Limits...
A combination of hard and soft templating for the fabrication of silica hollow microcoils with nanostructured walls.

Rodriguez-Abreu C, Vilanova N, Solans C, Ujihara M, Imae T, López-Quintela A, Motojima S - Nanoscale Res Lett (2011)

Bottom Line: Moreover, they have mesoporous walls (pore size ≈ 3 nm) with some domains where pores are ordered in a hexagonal array, originated from surfactant micelles.The obtained silica microcoils also show preferential adsorption of cationic fluorescent dyes.A mechanism for the formation of silica microcoils is proposed.

View Article: PubMed Central - HTML - PubMed

Affiliation: International Iberian Nanotechnology Laboratory (INL), Av, Mestre José Veiga, Braga, 4715-310, Portugal. crodriguez@inl.int.

ABSTRACT
Hollow silica microcoils have been prepared by using functionalized carbon microcoils as hard templates and surfactant or amphiphilic dye aggregates as soft templates. The obtained materials have been characterized by electron and optical microscopy, nitrogen sorption and small angle X-ray scattering. The obtained hollow microcoils resemble the original hard templates in shape and size. Moreover, they have mesoporous walls (pore size ≈ 3 nm) with some domains where pores are ordered in a hexagonal array, originated from surfactant micelles. The obtained silica microcoils also show preferential adsorption of cationic fluorescent dyes. A mechanism for the formation of silica microcoils is proposed.

No MeSH data available.


Related in: MedlinePlus

Proposed scheme for the mechanism of formation of hollow silica microcoils.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211418&req=5

Figure 6: Proposed scheme for the mechanism of formation of hollow silica microcoils.

Mentions: Based upon the experimental evidence, a mechanism for the formation of silica hollow microcoils with mesoporous walls can be proposed (see Figure 6). Cationic aggregates, which are expected to be elongated at the used concentrations of amphiphile and electrolyte [17,21,22], adsorb on the surface of negatively-charged CMC-COOHs. When TEOS is added at high pH, the silica coating is built up through anchoring of silica via electrostatic interaction of siloxy ions with ammonium ions of the amphiphilic molecules adsorbed on CMCs. During the sol-gel reaction, free cationic aggregates are also cooperatively incorporated as porogens in the polysiloxane gel. At this stage, there might be some preferential orientation of aggregates in the silica layers. Depending on amphiphile concentration, excess silica particles with inner mesostructure forms in the bulk solution and some of those particles also adhere to the silica layers on the surface of CMCs. Finally, upon calcination, the CMCs (hard templates) and amphiphilic molecules (soft templates) are burnt off, and silica hollow microcoils with porous walls are obtained.


A combination of hard and soft templating for the fabrication of silica hollow microcoils with nanostructured walls.

Rodriguez-Abreu C, Vilanova N, Solans C, Ujihara M, Imae T, López-Quintela A, Motojima S - Nanoscale Res Lett (2011)

Proposed scheme for the mechanism of formation of hollow silica microcoils.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211418&req=5

Figure 6: Proposed scheme for the mechanism of formation of hollow silica microcoils.
Mentions: Based upon the experimental evidence, a mechanism for the formation of silica hollow microcoils with mesoporous walls can be proposed (see Figure 6). Cationic aggregates, which are expected to be elongated at the used concentrations of amphiphile and electrolyte [17,21,22], adsorb on the surface of negatively-charged CMC-COOHs. When TEOS is added at high pH, the silica coating is built up through anchoring of silica via electrostatic interaction of siloxy ions with ammonium ions of the amphiphilic molecules adsorbed on CMCs. During the sol-gel reaction, free cationic aggregates are also cooperatively incorporated as porogens in the polysiloxane gel. At this stage, there might be some preferential orientation of aggregates in the silica layers. Depending on amphiphile concentration, excess silica particles with inner mesostructure forms in the bulk solution and some of those particles also adhere to the silica layers on the surface of CMCs. Finally, upon calcination, the CMCs (hard templates) and amphiphilic molecules (soft templates) are burnt off, and silica hollow microcoils with porous walls are obtained.

Bottom Line: Moreover, they have mesoporous walls (pore size ≈ 3 nm) with some domains where pores are ordered in a hexagonal array, originated from surfactant micelles.The obtained silica microcoils also show preferential adsorption of cationic fluorescent dyes.A mechanism for the formation of silica microcoils is proposed.

View Article: PubMed Central - HTML - PubMed

Affiliation: International Iberian Nanotechnology Laboratory (INL), Av, Mestre José Veiga, Braga, 4715-310, Portugal. crodriguez@inl.int.

ABSTRACT
Hollow silica microcoils have been prepared by using functionalized carbon microcoils as hard templates and surfactant or amphiphilic dye aggregates as soft templates. The obtained materials have been characterized by electron and optical microscopy, nitrogen sorption and small angle X-ray scattering. The obtained hollow microcoils resemble the original hard templates in shape and size. Moreover, they have mesoporous walls (pore size ≈ 3 nm) with some domains where pores are ordered in a hexagonal array, originated from surfactant micelles. The obtained silica microcoils also show preferential adsorption of cationic fluorescent dyes. A mechanism for the formation of silica microcoils is proposed.

No MeSH data available.


Related in: MedlinePlus