A novel route to polymeric sub-micron fibers and their use as templates for inorganic structures

Qian, Lei; Willneff, Elizabeth A.; Zhang, Haifei

doi:10.1039/b905130a

Cited by 47 publications

(46 citation statements)

References 30 publications

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“…94,95 Very recently, it was found that diluted aqueous polymer solutions could be frozen in liquid nitrogen and then freeze dried to produce polymeric nanofibres with diameters in the range of 200-600 nm. 96 A range of hydrophilic nanofibres including PVA, SCMC and alginate were successfully obtained. The polymeric nanofibres could then be used as templates to prepare hollow crystalline titania microtubes and Fe 2 O 3 nanofibres.…”

Section: Microwires and Nanowiresmentioning

confidence: 99%

“…Figure 9 shows the SEM images of SCMC nanofibres and hollow TiO 2 microtubes. 96 Chitosan and chitosanbased fibres with diameter from 100-700 nm were also produced by freeze drying 0.1 wt% solutions. 97 This method overcame some disadvantages of the electrospinning methods such as the requirement for toxic organic solvents or highly concentrated acetic acid as the solvent.…”

Section: Microwires and Nanowiresmentioning

confidence: 99%

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Controlled freezing and freeze drying: a versatile route for porous and micro-/nano-structured materials

Qian

Zhang

2010

J. Chem. Technol. Biotechnol.

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Freeze drying is a process whereby solutions are frozen in a cold bath and then the frozen solvents are removed via sublimation under vacuum, leading to formation of porous structures. Pore size, pore volume and pore morphology are dependent on variables such as freeze temperature, solution concentration, nature of solvent and solute, and the control of the freeze direction. Aqueous solutions, organic solutions, colloidal suspensions, and supercritical CO 2 solutions have been investigated to produce a wide range of porous and particulate structures. Emulsions have recently been employed in the freeze drying process, which can exert a systematic control on pore morphology and pore volume and can also lead to the preparation of organic micro-and nano-particles. Spray freezing and directional freezing have been developed to form porous particles and aligned porous materials. This review describes the principles, latest progress and applications of materials prepared by controlled freezing and freeze drying. First of all the basics of freeze drying and the theory of freezing are discussed. Then the materials fabricated by controlled freezing and freeze drying are reviewed based on their morphologies: porous structures, microwires and nanowires, and microparticles and nanoparticles. The review concludes with new developments in this area and a brief look into the future.

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Section: Microwires and Nanowiresmentioning

confidence: 99%

Section: Microwires and Nanowiresmentioning

confidence: 99%

Controlled freezing and freeze drying: a versatile route for porous and micro-/nano-structured materials

Qian

Zhang

2010

J. Chem. Technol. Biotechnol.

Self Cite

425

282

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“…Recently, sub-micron polymer fibres and inorganic structures were prepared by freeze drying dilute aqueous polymer solutions (Qian et al 2009). The fibres could be used as scaffolds with a high surface area and easy accessibility for a range of applications.…”

Section: (C) Silica Spheres On Sub-micron Fibresmentioning

confidence: 99%

“…The SCMC fibres were cross-linked with FeCl 3 before use (Qian et al 2009). Chitosan and Fe-SCMC composite fibres were added into the reaction system instead of polyHIPE beads as described above.…”

Section: (C) Stöber Synthesis In the Presence Of Nanofibresmentioning

confidence: 99%

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Porous silica spheres in macroporous structures and on nanofibres

Ahmed

Clowes

Willneff

et al. 2010

Phil. Trans. R. Soc. A.

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Porous nanospheres have a wide range of applications such as in catalysis, separation and controlled delivery. Among these nanospheres, syntheses and applications of porous silica nanospheres have been investigated extensively. Uniform porous silica nanospheres can be synthesized using a modified Stöber method. In the present study, porous silica spheres were prepared in the pre-formed emulsion-templated porous polyacrylamide (PAM). A hierarchical hybrid structure of mesoporous silica spheres was formed in the highly interconnected macroporous polymer. The polymer scaffold could be removed by calcination with porous silica spheres and the macroporous structures retained. This resulted from the close packing or aggregation of small silica nanospheres in the pores and on the surface of pores of PAM. The modified Stöber synthesis was further carried out in pre-formed polymer nanofibres (chitosan and sodium carboxymethyl cellulose). The structure of porous silica spheres on nanofibres was produced in the presence of the polymer or composite fibres. The corresponding inorganic structures were successfully obtained after calcination. The hierarchical structures of porous nanospheres within macroporous structures or on nanofibres are of potential interest to researchers in nanomaterials, porous polymers, supported catalysis and controlled delivery.

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Feature Synthesis of Hierarchically Porous Materials Based on Green Easy‐Leaching Concept

Chen

Yang

2011

Hierarchically Structured Porous Materials

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A novel route to polymeric sub-micron fibers and their use as templates for inorganic structures

Abstract: A simple and generic method is described to prepare polymeric sub-micron fibers by freeze drying dilute polymer solutions; these polymeric fibers are then used as templates to fabricate inorganic structures via a sol-gel process or ion crosslinking reaction.

Cited by 47 publications

References 30 publications

Controlled freezing and freeze drying: a versatile route for porous and micro-/nano-structured materials

Controlled freezing and freeze drying: a versatile route for porous and micro-/nano-structured materials

Porous silica spheres in macroporous structures and on nanofibres

Feature Synthesis of Hierarchically Porous Materials Based on Green Easy‐Leaching Concept

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