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The synergetic effects of water/ethanol mixed solvent and crystallization temperature upon CaCO3 polymorph discrimination and structural assembly under control of poly(sodium 4-styrenesulfonate) (PSS) were examined. CaCO3 mesocrystals of all three anhydrous polymorphs (calcite, aragonite, and vaterite) with progressively developed morphologies can be selectively realized in one system by consecutively decreasing the water/ethanol volume ratio (R) at the proper temperature. At a lower crystallization temperature (10 °C), decreasing the R value resulted in a polymorph transition of CaCO3 from pure calcite to pure vaterite, which was mainly attributed to the increased ethanol content and the resulting conformation change of PSS molecules. In contrast, CaCO3 polymorphs changed from pure calcite to almost pure aragonite at higher crystallization temperature (40 °C), where the temperature effect was more obvious and became the dominant parameter for CaCO3 polymorph selection. In addition, a dipole effect was em...

In this article, zein, a major protein of corn, has been used as biomimetic mineralization template to synthesize calcium phosphate by a bioinspired approach. A zein Langmuir monolayer, formed by self-assembling nanoglobules, is used to induce the mineralization of calcium phosphate at the air–liquid interface of the 10 times concentrated simulated body fluid. After biomimetic mineralization, zein films are covered with continuous minerals, grown from a small, curved morphology to straight, flake-like morphology, which are a mixture of dicalcium phosphate dehydrate and hydroxyapatite. With the continuous calcium phosphate incorporation, the modulus and hardness of mineralized zein films are enhanced to 11.6 and 0.32 GPa, higher than the values of pure zein films. The hybridization of inorganic minerals decreases the water contact angles from about 63° to 20°. The higher mechanical properties and hydrophilic properties could endow a friendly environment for fibroblast cells attachment, spread, and prolifer...

We report on the transformation of calcium carbonate microparticles (CCMs) to calcium phosphate microparticles (CPMs) with modulated morphologies and phases. In this additive-free transformation process, the use of templates or surfactants was circumvented, thereby eliminating potential contamination of the final products. The hydroxycarbonate apatite (HCAP) microspheres in high yield were more stable than CaCO3 microspheres in aqueous solution and had higher specific surface areas, which suggested that they had higher loading capability than their CaCO3 counterpart. In addition, the products had good biocompatibility because they were free from extraneous surfactants or stabilizers and, hence, did not require further purification. In order to examine the loading efficiency of these microspheres, carboxymethyl chitosan (CMC) and doxorubicin, which were both excellent biomedical materials, were taken as model high molecular weight and low molecular weight probes, respectively, to investigate the encapsulat...

In this article, we report that the phase transformation of magnesium amorphous calcium carbonate (Mg-ACC) can be easily realized in an ethanol/water mixed solution free from organic additives under mild conditions, and the phase transformation can be nicely captured by the choice of a suitable concentration of Mg-ACC, the volume ratio of ethanol to water as well as the reaction temperature. Moreover, a complex self-assembly process for the production of aragonite aggregate with ellipsoid shape in this binary solvent has been proposed. These results demonstrate that controlled phase transition from Mg-ACC can be easily achieved by using a binary reaction media. This study may provide some useful clues for understanding the mineralization process of CaCO3 in nature and implies that this method could be scaled up for industrial production of CaCO3 with different polymorphs.

Crystallization behavior of calcium carbonate (CaCO3) in water/ethanol mixed solutions under ambient conditions using polystyrene sulfonate (PSS) as a crystal growth modifier has been systematically investigated. The results have demonstrated that a switch from thermodynamic control to kinetic control in the crystallization process of CaCO3 can be easily realized by adding ethanol, which can have a significant influence on the polymorphs and morphologies of CaCO3 crystals. Calcite mesocrystals and vaterite complex aggregates with increasingly developed shapes can be obtained with an increase of the ethanol content in the solution. The polymorph change of CaCO3 crystals from pure calcite to a calcite dominated mixture and finally to a vaterite dominated mixture has also been nicely captured. Both CaCO3 crystals with different evolving phases and the polymorph change of CaCO3 from calcite to vaterite can be attributed to the balance between thermodynamic control and kinetic control in this special crystalli...

Novel anatase TiO2 hollow boxes and tree-like structures assembled by hollow tubes with a surface area as high as 241.89 m2/g can be synthesized in large scale by a simple hydrothermal method. A di...

Controlled growth of calcium carbonate crystals with complex forms was achieved using dextran as a crystal growth modifier beneath a dipalmitoylphosphatidylcholine (DPPC) monolayer, and calcite-core-calcium bilirubinate (CaBR)-side multiple crystals were also observed owing to the epitaxial growth of CaBR crystals on calcite. During the process, interactions between the DPPC monolayer and calcium ions were studied based on the analysis of the surface pressure−molecular area isotherms. Control over the crystallization of calcite with novel morphologies, such as octahedral crystals and round calcite disks, has been observed. Remarkable morphological changes and continuous structural evolution of calcite from rhombohedral crystal to octahedral crystal to uniform round disks and polyhedrons as concentrations of dextran increased have been observed. Moreover, semirigid multiplex templates consisting of calcium carbonate crystals and DPPC monolayers were established under physiological pH conditions, and epitax...

Using N,N′-dicyclohexylcarbodiimide (DCC) and l-serine as biologic additives, rutile TiO2 hollow spheres assembled by nanorods can be synthesized by a simple hydrothermal reaction route. A distinctive crystallization and transformation route of the rutile TiO2 hollow spheres has been proposed, which includes emergence of polycrystalline, mesoscale transformation to mesocrystals with morphologies of sectors, transformation of mesocrystals to bundles of rods based on oriented attachment, the simultaneous assembled process of sectors to solid spheres, and a cavitating process of solid spheres through the Ostwald ripening mechanism. Two ways of oriented attachment, side-by-side and end-to-end, were observed during the assembly process. It has been found that the presence of DCC and l-serine and their synergistic effects are essential for the formation of rutile TiO2 hollow spheres. The stability of the rutile TiO2 mesocrystals has been studied. The results have demonstrated that the mesocrystals could be main...

Shape-controlled synthesis of CoCO3 crystals has been achieved by a hydrothermal process in a mixed solvent of water and ethanol (or glycerol). Uniform CoCO3 crystals with novel structures can be fabricated by tuning the volume ratio of water and ethanol (or glycerol). The results demonstrated that the as-prepared CoCO3 crystal can act as an efficient precursor for production of nanoporous Co3O4 particles with pore sizes of 2.5 and 60 nm by calcination at 500 °C. The nanoporous Co3O4 particles show sensitive response and reversibility in sensing performance.

National Science Foundation of China (NSFC) [50732006, 20621061, 20671085, 2005CB623601]; Anhui Development Fund for Talent Personnel and Anhui Education Committee [2006Z027, ZD2007004-1]; Scientific Research Foundation for the Returned Overseas Chinese S

Single-crystalline trigonal tellurium (t-Te) nanotubes with sloping cross-section and hexagonal cross-section can be selectively synthesized on a large scale by a simple solvothermal reduction route, using tellurium dioxide (TeO 2) as tellurium source and ethylene glycol (EG) as both a reducing agent and a solvent in the presence of cetyltrimethyl ammonium bromide (CTAB) and cellulose acetate (CA), respectively. The individual Te nanotubes with cylindrical morphology and open ends have outer diameters of 100–500 nm, wall thicknesses of 50–100 nm, and lengths of 150–200 µm. Both kinds of Te nanotubes grow along the [001] direction and have excellent crystallinity. The optical properties and the stability in ethanol of the t-Te nanotubes with sloping cross section have been investigated.

Complex porous fluorescein microspheres with hierarchical superstructures and relievo-like complex fluorescein crystals can be easily generated by a recrystallization/reprecipitation method using poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) as structure directing agents at room temperature. The polymer-induced liquid precursor (PILP) phase is believed to play a role in the formation of such unusual shapes and structures. The shape and sizes of fluorescein crystals can be well controlled by adjusting the amounts of raw fluorescein precursor and polyelectrolytes. Furthermore, shaking and ultrasonic treatments can provide additional parameters for fabricated of fluorescein crystals with unique superstructures. The UV–vis spectroscopy indicates that the addition of PAH results in shifting of the absorption peak of monomer from 481 nm toward 494 nm, and such shifting is dependent on the PAH concentration.

Mineralization and crystallization of barium carbonate mesocrystals with various shapes and complex form using double hydrophilic block copolymers (DHBCs) as crystal growth modifiers in a mixed solvent composed of N,N-dimethylformamide (DMF) and deionized water (DIW) have been systematically investigated. The effects of polymer concentration, solvent, and the volume ratio of a mixed solvent on the controlled crystallization of BaCO3 mesocrystals have been examined. Shuttle-like BaCO3 rods with different sizes and ratios of average length (L) to maximum diameter (D) can be obtained by simply altering polymer concentration in the mixed solvent. In addition, complex hierarchical shuttle-like aggregated structures can be formed at the air/solution interface that were dramatically different from the structure obtained in bulk solution. This crystallization method in a mixed solvent containing a crystal growth modifier represents a simple but versatile route to achieve unique synergic effects on manipulation of...

Single-crystal PbSO4 (anglesite) nanorods with different diameter and aspect ratios have been synthesized by a microemulsion technique in a SDS/hexane/hexanol/water microemulsion. The effect of con...

Zinc oxide flowers composed of either branched spindles or prismatic whiskers with flat ends have been synthesized by hydrothermal treatment of Zn3(OH)2V2O7·H2O nanosheets in sodium hydroxide aqueous solution at 120 °C. The influence of basicity, temperature, and reaction time on the formation of such structures was investigated. The room-temperature photoluminescence spectrum of the ZnO branched structures shows strong green-yellow emission. The results indicated that the choice of a precursor with special shape could have significant influence on the growth of ZnO crystals. This precursor could be used for the synthesis of other zinc compounds with complex morphology and special nanostructures.

Monoclinic and orthorhombic PbCrO4, Pb2CrO5, and K2Pb(CrO4)2 nanocrystallites with different shapes can be selectively synthesized by a room temperature solution reaction without adding any additives. The results demonstrated that the manipulation of pH value and the molar ratio of Pb(Ac)2 and K2CrO4 can effectively affect the formation of polymorphs and phases. This facile room temperature approach provides a useful route for the selective synthesis of lead chromate pigments with different phases and polymorphs, a method which could be extended for other inorganic systems.

Complex BaCO3 superstructures can be easily generated by using poly(sodium 4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) as structure directing agents in the mineralization pro...