A Synthetic Analogue of the Biomineralization Process:  Formation of Novel Lead Sulfide Phases

Abstract

A biomimetic in-situ synthesis of PbS in PEO has been devised, which produces composites in which the inorganic phase can display regularity of morphology and crystallographic orientation. This in-situ synthesis of PbS in a PEO film has also produced two previously unknown phases of lead sulfide, one of which can be described as "compressed" galena (PbS), the other is a new form of lead disulfide (PbS 2 ).

Fabrication of PbS microstructures with different shapes in aqueous solutions of amphiphilic triblock copolymer

“…The above results indicate that the size of F127 micelles is significantly increased after the addition of Pb(Ac) 2 . The resulting large spherical aggregates could be ascribed to the complexation of Pb 2+ with the EO units, as confirmed by the fact that the EO units of poly (ethylene oxide) (PEO, M w ¼ 200.000) can form hydrogen bond with Pb 2+ in a PEO film [34,35]. It is noted that the presence of Pb(Ac) 2 is unnecessary for the formation of micelles, and the TEM image of complex F127 micelles with Pb 2+ is only used to characterize the formation process.…”

“…The chain conformation of block copolymer monomers can be adjusted by changing the experimental conditions, such as the block copolymer concentration, reaction temperature, which may provide rich structure-directing matrixes for the shape control of functional materials. Furthermore, the metal ions with low degree of hydration, such as Pb 2+ , have less strong binding by EO units in comparison with those with high degree of hydration, such as Zn 2+ , and Cd 2+ [34,35], it is therefore difficult to form various sulfide microstructures by block copolymer micelles with relatively short EO chains. On these grounds, we proposed a controlled synthesis of PbS in F127 solutions.…”

Formation of Metastable Vaterite Crystals in a Polymer Matrix by Gaseous Diffusion

“…There are reports where crystallizing an inorganic phase inside a polymer has produced high-pressure phases of cadmium sulfide 19 , novel and high-pressure phases of lead sulfide 20 and in one instance the formation of crystalline lithium niobate without the application of heat 21 . It is suggested that "the density or rigidity of the matrix regulates the phase of the crystals that form, predominantly by a "solid state" densification effect, whereby the solid state of the polymer matrix acts to confine growth spatially such that the growing crystal is forced to adopt a more dense form than it would in solution growth, resulting in the formation of high-pressure phases" 22 .…”

Crystal growth of barium nitrate on thiol-terminated self-assembled monolayers and a Raman spectroscopic investigation of the crystal facets

“…Therefore, how the oriented growth of the crystals can be controlled has recently attracted much attention [1,2]. As a typical system of induced nucleation, biomineralization is currently being very actively studied because the materials made by biomineralization have highly unified and orderly crystal morphologies, sizes, and orientations [3,4]. Inspired by this natural phenomenon, the biomineralization method is widely used in the preparation of special crystals of inorganic or organic/inorganic composite materials.…”