties at the PDA surface and the metallic silver cations (Ag(+) or Ag(NH3)(2+)) in the solutal inks. During printing of the ink rivulet and solvent evaporation, the substrate-liquid ink (S-L) interface is enriched with the silver-based cations and a solidification at the S/L interface is induced. The preferential solidification initiated at the S-L interface is further verified by the in situ visualization of the dynamic solidification process during solvent evaporation, and results suggest an enhanced crystal nucleation and growth localized at the S-L interface on PDA functionalized substrates. This interfacial interaction mediates solute transport in the liquid phase, resulting in the controlled enrichment of solute at the S-L interface and mitigated solute precipitation in both the contact line region and the liquid ink-vapor (L-V) interface due to evaporation. This mediated transport contributes to the final uniform solid deposition for both types of ink systems. This technique provides a complementary strategy for achieving highly uniform inkjet-printed crystalline structures, and can serve as an innovative foundation for high-precision additive delivery of functional materials.

Influence of sodium dodecyl sulfate and static magnetic field on the properties of freshly precipitated calcium carbonate

Properties of calcium carbonate precipitated from aqueous solutions of CaCl(2) and Na(2)CO(3) in the presence of sodium dodecyl sulfate (SDS) and S-S 0.1 T magnetic field (MF) were studied. The nucleation and precipitation processes of CaCO(3) were investigated by pH and zeta potential measurements at 20 +/- 1 degrees C up to 2 h after mixing the solutions. Also the amounts of calcium carbonate deposited on the glass surfaces and its structure were examined. It was found that SDS influences the kinetics of precipitation, crystallographic forms, and crystal size of CaCO(3). The SDS effects are more pronounced in MF presence. A small amount of SDS accelerates transformation of vaterite into calcite, whereas increasing surfactant concentration moderates such a transformation. On the other hand, in all the systems, MF in the presence of SDS causes a slower transformation of vaterite into calcite. These effects are reflected in pH and zeta potential changes, although there is no clear dependence between the SDS amount present during the precipitation and changes of the parameters investigated. It seems that MF effect is most significant at a defined optimal SDS concentration. The results, however, do not allow suggestion of any detailed mechanism of the field interaction.

In situ analysis of the organic framework in the prismatic layer of mollusc shell

A novel in situ analytic approach was constructed by means of ion sputtering, decalcification and deprotein techniques combining with scanning electron microscopy (SEM) and transmission electron microscope (TEM) ultrastructural analysis. The method was employed to determine the spatial distribution of the organic framework outside and the inner crystal and organic/inorganic interface spatial geometrical relationship in the prismatic layer of cristaris plicate (leach). The results show that there is a substructure of organic matrix in the intracrystalline region. The prismatic layer forms according to strict hierarchical configuration of regular pattern. Each unit of organic template of prismatic layer can uniquely determine the column crystal growth direction, spatial orientation and size. Cavity templates are responsible for supporting. limiting size and shape and determining the crystal growth spatial orientation, while the intracrystal organic matrix is responsible for providing nucleation point and inducing the nucleation process of calcite. The stereo hierarchical fabrication of prismatic layer was elucidated for the first time.

Self-assembled ceramics produced by complex-fluid templation

This review examines the use of self-assembly in the fabrication of ceramic mesostructures, emphasizing the use of amphiphilic surfactants and block copolymers. The association between this area of research and biomimetics is discussed, linking developments in synthetic self-assembly with biomineralization. The fabrication of hierarchical structures through the use of simultaneous processing is shown to be a necessary condition for applications of this new technology.