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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

Optical microscopic images of (a) CMC-COOH and (b) hollow silica microcoil prepared using CTAB.
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Figure 2: Optical microscopic images of (a) CMC-COOH and (b) hollow silica microcoil prepared using CTAB.

Mentions: As can be seen in Figure 1a,b, the CMC-COOHs used as templates are polydisperse in diameter, pitch and length; some of them are hundreds of micrometers in length. During the sol-gel reaction, the surface of the CMC-COOHs is covered by a silica deposit. After calcination, i.e. after removal of CMC-COOHs, silica coils are left (see Figure 1c). Some sections of the coils seem more transparent, due to their very thin silica walls, while coil size and morphology appear similar to that of original CMC-COOHs. Silica particles can also be observed on the surface of the coils. The differences in contrast of the two specimens (CMC-COOHs and silica coils) can also be clearly observed by the optical microscope (Figure 2). The images are a proof that the CMC-COOHs used as templates have been burnt off and silica coils are left over, although also non-CMC-templated silica particles are obtained mixed with the coils, as isolated silica particles can also form in the bulk solution during the sol-gel reaction. The amount of non-CMC-templated silica decreases by reducing the CTAB/CMC-COOH ratios, so that most of CTAB is adsorbed on the CMC-COOH surface.


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)

Optical microscopic images of (a) CMC-COOH and (b) hollow silica microcoil prepared using CTAB.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Optical microscopic images of (a) CMC-COOH and (b) hollow silica microcoil prepared using CTAB.
Mentions: As can be seen in Figure 1a,b, the CMC-COOHs used as templates are polydisperse in diameter, pitch and length; some of them are hundreds of micrometers in length. During the sol-gel reaction, the surface of the CMC-COOHs is covered by a silica deposit. After calcination, i.e. after removal of CMC-COOHs, silica coils are left (see Figure 1c). Some sections of the coils seem more transparent, due to their very thin silica walls, while coil size and morphology appear similar to that of original CMC-COOHs. Silica particles can also be observed on the surface of the coils. The differences in contrast of the two specimens (CMC-COOHs and silica coils) can also be clearly observed by the optical microscope (Figure 2). The images are a proof that the CMC-COOHs used as templates have been burnt off and silica coils are left over, although also non-CMC-templated silica particles are obtained mixed with the coils, as isolated silica particles can also form in the bulk solution during the sol-gel reaction. The amount of non-CMC-templated silica decreases by reducing the CTAB/CMC-COOH ratios, so that most of CTAB is adsorbed on the CMC-COOH surface.

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