This paper was presented at The 2009 Annual Meeting of The Chinese Society of Chemical Science and Technology in the UK (CSCST) & The Society of Chemical Industry—Chinese UK Section (SCI—CS).
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Review
Controlled freezing and freeze drying: a versatile route for porous and micro-/nano-structured materials†
Article first published online: 2 SEP 2010
DOI: 10.1002/jctb.2495
Copyright © 2010 Society of Chemical Industry
Issue
Journal of Chemical Technology and Biotechnology
Volume 86, Issue 2, pages 172–184, February 2011
Additional Information
How to Cite
Qian, L. and Zhang, H. (2011), Controlled freezing and freeze drying: a versatile route for porous and micro-/nano-structured materials. J. Chem. Technol. Biotechnol., 86: 172–184. doi: 10.1002/jctb.2495
- †
Publication History
- Issue published online: 10 JAN 2011
- Article first published online: 2 SEP 2010
- Manuscript Accepted: 23 JUL 2010
- Manuscript Revised: 15 JUL 2010
- Manuscript Received: 2 JUN 2010
Funded by
- EPSRC. Grant Number: EP/F016883/1
- Abstract
- Article
- References
- Cited By
Keywords:
- controlled freezing;
- porous materials;
- porous ceramics;
- aligned porous structures;
- microwires;
- nanofibres;
- organic nanoparticles;
- porous microparticles
Abstract
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 CO2 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. Copyright © 2010 Society of Chemical Industry